Unmanned Aircraft Systems: Roles, Missions, and Future Concepts
Congressional research reportJul 18, 2022
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Unmanned Aircraft Systems: Roles, Missions,
and Future Concepts
July 18, 2022
Congressional Research Service
https://crsreports.congress.gov
R47188
SUMMARY
Unmanned Aircraft Systems: Roles, Missions,
and Future Concepts
Unmanned aircraft systems (UAS) have gained increased prominence in U.S. military operations.
The Department of Defense (DOD) is currently developing advanced UAS, along with optionally
crewed aircraft, as part of its modernization strategy. The roles and missions of UAS are relevant
to Congress in authorizing, appropriating, and providing oversight to DOD and the military
services for these systems.
Over the past decades, military forces have used UAS to perform various tasks, including
intelligence, surveillance, and reconnaissance;
close air support;
cargo and resupply; and
communications relay.
R47188
July 18, 2022
John R. Hoehn,
Coordinator
Analyst in Military
Capabilities and Programs
Kelley M. Sayler
Analyst in Advanced
Technology and Global
Security
Michael E. DeVine
Analyst in Intelligence and
National Security
Analysts and DOD argue that UAS could replace crewed aircraft for a number of missions,
including
aerial refueling;
air-to-air combat;
strategic bombing;
battle management and command and control (BMC2);
suppression and destruction of enemy air defenses; and
electronic warfare (EW).
In addition, DOD is developing several experimental concepts—such as aircraft system-of-systems, swarming, and lethal
autonomous weapons—that explore new ways of employing future generations of UAS.
In evaluating appropriations and authorizations for potentially new and future UAS programs, missions, and concepts,
Congress may consider the following issues:
the proliferation of UAS able to function as lethal autonomous weapons and its implications for global
arms control;
costs of future UAS compared with crewed aircraft;
personnel and skills implications of UAS;
concepts of operation and employment; and
the proliferation of uncrewed aircraft technologies.
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Unmanned Aircraft Systems: Roles, Missions, and Future Concepts
Contents
Background ..................................................................................................................................... 1
Current Roles of UAS ............................................................................................................... 1
Intelligence, Surveillance, and Reconnaissance (ISR) ........................................................ 1
Close Air Support (CAS) .................................................................................................... 3
Communications Relay ....................................................................................................... 4
Potential Roles and Missions for UAS ...................................................................................... 5
Aerial Refueling .................................................................................................................. 5
Air-to-Air Combat .............................................................................................................. 6
Combat Search and Rescue/Casualty Evacuation ............................................................... 6
Cargo and Resupply ............................................................................................................ 7
Strategic Bombing .............................................................................................................. 8
Battle Management Command and Control (BMC2) ......................................................... 9
Suppression and Destruction of Enemy Air Defenses ........................................................ 9
Electronic Warfare ............................................................................................................ 10
Advantages and Disadvantages of Unmanned Aircraft Systems ............................................. 11
Aircraft Performance ......................................................................................................... 11
Risk Tolerances ................................................................................................................. 12
Communications Requirements ........................................................................................ 13
Experimental Concepts.................................................................................................................. 13
Aircraft System-of-Systems .................................................................................................... 14
AI-Enabled Manned-Unmanned Teaming .............................................................................. 14
Mission Support ................................................................................................................ 14
Autonomous Dogfighting ................................................................................................. 16
Swarming ................................................................................................................................ 17
Lethal Autonomous Weapon Systems ..................................................................................... 18
Potential Issues for Congress......................................................................................................... 19
Lethal Autonomous Weapons .................................................................................................. 19
Cost of Future UAS Compared with Crewed Systems ........................................................... 21
Personnel Implications ............................................................................................................ 22
Proliferation of Uncrewed Technologies ................................................................................. 23
Figures
Figure 1. RQ-4 Global Hawk UAS Landing in Guam .................................................................... 3
Figure 2. Air Force MQ-1 Predator Armed with a Hellfire Missile ................................................ 4
Figure 3. EQ-4 ................................................................................................................................. 5
Figure 4. Volansi VOLY C10........................................................................................................... 8
Figure 5. ADM-160A Miniature Air-Launched Decoy (MALD) ................................................... 11
Figure 6. Valkyrie UAS Deploys ALTIUS-600 Small UAS .......................................................... 16
Figure 7. Gremlin UAS Swarm ..................................................................................................... 18
Appendixes
Appendix. Intelligence Support of UAS Targeting in Counterterrorism Operations .................... 25
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Unmanned Aircraft Systems: Roles, Missions, and Future Concepts
Contacts
Author Information........................................................................................................................ 27
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Unmanned Aircraft Systems: Roles, Missions, and Future Concepts
Background1
The United States has a number of unmanned aircraft systems (UAS) operating across the
military services.2 These aircraft have demonstrated their ability to perform many types of
missions and may perform more complex missions in the future. Congress will likely debate and
decide whether and how to allocate funds for military UAS in its yearly appropriations and
authorization activity, as well evaluate them more broadly in its oversight role.
The U.S. military typically refers to remotely piloted vehicles (RPVs) as unmanned aircraft
vehicles (UAVs). UAVs are either a single air vehicle (with associated surveillance sensors) or a
UAV system, which typically consists of an air vehicle paired with a ground control station
(where the pilot actually sits) and support equipment.3 With the FY2023 President’s budget, the
Air Force has begun to use the term “uncrewed” to describe remotely piloted or unmanned
aircraft systems.4 The Air Force made this distinction defining all aircraft flying without an
aircrew onboard after it started developing optionally crewed aircraft, like the B-21 Raider.5 An
emerging class of UAS is loitering munitions—also called “kamikaze drones”—which serve as a
single use aircraft flying for extended periods of time (from dozens of minutes to potentially
hours) that can observe and engage targets. This report uses the terms crewed and uncrewed to
distinguish between different types of aircraft, and the term UAS for the broader system.
Current Roles of UAS6
Since the introduction of more sophisticated UAS in the 1990s,7 UAS have performed several
types of missions that were previously performed solely by crewed platforms. These missions
include cargo and resupply; intelligence, surveillance, and reconnaissance; close air support;
communications relay; and aerial refueling. The following sections describe how and why the
military selected UAS to perform these roles.
Intelligence, Surveillance, and Reconnaissance (ISR)8
UAS initially gained prominence in U.S. military operations by performing intelligence,
surveillance, and reconnaissance missions. Although the United States has operated intelligence,
surveillance, and reconnaissance (ISR) UAS since the 1960s, the United States’ use of UAS for
such missions became more widespread with General Atomics’ development of the MQ-1
1 This section was written by John R. Hoehn, Analyst in Military Capabilities and Programs.
2 For more information on UAS programs, see CRS Report R47067, Unmanned Aircraft Systems: Current and
Potential Programs, by John R. Hoehn and Paul K. Kerr.
3 This arrangement is applicable for the larger UAS. For smaller UAS, there is typically a single aircraft with a single
ground control system.
4 Department of Defense, “Air Force Officials Hold a Press Briefing on FY23 Air Force Budget, March 28, 2022,”
press release, March 28, 2022, https://www.defense.gov/News/Transcripts/Transcript/Article/2981330/air-forceofficials-hold-a-press-briefing-on-fy23-air-force-budget-march-28-2022/.
5 For more information on the B-21, see CRS Report R44463, Air Force B-21 Raider Long-Range Strike Bomber, by
Jeremiah Gertler.
6 This section was written by John R. Hoehn, Analyst in Military Capabilities and Programs.
7 For a detailed discussion of these sophisticated UAS, see CRS Report R47067, Unmanned Aircraft Systems: Current
and Potential Programs, by John R. Hoehn and Paul K. Kerr.
8 For a more detailed discussion of the role of intelligence, surveillance, and reconnaissance in targeting, see Appendix
“Intelligence Support of UAS Targeting in Counterterrorism Operations.”
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Predator—then designated as the RQ-1 Predator—in the 1990s. The military’s deployment of
UAS in conflicts such as Kosovo (1999), Iraq (2003-present), and Afghanistan (2001-present) has
illustrated the advantages and disadvantages of uncrewed aircraft, as discussed below.9
The United States military primarily used MQ-1 UAS for reconnaissance and acquisition of
potential ground targets in these conflicts. To accomplish this mission, the aircraft operated with a
450-pound surveillance payload, which included two electro-optical (E-O) cameras and one
infrared (IR) camera for use at night.10 Since the MQ-1, several iterations of UAS, including the
MQ-9 Reaper, have included more sophisticated ISR sensors. Uncrewed aircraft, like the RQ-4
Global Hawk UAS (Figure 1), also fly at higher altitudes and use sophisticated signals
intelligence payloads and synthetic aperture radars.11 Demand for ISR UAS has increased as
DOD has procured larger fleets of aircraft.12 DOD officials and defense analysts state that
combatant commanders routinely request more ISR aircraft—in particular UAS, due to their
ability to fly for long durations.13 As the United States has withdrawn from conflicts around the
world, the military has increasingly relied on UAS to provide ISR and targeting. For a more
detailed discussion on the limitations of UAS targeting in counterterrorism operations, see
Appendix.
9 Although the United States withdrew ground forces from Afghanistan in 2021, it continues to operate UAS there as
part of its “over the horizon” capability to monitor events. For a more detailed discussion, see the Appendix.
10 U.S. Air Force, “MQ-1B Predator,” press release, September 2015, at https://www.af.mil/About-Us/Fact-Sheets/
Display/Article/104469/mq-1b-predator/; and Thomas P. Ehrhard, Air Force UAVs: The Secret History, July 2010, p.
52, at https://apps.dtic.mil/sti/pdfs/ADA526045.pdf.
11 U.S. Air Force, “RQ-4 Global Hawk Fact Sheet,” press release, October 2014, at https://www.af.mil/About-Us/FactSheets/Display/Article/104516/rq-4-global-hawk/.
12 Todd Harrison, Rethinking the Role of Remotely Crewed Systems in the Future Force, Center for Strategic and
International Security, Washington, DC, March 3, 2021, at https://csis-website-prod.s3.amazonaws.com/s3fs-public/
publication/210303_Harrison_Crewed_Systems.pdf?.jvtWe9BQCElgNfXzzhtirSwpKAwadDH.
13 Written testimony of Air Combat Command Commander General Herbert J. Carlisle, in U.S. Congress, Senate
Committee on Armed Services Subcommittee on Airland, hearings, 114th Cong., 2nd sess., March 16, 2016, at
https://www.armed-services.senate.gov/imo/media/doc/Carlisle_03-16-16.pdf. See also Todd Harrison, Rethinking the
Role of Remotely Crewed Systems in the Future Force, Center for Strategic and International Studies, Washington, DC,
March 2021, p. 7, at https://csis-website-prod.s3.amazonaws.com/s3fs-public/publication/
210303_Harrison_Crewed_Systems.pdf?.jvtWe9BQCElgNfXzzhtirSwpKAwadDH.
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Figure 1. RQ-4 Global Hawk UAS Landing in Guam
Source: U.S. Air Force photo/Staff Sgt. Nathan Lipscomb, available at https://www.af.mil/News/Photos/igphoto/
2002864268/mediaid/5476588/.
Note: An RQ-4 Global Hawk from Andersen Air Force Base, Guam, lands at Misawa Air Base, Japan, May 24,
2014.
Close Air Support (CAS)
DOD has expanded the air-to-ground strike mission of UAS to include close air support (CAS).
DOD defines CAS as “[a]ir action by aircraft against hostile targets that are in close proximity to
friendly forces and that require detailed integration of each air mission with the fire and
movement of those forces.”14 Because of the high risks that CAS poses to friendly forces on the
ground due to such proximity, CAS was traditionally performed by crewed platforms, such as the
A-10 Thunderbolt II.15 During operations in Iraq, Afghanistan, and Syria over the past decade,
however, the mission set of MQ-9 Reapers has evolved to perform CAS.16
As an example of UAS performing CAS, on February 21, 2001, the Air Force launched an AGM114 Hellfire missile from what was then called an RQ-1 Predator UAS (Figure 2), marking the
first use of strike UAS. 17 A strike UAS has the capability to launch weapons, such as precision
guided missiles against a target. The Air Force’s use of the MQ-1 expanded considerably during
14 Department of Defense, DOD Dictionary of Military and Associated Terms as of March 2017, p. 38, at
https://www.tradoc.army.mil/wp-content/uploads/2020/10/AD1029823-DOD-Dictionary-of-Military-and-AssociatedTerms-2017.pdf.
15 According to the Air Force the A-10C Thunderbolt II is a “simple, effective and survivable twin-engine jet aircraft
that can be used against light maritime attack aircraft and all ground targets, including tanks and other armored
vehicles. U.S. Air Force, “A-10C Thunderbolt II,” press release, December 2020, at https://www.af.mil/About-Us/FactSheets/Display/Article/104490/a-10c-thunderbolt-ii/.
16 For example, the Air Force states that one of the MQ-9’s missions is close air support. The MQ-9’s other stated
missions include ISR, combat search and rescue, precision strike, convoy and raid overwatch, route clearance, target
development, and terminal air guidance. United States Air Force, “MQ-9 Fact Sheet,” press release, March 2021, at
https://www.af.mil/About-Us/Fact-Sheets/Display/Article/104470/mq-9-reaper/.
17 In 2002, the Air Force redesignated the Predator “MQ-1,” denoting its multirole mission set (i.e., its ability to
provide both ISR and strike capabilities). Air Force News Service, “Predator Missile Launch Test Totally Successful,”
press release, February 26, 2001, at https://web.archive.org/web/20120926012651/http://www.dau.mil/pubscats/
PubsCats/PM/articles01/afns1m-a.pdf. For more information on the capabilities of an AGM-114 Hellfire, see CRS
Report R45996, Precision-Guided Munitions: Background and Issues for Congress, by John R. Hoehn.
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the wars in Iraq (2003-2010) and Afghanistan (2001-2021). Following the MQ-1’s demonstrated
operational capabilities, both the Army and the Air Force developed variants of the UAS,
including the MQ-1C Gray Eagle and the MQ-9 Reaper. These aircraft leveraged the original
MQ-1 airframe while increasing engine power and armament. Both the MQ-1C Gray Eagle and
the MQ-9 Reaper can employ AGM-114 Hellfire missiles, along with GPS-guided and laserguided bombs.
Figure 2. Air Force MQ-1 Predator Armed with a Hellfire Missile
Source: An MQ-1 Predator armed with an AGM-114 Hellfire missile flies a training mission. U.S. Air Force,
available at https://www.af.mil/About-Us/Fact-Sheets/Display/Article/104469/mq-1b-predator/.
Analysts have debated whether UAS should perform CAS missions. Some argue that ground
force troops may not trust UAS to perform these types of missions without harm to friendly
forces.18 According to these analysts, ground troops are more comfortable having a person in the
cockpit performing CAS with eyes on the ground to ensure there is no firing on a friendly
location. Other analysts, however, argue that UAS are well suited for the CAS mission.19 They
state that most general purpose forces have not had sufficient exposure to UAS platforms when
requiring air support (and instead have had more experience with crewed platforms), and these
troops, therefore, are more comfortable with crewed CAS missions. These analysts additionally
note that, unlike general purpose forces, special operations forces have directed a significant
number of uncrewed close air support missions in Iraq and Syria and therefore may be more
comfortable calling upon UAS when available.
Communications Relay
During Operation Enduring Freedom, ground forces identified challenges with operating their
line-of-sight communications systems in mountainous terrain, which limited the distance that
18 Jacqueline Schneider and Julia MacDonald, “Why Troops Don't Trust Drones: The ‘Warm Fuzy’ Problem,” Foreign
Affairs, December 20, 2017, at https://www.foreignaffairs.com/articles/united-states/2017-12-20/why-troops-dont-trustdrones.
19 Cory T. Andersen, Dave Blair, Mike Byrnes, et al., “Trust, Troops, and Reapers: Getting ‘Drone’ Research Right,”
War on the Rocks, April 3, 2018, at https://warontherocks.com/2018/04/trust-troops-and-reapers-getting-droneresearch-right/.
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radio frequencies can travel. In response, in 2008, the Air Force fielded the Battlefield Airborne
Communications Node (BACN) to provide a relay for both voice communications and tactical
datalinks.20 The Air Force selected the crewed E-11A—a modified Bombardier Global XRS/6000
series aircraft—as well as older RQ-4 Global Hawk aircraft (subsequently designated the EQ-4)
to perform this function due to their long endurance and ability to fly at relatively high altitudes.
The first EQ-4s were received the BACN communications payload in 2012,21 and were retired in
FY2021.22
Figure 3. EQ-4
Source: The EQ-4 Global Hawk UAS on its first flight after being converted to carry the BACN on February 16,
2018. Northrop Grumman, available at https://news.northropgrumman.com/news/releases/northrop-grummandelivers-bacn-equipped-global-hawk-to-air-force.
Potential Roles and Missions for UAS23
This section discusses potential UAS roles and missions in future military operations. These
include aerial refueling, air-to-air combat, combat search and rescue, strategic bombing, battle
management command and control, suppression and destruction of enemy air defenses, and
electronic warfare.
Aerial Refueling
Using UAS to refuel other aircraft while airborne, especially in locations far away from airbases,
can potentially reduce the threat to crewed tankers. The Navy is procuring the MQ-25 Stingray
20 Air Combat Command, “Battlefield Airborne Communications Node (BACN),” press release, at
https://www.acc.af.mil/About-Us/Fact-Sheets/Display/Article/2241383/battlefield-airborne-communications-nodebacn/.
21 IHS Janes, “Airborne Communications – Battlefield Airborne Communications Node (BACN),” May 18, 2021,
https://customer.janes.com/Janes/Display/JC4IA305-JC4IA.
22 Department of Defense, FY2022 U.S. Aircraft Procurement Volume II, RQ-4 Mods, pp. 425-451.
23 This section was written by John R. Hoehn, Analyst in Military Capabilities and Programs, and Jeremiah Gertler,
former Specialist in Military Aviation.
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carrier-based UAS for such operations.24 In addition, the Defense Advanced Research Projects
Agency (DARPA) has also conducted research to test the suitability of RQ-4 Global Hawk UAS
aircraft as long endurance refueling platforms, but the military services have yet to develop
formal requirements for this role.25
Air-to-Air Combat
Some relatively early concepts of military UAS sought to carry out fighter operations, engaging
with and destroying enemy aircraft. For example, the Navy’s Unmanned Carrier-Launched
Surveillance and Strike (UCLASS) program intended to develop light-strike capabilities (i.e.,
using small aircraft to attack targets) in a fighter-sized UAS.26 More recently, demonstrator
programs like the Boeing Loyal Wingman seek to add air combat into the mix of fighter aircraft.27
Some recent concepts see uncrewed aircraft operating adjacent to and in coordination with
conventional fighters, taking direction from crewed counterparts or autonomously engaging in
operations to protect the crewed aircraft. This teaming concept is the focus of the U.S. Air Force
Skyborg program (discussed below) and the Airpower Teaming System, which is undergoing
trials in Australia.28 Other concepts rely on a more autonomous model, with uncrewed fighters
clearing airspace ahead of attacking crewed fighters or bombers. As with current fighter jets,
autonomous combat UAS will seemingly need to be able to discriminate between friendly and
hostile aircraft, although other sensor and battle management systems could supply target
designation.29
Combat Search and Rescue/Casualty Evacuation
Locating and recovering downed personnel, known as search and rescue, as well as aerial
casualty evacuation, may involve extended periods of time in high-threat environments. Due to
their endurance and reduced size (i.e., no crew), UAS may be well suited for carrying out search
missions without being detected or requiring crew relief. In addition, military leaders may
potentially accept a greater risk of attrition for UAS in these situations. Such factors could enable
the military to station UAS closer to front lines than crewed aircraft, potentially reducing the time
needed to locate and evacuate personnel. Rotary-wing UAS would be especially well suited for
combat search and rescue/casualty evacuation missions, because DOD currently uses crewed
rotary-wing aircraft (helicopters) for such missions.30 Although UAS could seemingly reduce the
24 CRS Report R47067, Unmanned Aircraft Systems: Current and Potential Programs, by John R. Hoehn and Paul K.
Kerr.
25 DARPA, “Autonomous High-Altitude Refueling,” press release, at https://www.darpa.mil/about-us/timeline/
autonomous-highaltitude-refueling.
26 CRS Report R44131, History of the Navy UCLASS Program Requirements: In Brief, by Jeremiah Gertler.
27 Boeing Australia, “Boeing Loyal Wingman Uncrewed Aircraft Completes First Flight,” press release, March 2, 2021,
at https://www.boeing.com.au/news/releases/2021/march/boeing-loyal-wingman-uncrewed-aircraft-completes-firstflight.page.
28 Boeing, “Boeing Airpower Teaming System,” press release, at https://www.boeing.com/defense/airpower-teamingsystem/.
29 For example, future UAS could be paired with BMC2 aircraft or crewed fighters like the F-35, leveraging tactical
data links like Link 16 or Multifunction Advanced Data Link (MADL) to designate targets. For example, see Paul
Scharre, “Commanding the Swarm,” War on the Rocks, March 25, 2015, at https://warontherocks.com/2015/03/
commanding-the-swarm/.
30 See, inter alia, Paul Scharre, “Left Behind: Why It’s Time to Draft Robots for CASEVAC,” War on the Rocks,
August 12, 2014, at https://warontherocks.com/2014/08/left-behind-why-its-time-to-draft-robots-for-casevac/; and
Mandy Langfield, “Unmanned K-MAX performs first casevac,” AirMed & Rescue, April 30, 2015, at
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time needed to transport injured personnel to treatment facilities in casualty evacuation missions
where troops on the ground are able to place an injured person on board, the lack of a crew would
prevent the availability of first aid during the flight.31
Cargo and Resupply
DOD has also used UAS in cargo and resupply missions. Notably, the Marine Corps used a UAS
helicopter called the K-MAX for operations in Afghanistan.32 The K-MAX, which was intended
to replace ground convoys, flew autonomously to remote outposts carrying up to 6,000 pounds of
cargo or supplies.33 The Navy has experimented with a smaller Volansi VOLY C10 UAS (Figure
4) to deliver 20 pounds of cargo over 15 miles.34
According to a February 2022 press report, a U.S. ally deployed an uncrewed glider system called
Silent Arrow, which is released from a C-130 Hercules transport aircraft and may deliver up to
1,650 pounds of cargo.35 Silent Arrow is reportedly capable of gliding approximately 40 nautical
miles when released at 25,000 feet. A motorized variant, called the GD-2000, is also reported to
be capable of launching and recovering from improvised runways (i.e., areas that are not
designated to be runways and do not have the requisite improvements, such as pavement and
lighting).36
https://www.airmedandrescue.com/latest/news/unmanned-k-max-performs-first-casevac.
31 See, inter alia, Paul Scharre, “Left Behind: Why It’s Time to Draft Robots for CASEVAC,” War on the Rocks,
August 12, 2014, at https://warontherocks.com/2014/08/left-behind-why-its-time-to-draft-robots-for-casevac/; and
Mandy Langfield, “Unmanned K-MAX performs first casevac,” AirMed & Rescue, April 30, 2015, at
https://www.airmedandrescue.com/latest/news/unmanned-k-max-performs-first-casevac.
32 U.S. Congress, Senate Committee on Armed Services, Subcommittee on Seapower, Marine Corps Ground
Modernization and Naval Aviation Programs, 116th Cong., 1st sess., April 10, 2019, p. 49, at https://www.armedservices.senate.gov/imo/media/doc/19-38_04-10-19.pdf.
33 Matthew Cox, “Marine Corps Wants to Upgrade its K-MAX Pilotless Cargo Helicopters,” Military.Com, April 10,
2019, at https://www.military.com/daily-news/2019/04/10/marine-corps-wants-upgrade-its-k-max-pilotless-cargohelicopters.html.
34 Brett Tingley, “Drone Makes First Autonomous Aerial Delivery Between Two Military Vessels,” The Warzone,
August 4, 2021, at https://www.thedrive.com/the-war-zone/41838/drone-makes-first-autonomous-aerial-deliverybetween-two-military-vessels.
35 Brett Tingley, “Autonomous Resupply Gliders Made Successful Deliveries On Their First Overseas Deployment,”
The War Zone, February 2, 2022, at https://www.thedrive.com/the-war-zone/44111/autonomous-resupply-glidersmade-successful-deliveries-on-their-first-overseas-deployment, and Silent Arrow, “Silent Arrow® Autonomously
Delivers 1,026 Pounds of Cargo,” press release, January 31, 2022, at https://silent-arrow.com/news-%26-media/f/silentarrow%C2%AE-autonomously-delivers-1026-pounds-of-cargo.
36 Brett Tingley, “Autonomous Resupply Gliders Made Successful Deliveries On Their First Overseas Deployment,”
The War Zone, February 2, 2022, at https://www.thedrive.com/the-war-zone/44111/autonomous-resupply-glidersmade-successful-deliveries-on-their-first-overseas-deployment.
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Figure 4.Volansi VOLY C10
Source: A Volansi VOLY 10 series vertical takeoff and landing UAS carrying a cargo payload, available at
https://www.thedrive.com/the-war-zone/41838/drone-makes-first-autonomous-aerial-delivery-between-twomilitary-vessels.
Strategic Bombing
The Air Force intends for the next generation of U.S. bombers—such as the B-21 Raider LongRange Strike Bomber—to be optionally crewed, allowing remote operation for conventional
strike missions into heavily defended areas.37 The optionally crewed B-21 aircraft, with an
intercontinental range and large payload, provides a capability distinct from existing strike UAS,
which can strike only small, single-point targets. Optionally crewed aircraft—including the B-21
Raider—38 lack some advantages of uncrewed aircraft, because the optionally crewed aircraft
must include the weight and space necessary for people and their life support.
37See CRS Report R44463, Air Force B-21 Raider Long-Range Strike Bomber, by Jeremiah Gertler, for additional
information on the B-21 aircraft. See also, Tyler Rogoway and Joseph Trevithick, “Document Confirms B-21 To Be
Delivered Optionally Manned And Nuclear Capable,” The War Zone, November 8, 2017, at https://www.thedrive.com/
the-war-zone/15902/document-confirms-b-21-to-be-delivered-optionally-manned-and-nuclear-capable. U.S. doctrine
requires aircraft on nuclear missions to be manned. For more information on U.S. strategic forces, see CRS Report
RL33640, U.S. Strategic Nuclear Forces: Background, Developments, and Issues, by Amy F. Woolf.
38 Northrop Grumman, “Northrop Grumman’s Optionally-Manned Firebird Demonstrates Operational Flexibility,”
press release, April 6, 2021, at https://news.northropgrumman.com/news/releases/northrop-grummans-optionallymanned-firebird-demonstrates-operational-flexibility and https://www.aurora.aero/centaur-optionally-piloted-aircraft/.
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Battle Management Command and Control (BMC2)
Current BMC2 platforms, such as the E-3 Sentry AWACS and E-8 JSTARS,39 carry an array of
sensors and a crew to translate those sensor inputs and direct friendly aircraft and forces.40
Current concepts for replacing the E-3 focus on crewed platforms.41 Including the same sensor
suite on an uncrewed platform, with the operational crew on the ground or in another aircraft but
receiving the same sensor inputs, could reduce the potential threat to the crew.42
Some UAS also operate at significantly higher altitudes than current crewed systems, increasing
the area their sensors can cover and improving survivability.43 The longer endurance of some
UAS likely improves mission efficiency by requiring fewer aircraft to maintain the same
coverage.
Suppression and Destruction of Enemy Air Defenses
Suppression and destruction of enemy air defenses is the first and most dangerous part of an air
campaign, because attacking aircraft generally face enemy air defense networks at their full
capability. In addition to expendability, UAS offer a number of advantages for such missions.
Large numbers of small UAS engaging enemy air defenses could overwhelm these defenses and
compel an adversary to use many of its weapons against small, comparatively low-value targets.
Such swarming tactics—discussed in greater detail below—could also direct many attacking
aircraft to the target and confuse responders.44 Because most modern air defense systems are
designed for combatting crewed aircraft, UAS could create a novel problem for enemy forces,
particularly when operated in unconventional ways. These methods include rapid changes in
speed or direction, or high g-loadings (i.e., the amount of forces the aircraft encounters) that
39 According to the Air Force, the E-3 Sentry “AWACS provides situational awareness of friendly, neutral and hostile
activity, command and control of an area of responsibility, battle management of theater forces, all-altitude and allweather surveillance of the battle space, and early warning of enemy actions during joint, allied, and coalition
operations.” The Air Force states the E-8 JSTARS primary mission “is to provide theater ground and air commanders
with ground surveillance to support attack operations and targeting that contributes to the delay, disruption and
destruction of enemy forces.” U.S. Air Force , “E-3 Sentry (AWACS),” press release, September 2015, at
https://www.af.mil/About-Us/Fact-Sheets/Display/Article/104504/e-3-sentry-awacs/, and U.S. Air Force, “E-8C Joint
Stars,” press release, September 2015, at https://www.af.mil/About-Us/Fact-Sheets/Display/Article/104507/e-8c-jointstars/.
40 See CRS Report R44108, U.S. Command and Control and Intelligence, Surveillance, and Reconnaissance Aircraft.
41 See CRS In Focus IF12045, Replacing the E-3 Airborne Warning and Control System (AWACS), by John R. Hoehn
and Jeremiah Gertler.
42 Lawrence A. Stutzriem, Reimagining the MQ-9 Reaper, Mitchell Institute, V. 30, Arlington, VA, November 2021, at
http://mitchellaerospacepower.org/wp-content/uploads/2021/11/Reimagining_the_MQ-9_Reaper_Policy_Paper_301.pdf.
43 Operating at higher altitudes increases survivability because the aircraft continues to fly at a relatively fast rate,
requiring an air defense missile to intercept at a longer range than would be required for a medium-altitude intercept.
This is a similar trait to using satellites like the Global Positioning System to enable radio navigation. H. M. J.
Cantalloube, “High altitude terrain correlation navigation resetting by nadir looking synthetic aperture radar,” Progress
In Electromagnetics Research Symposium, 2017, pp. 3252-3257, at https://ieeexplore.ieee.org/document/8262318.
Cemil Tepeck and Isa Navruz, “The effects of frequency and altitude on radar performance with surface ducting,” 22 nd
Signal Processing and Communications Applications Conference (SIU), 2014, pp. 2202-2205, at
https://ieeexplore.ieee.org/document/6830701. At certain altitudes, aircraft are out-of-range of ground-based air defense
systems.
44 Paul Scharre, Robotics on the Battlefield Part II: The Coming Swarm, Center for New American Security,
Washington, DC, October 2014, at https://s3.us-east-1.amazonaws.com/files.cnas.org/documents/
CNAS_TheComingSwarm_Scharre.pdf?mtime=20160906082059&focal=none.
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would not be possible with a human aboard.45 In addition, electronic measures can make UAS to
appear as larger, more threatening aircraft to radar and other sensors, further complicating a
defender’s responses.46
Electronic Warfare47
Uncrewed aircraft could also serve as electronic warfare platforms,48 designed to be outfitted with
radio frequency jamming equipment capable of interfering with adversary electronics.
Expendable UAS could be more favorable to use in electronic warfare because jamming
equipment requires sufficient power to interfere with electronic equipment. As a result, when an
aircraft is jamming an adversary’s radio frequency, its electromagnetic signature increases. An
adversary, consequently, can detect electronic warfare aircraft more easily than regular aircraft
that do not emit high-power radio frequencies. Uncrewed aircraft could therefore mitigate the risk
posed to crewed aircraft should potential adversaries destroy the aircraft in response to the effects
of jamming.
Although the United States has not publicly discussed using uncrewed aircraft for electronic
warfare, DOD has developed cruise missiles for this mission, which are essentially designed as
single-use aircraft. The Air Force, for example, developed the Miniature Air Launched Decoy
(MALD) and the Miniature Air Launched Decoy-Jammer (MALD-J), air-launched cruise missiles
designed to mimic larger aircraft radar signatures and modified to jam adversary integrated air
defenses.49 Some analysts have speculated that UAS could similarly serve in electronic warfare
capacities.50
45
Ibid.
46 Raytheon Missiles & Defense, “MALD Decoy,” press release, at https://www.raytheonmissilesanddefense.com/
what-we-do/naval-warfare/advanced-strike-weapons/mald-decoy.
47 For additional information about electronic warfare, see CRS In Focus IF11118, Defense Primer: Electronic
Warfare, by John R. Hoehn.
48 For more information on airborne electronic warfare, see CRS Report R44572, U.S. Airborne Electronic Attack
Programs: Background and Issues for Congress, by John R. Hoehn.
49 U.S Air Force, FY2017 Aircraft Procurement Line Item 76 War Consumables, at https://apps.dtic.mil/procurement/
Y2017/AirForce/U_P40_76_BSA-4_BA-7_APP-3010F_PB_2017.pdf.
50 Mark Gunzinger, Sustaining America’s Strategic Advantage in Long-Range Strike, Center for Strategic and
Budgetary Assessments, Washington, DC, September 14, 2010, p. 69, at https://csbaonline.org/uploads/documents/
2010.09.14-Sustaining-Americas-Strategic-Advantage-in-Long-Range-Strike.pdf.
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Figure 5. ADM-160A Miniature Air-Launched Decoy (MALD)
Source: Raytheon Technologies, available at https://www.raytheonmissilesanddefense.com/capabilities/products/
mald-decoy.
Advantages and Disadvantages of Unmanned Aircraft Systems
UAS offer both advantages and disadvantages when compared with crewed aircraft, including
differences in aircraft performance, risk tolerances associated with UAS operations, and
communications requirements, as discussed below.
Aircraft Performance
A primary difference between crewed and uncrewed aircraft is the performance characteristics of
each. Improved engineering techniques enable aircraft designs limited mostly by
accommodations and safety for human pilots, rather than by material or structural elements.51 For
example, uncrewed aircraft do not require cockpits, life support, or other systems necessary for
crewed aircraft.52 The absence of these elements reduces the weight of uncrewed aircraft and may
enable different, more aerodynamically unstable aircraft designs.53 As a result, uncrewed aircraft
can fly for longer periods of time (limited by the oil lubricants in the engine) and potentially fly at
higher speeds and handle more g-forces—a measure of acceleration (a factor in determining
aircraft maneuverability)—than humans could tolerate.54
51 Department of Defense, Unmanned Systems Roadmap 2007-2032, Washington, DC, December 10, 2007, pp. 19-20,
at https://rosap.ntl.bts.gov/view/dot/18247.
52 Life support systems include oxygen systems, cabin pressurization, and ejection seats.
53 Unstable aircraft design means the aircraft would leave controlled flight without direct control inputs. Aircraft like
the B-2 Sprit would be unable to fly without flight control computers providing constant inputs to maintain controlled
flight. Paul Scharre, Robotics on the Battlefield: Part I: Range, Persistence, and Daring, Center for New American
Security, Washington, DC, May 21, 2014, p. 10, at https://www.cnas.org/publications/reports/robotics-on-thebattlefield-part-i-range-persistence-and-daring.
54 Department of Defense, Unmanned Systems Roadmap 2007-2032, Washington, DC, December 10, 2007, pp. 19-20,
https://rosap.ntl.bts.gov/view/dot/18247. See also Paul Scharre, Robotics on the Battlefield: Part I: Range, Persistence,
and Daring, Center for New American Security, Washington, DC, May 21, 2014, https://www.cnas.org/publications/
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Risk Tolerances
UAS platforms incur different types of risk than traditional crewed platforms. Among other
factors, UAS appear to have a higher propensity to be involved in a Class A mishap (DOD defines
a Class A mishap as causing $2.5 million or more worth of damage, the total destruction of an
aircraft, or an accident resulting in a fatality).55 Because UAS are involved in Class A mishaps
more often, military planners would likely need to include more UAS in the force structure than
comparable numbers of crewed aircraft. The risks of potential adversaries gaining access to
advanced U.S. military technologies could also increase, due to more potential mishaps in enemyheld areas. In some instances, crewed aircraft have bombed UAS crash sites to prevent
adversaries from examining U.S. technologies.56
These risks of technological exploitation, however, may be offset by the reduced risk to personnel
and the attendant decreased demand for retaliatory strikes. Some analysts argue that UAS reduce
the risk of potential escalation.57 These analysts state “emerging norms regarding the
consequences of shooting down a drone, though clearly still in the early stages, suggest that states
distinguish between the shooting down of manned and unmanned systems.”58 Iran shot down a
Navy MQ-4C UAS in the Persian Gulf in 2019. According to a Navy press briefing, the aircraft
was flying in the area to monitor the Strait of Hormuz for Iranian threats to commercial shipping.
DOD officials characterized the attack as “an attempt to disrupt our ability to monitor the area
following recent threats to international shipping and free flow of commerce.”59 The Trump
Administration at the time reportedly contemplated retaliatory strikes on Iran for destroying a
U.S. aircraft, but seemingly determined to not respond.60 Similarly, the Air Force reportedly flew
an RQ-170 UAS in Pakistan in 2011 during the special operations raid on Osama bin Laden.61
During this operation, the RQ-170 operated in “contested airspace” in which the Pakistani
military operated sophisticated air defenses.62 The decision to use an uncrewed platform might
have been made, in part, to reduce the risk of military casualties.
reports/robotics-on-the-battlefield-part-i-range-persistence-and-daring.
55 CRS Report R47067, Unmanned Aircraft Systems: Current and Potential Programs, by John R. Hoehn and Paul K.
Kerr, and Department of Defense, Mishap Notification, Investigation, Reporting, and Record Keeping, DoDI 6055.07,
Washington, DC, June 6, 2011, at https://www.esd.whs.mil/Portals/54/Documents/DD/issuances/dodi/605507p.pdf..
56 For example, see U.S. Air Forces Central Command, “MQ-9 crashes in northern Syria,” press release, July 5, 2016,
https://www.af.mil/News/Article-Display/Article/823888/mq-9-crashes-in-northern-syria/platform/hootsuite/.
57 Michael Horowitz, “Separating Fact from Fiction in the Debate over Drone Proliferation,” International Security,
vol. 41, no. 2 (Fall 2016), pp. 7-42, https://direct.mit.edu/isec/article/41/2/7/12140/Separating-Fact-from-Fiction-in-theDebate-over.
58 Ibid.
59 U.S. Air Forces Central Command, “MQ-9 crashes in northern Syria,” press release, July 5, 2016, at
https://www.af.mil/News/Article-Display/Article/823888/mq-9-crashes-in-northern-syria/platform/hootsuite/.
60 Michael D. Shear et al., “Strikes on Iran Approved by Trump, Then Abruptly Pulled Back,” New York Times, June
20, 2019, at https://www.nytimes.com/2019/06/20/world/middleeast/iran-us-drone.html.
61 “RQ-170 Stealth Drone Used in Bin Laden Raid,” Military.Com, May 18, 2011, at https://www.military.com/
defensetech/2011/05/18/rq-170-sentinel-stealth-drone-used-in-bin-laden-raid..https://www.military.com/defensetech/
2011/05/18/rq-170-sentinel-stealth-drone-used-in-bin-laden-raid.
62 Pakistani air defenses at the time included the Soviet-developed SA-2 and the French-developed Crotale missile.
International Institute for Strategic Studies, Military Balance 2012, London, UK, March 2012, p. 274.
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Communications Requirements63
Another design difference between crewed and uncrewed aircraft is the need for secure
communications (i.e., encrypted radios) to control uncrewed aircraft.64 UAS require a human
operator to control its flight and its weapons capabilities.65 Depending on the UAS mission, two
types of communications may be required. For operations flying within approximately 50 miles
from a home base, line-of-sight communications may be used, typically when UAS take off or
land, since there is no time delay. Aircraft flying beyond 50 miles from a home base require
beyond-line-of-sight (BLOS) communications—which in turn require links to satellite
communications. Although crewed aircraft similarly rely on communications to coordinate
operations, such aircraft do not need constant communications systems to maintain controlled
flight.66
One potential risk to UAS is the disruption or jamming of control communications by
adversaries.67 To mitigate risks to the aircraft due to enemy jamming, some UAS can be
programmed to return to their home base using global position system (GPS) navigation if their
control signal is jammed. Another potential risk associated with UAS operations is an adversary
hacking the aircraft to perform a different mission. In this scenario, an adversary would conduct a
cyberattack (using radio frequencies) on the aircraft to enable the adversary to gain control of it.68
Most military UAS, finally, rely on GPS signals for navigation. If an adversary were to jam GPS
signals, the UAS may be unable to navigate to its intended destination.
Experimental Concepts69
In addition to existing DOD concepts of operation for UAS, a number of experimental concepts
relating to the future use of UAS are in development. These include system-of-systems, artificial
intelligence (AI)-enabled manned-unmanned teaming, swarming, and lethal autonomous weapon
systems. Although discussed separately below, these concepts will likely overlap as they—and the
technologies associated with them—mature.70
63 For a more detailed discussion of communications, see CRS Report R46564, Overview of Department of Defense
Use of the Electromagnetic Spectrum, coordinated by John R. Hoehn.
64 While encrypted radio signals were not an initial requirement for UAS operations, U.S. forces found Iraqi insurgents
were gaining access to unencrypted MQ-1 Predator video feeds. As a result, U.S. forces began encrypting these signals
to prevent adversaries from gaining access to U.S. intelligence. Mike Mount and Elaine Quijano, “Iraqi insurgents
hacked Predator drone feeds, U.S. official indicates,” CNN, December 17, 2009, at http://www.cnn.com/2009/US/12/
17/drone.video.hacked/index.html.
65 U.S. Air Force, Flight Operations, Air Force Manual (AFMAN) 11-202 Volume 3, Washington, DC, January 10,
2022, p. 270, at https://static.e-publishing.af.mil/production/1/af_a3/publication/afman11-202v3/afman11-202v3.pdf.
66
Uncrewed aircraft can be programmed to fly a specific route, potentially reducing the need for satellite
communications to maintain control; however, these systems still require GPS for navigation purposes. Crewed aircraft
can operate with paper maps and therefore theoretically operate without any communications systems.
67 For a more detailed discussion of electronic warfare, see CRS In Focus IF11118, Defense Primer: Electronic
Warfare, by John R. Hoehn.
68 For a broader discussion of the convergence between cyber and electronic warfare, see CRS In Focus IF11292,
Convergence of Cyberspace Operations and Electronic Warfare, by Catherine A. Theohary and John R. Hoehn.
69 This section was written by Kelley M. Sayler, Analyst in Advanced Technology and Global Security.
70 For example, any UAS—including lethal autonomous weapons and the platforms discussed in the “AI-Enabled
Manned-Unmanned Teaming” section of this report (e.g., Skyborg, Valkyrie)—could potentially be integrated into a
system-of-systems or swarm.
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Aircraft System-of-Systems
System-of-systems (SOS) refers to “a collection of systems, each capable of independent
operation, that interoperate together to achieve additional desired capabilities.”71 These systems
may be deployed on separate aircraft, including crewed, optionally crewed, and uncrewed
aircraft. For example, although little open-source information exists about the Next Generation
Air Dominance (NGAD) program, DOD reportedly intends for NGAD to enable air superiority
through a “portfolio of technologies” that forms an SOS.72 Secretary of the Air Force Frank
Kendall has stated that NGAD “will include a crewed platform teamed with a much less
expensive, autonomous, uncrewed combat aircraft employing a distributed, tailorable mix of
sensors, weapons, and other mission equipment.”73 This approach would allow commanders to
compose aircraft packages for each mission to mitigate risk and maximize the likelihood of
mission success. The SOS approach is additionally intended to allow spiral software
development, in which NGAD software and hardware can be continuously upgraded or
replaced.74
AI-Enabled Manned-Unmanned Teaming
Manned-unmanned teaming (MUMT) pairs crewed aircraft with uncrewed aircraft to leverage the
strengths of each. The U.S. military has previously fielded MUMT applications involving
remotely piloted UAS;75 however, it is now exploring more advanced, AI-enabled MUMT
applications in which one or more UAS operate in conjunction with—but autonomously from—
crewed aircraft. These applications include mission support and autonomous dogfighting, or airto-air combat maneuvering.
Mission Support
UAS may be employed in a mission support role for crewed aircraft, a concept that is often
referred to as “loyal wingman.” The Air Force program Skyborg is intended to support this
concept and expected to develop UAS capable of autonomously collecting data and performing
other missions—such as target identification and electronic warfare—to increase the situational
awareness and lethality of crewed aircraft.76 According to a 2020 Air Force contracting notice,
71 See MITRE, “Systems Engineering Guide: System of Systems,” at https://www.mitre.org/publications/systems-
engineering-guide/enterprise-engineering/systems-of-systems.
72 Department of Defense, Fiscal Year (FY) 2022 Budget Estimates, Air Force Justification Book of Research,
Development, Test and Evaluation, Volume II, p. 335, at https://www.saffm.hq.af.mil/Portals/84/documents/FY22/
RDTE_/FY22%20DAF%20J-Book%20-%203600%20-%20AF%20RDT%20and%20E%20Vol%20II.pdf?ver=
KpJJbVq68o32dSvkjuv_Iw%3d%3d.
73 John A. Tirpak, “Details Emerge on New Unmanned Long-Range Bomber and Fighter Projects,” Air Force
Magazine, March 3, 2022, at https://www.airforcemag.com/details-emerge-on-new-unmanned-long-range-bomber-andfighter-projects/.
74 John A. Tirpak, “New Force Design: NGAD Needed Soon, F-22 Sunset Begins in 2030,” Air Force Magazine, May
13, 2021, at https://www.airforcemag.com/new-force-design-ngad-needed-soon-f-22-sunset-begins-in-2030/.
75 For example, the Army has fielded AH-64 Apache helicopters with software packages that allow the pilot to control
the flight path and sensors of certain Army UAS. See Belinda Bazinet, “Upgraded Apache helicopters begin fielding to
Soldiers in Korea,” U.S. Army, January 10, 2020, at https://www.army.mil/article/253180/
upgraded_apache_helicopters_begin_fielding_to_soldiers_in_korea.
76 “Skyborg,” Air Force Research Laboratory, at https://afresearchlab.com/technology/vanguards/successstories/
skyborg. One variant, the Off-Board Sensing Station (OBSS), is to “extend a [crewed] fighter’s sensing range and also
potentially carry additional weapons for that aircraft.” John A. Tirpak, “Kratos, General Atomics Get Contracts for
‘Off-Board Sensing Station’ Unmanned Fighter Escort,” Air Force Magazine, October 26, 2021, at
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Skyborg UAS are to be low-cost, reusable platforms with “minimal logistical footprints” to
enable rapid deployment in combat.77 Skyborg is also to feature an “open architecture” design
that allows the modular integration of various sensor, communication, and other technologies.78
Skyborg could be paired with other uncrewed platforms such as Valkyrie, a stealthy, low-cost
UAS that could similarly provide mission support for crewed aircraft. For example, Valkyrie has
been tested as a communications gateway for F-22 and F-35 fighter aircraft.79 The Air Force has
also experimented with using Valkyrie as a launch platform for smaller UAS that could
potentially perform “electronic warfare, signals intelligence, counter-UAS, and intelligence,
surveillance and reconnaissance, and [could] be outfitted to produce kinetic effects”80 (Figure 6).
Valkyrie is reportedly capable of carrying up to four GBU-39B Small Diameter Bombs, a 250pound-class guided air-to-surface weapon.81
https://www.airforcemag.com/kratos-general-atomics-contracts-unmanned-fighter-escort/.
77 Joseph Trevithick, “The Fight For the Air Force’s ‘Skyborg’ Artificial Intelligence Equipped Drones Has Begun,”
The Drive, May 19, 2020, at https://www.thedrive.com/the-war-zone/33567/the-fight-for-the-air-forces-skyborgartificial-intelligence-equipped-drones-has-begun.
78 Department of Defense, Fiscal Year (FY) 2022 Budget Estimates, Air Force Justification Book of Research,
Development, Test and Evaluation, Volume I, p. 214, at https://www.saffm.hq.af.mil/Portals/84/documents/FY22/
RDTE_/FY22_PB_RDTE_Vol-I.pdf?ver=DGijGVofWq4jnTnOLuU5Bg%3d%3d.
79 The F-22 and F-35 are equipped with two different low-probability-of-intercept/low-probability-of-detection
(LPI/LPD) systems for exchanging data in stealth mode, and thus cannot communicate directly over LPI/LPD systems.
Joseph Trevithick, Thomas Newdick, and Tyler Rogoway, “Stealthy XQ-58 Drone Busts The Networking Logjam
Between F-22 And F-35,” The Drive, December 15, 2020, at https://www.thedrive.com/the-war-zone/38168/stealthyxq-58-drone-busts-the-networking-logjam-between-f-22-and-f-35.
80 Valerie Insinna, “Valkyrie drone launches even smaller drone from inside payload bay,” Defense News, April 5,
2021, at https://www.defensenews.com/air/2021/04/05/the-valkyrie-drone-launches-an-even-smaller-drone-frominside-its-payload-bay/.
81 Brett Tingley and Tyler Rogoway, “Kratos Says Secret ‘Off-Board Sensing Station’ Unmanned Aircraft Will Be
Transformative, The Drive, August 5, 2021, at https://www.thedrive.com/the-war-zone/41849/kratos-says-secret-offboard-sensing-station-unmanned-aircraft-will-be-transformative. For additional information about the capabilities of
the GBU-39B Small Diameter Bomb, see U.S. Air Force, “GBU-39B Small Diameter Bomb Weapon System,” at
https://www.af.mil/About-Us/Fact-Sheets/Display/Article/104573/gbu-39b-small-diameter-bomb-weapon-system/.
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Figure 6. Valkyrie UAS Deploys ALTIUS-600 Small UAS
Source: U.S. Air Force, available at https://www.af.mil/News/Photos/igphoto/2002617611/.
Autonomous Dogfighting
DARPA is currently exploring the concept of autonomous dogfighting—in which artificial
intelligence could be used to conduct air-to-air combat maneuvers—in its Air Combat Evolution
(ACE) program. ACE seeks to “build human trust in AI,” such that a single human pilot may
direct multiple UAS.82 According to DARPA, this outcome could enable a division of labor “in
which higher-level cognitive functions (e.g., developing an overall engagement strategy, selecting
and prioritizing targets, determining best weapon or effect, etc.) may be performed by a human,
while lower-level functions (i.e., details of aircraft maneuver and engagement tactics) [are] left to
the autonomous system.”83
DARPA hosted the AlphaDogfight Trials, which tested AI algorithms that could enable
autonomous dogfighting, in August 2020.84 During the trials, participating teams submitted
algorithms designed to simulate an F-16 fighter jet in air-to-air combat. The top algorithm was
then tested against an Air Force fighter pilot flying an F-16 simulator, with the algorithm winning
all five simulated dogfights due to its ability to make “aggressive and precise maneuvers the
human pilot couldn’t outmatch” or would not undertake due to risk.85 DARPA reportedly plans to
test autonomous dogfighting algorithms in commercial UAS in FY2022 through FY2023 before
transitioning to combat aircraft in FY2023 and FY2024.86
82 “AlphaDogfight Trials Foreshadow Future of Human-Machine Symbiosis,” DARPA, August 26, 2020, at
https://www.darpa.mil/news-events/2020-08-26.
83 “Air Combat Evolution (ACE),” DARPA, at https://www.darpa.mil/program/air-combat-evolution.
84 “AlphaDogfight Trials Foreshadow Future of Human-Machine Symbiosis,” DARPA, August 26, 2020, at
https://www.darpa.mil/news-events/2020-08-26.
85 Ibid.
86 Thomas Newdick, “AI That Bested Air Force Pilot In “Digital Dogfights” Headed For L-39 Jet Trainer,” The Drive,
July 26, 2021, at https://www.thedrive.com/the-war-zone/41683/ai-that-bested-air-force-pilot-in-digital-dogfights-
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Swarming
Swarming refers to cooperative behavior—generally enabled by artificial intelligence and
networked communications—in which a group of UAS autonomously coordinates to accomplish
a mission.87 Notional swarming concepts range from large formations of low-cost UAS that could
overwhelm adversary defensive systems (see the “Suppression and Destruction of Enemy Air
Defenses” section above) to smaller, more tailored formations that could execute electronic attack
or ISR missions. Some analysts argue that swarms could have several advantages over
individually deployed UAS, such as the ability to easily disperse combat power. This ability could
in turn complicate an adversary’s ability to target and neutralize the swarm, thus creating an
unfavorable cost-exchange ratio for the defender.88 Similarly, swarms of low-cost UAS could
provide a less expensive alternative to traditional weapons systems.89 Swarms could also reduce
personnel requirements and costs by enabling a single servicemember to operate numerous UAS
at the same time. Finally, swarms could retain combat power “as individual platforms are attrited,
as opposed to a sharp loss in combat power if a single, more exquisite platform is lost.”90
The U.S. military has a number of swarm programs under development. For example, Low-Cost
UAV (Unmanned Aerial Vehicle) Swarming Technology (LOCUST), an Office of Naval Research
(ONR) program, seeks to mature swarm technology for Raytheon’s portable, tube-launched
Coyote UAS. According to Navy budget documents, ONR has successfully launched 33 Coyote
UAS in 40 seconds and flown them in a “coordinated swarm.”91 Reports indicate that the Coyote
is capable of carrying a variety of different payloads, including electronic warfare systems or
explosive warheads, and could be deployed on a range of ground-, air-, and sea-based platforms.92
DARPA’s OFFensive Swarm-Enabled Tactics (OFFSET) program, which conducted its final field
experiment in December 2021, similarly sought to mature technologies to enable swarms of up to
headed-for-l-39-jet-trainer.
87 Paul Scharre, Robotics on the Battlefield Part II: The Coming Swarm, Center for a New American Security, October
2014, at https://s3.amazonaws.com/files.cnas.org/documents/CNAS_TheComingSwarm_Scharre.pdf.
88 An unfavorable cost-exchange ratio would occur if, in an attempt to neutralize the swarm, the defender uses a
countermeasure (e.g., missile interceptor[s]) with an aggregate cost that is higher than the aggregate cost of the swarm.
For additional information about the relationship between swarms and cost-exchange ratios, see Paul Scharre, Robotics
on the Battlefield Part II: The Coming Swarm, Center for a New American Security, October 2014, pp. 20-21, at
https://s3.amazonaws.com/files.cnas.org/documents/CNAS_TheComingSwarm_Scharre.pdf. An unfavorable costexchange ratio can also occur in countering a single UAS. For example, a U.S. ally reportedly used a $3 million Patriot
surface-to-air missile to shoot down a $200 UAS. See Chris Baraniuk, “Small drone ‘shot with Patriot missile,’” BBC,
March 15, 2017, at https://www.bbc.com/news/technology-39277940.
89 For example, one Patriot surface-to-air missile costs approximately $3 million, while one Coyote UAS costs
approximately $15,000 (without a warhead). A swarm of 100 Coyote UAS would therefore cost approximately half as
much as a Patriot missile, all else being equal. See Joseph Trevithick, “Army Buys Small Suicide Drones To Break Up
Hostile Swarms And Potentially More,” The Drive, July 17, 2018, at https://www.thedrive.com/the-war-zone/22223/
army-buys-small-suicide-drones-to-break-up-hostile-swarms-and-potentially-more#:~:text=
Coyote's%20relatively%20low%20cost%20could,trim%20that%20cost%20back%20further.
90 Paul Scharre, Robotics on the Battlefield Part II: The Coming Swarm, Center for a New American Security, October
2014, p.14, at https://s3.amazonaws.com/files.cnas.org/documents/CNAS_TheComingSwarm_Scharre.pdf.
91 Department of Defense, Fiscal Year (FY) 2022 Budget Estimates, Navy Justification Book of Research,
Development, Test and Evaluation, Volume II, Budget Activity 4, p. 170, at https://www.secnav.navy.mil/fmc/fmb/
Documents/22pres/RDTEN_BA4_Book.pdf.
92 David Hambling, “U.S. Navy Destroys Target With Drone Swarm—And Sends A Message To China,” Forbes, April
30, 2021, at https://www.forbes.com/sites/davidhambling/2021/04/30/us-navy-destroys-target-with-drone-swarm—
and-sends-a-message-to-china/?sh=4c62b0d92df1.
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250 UAS and/or uncrewed ground systems.93 This capability is intended to support military
personnel operating in complex urban environments.94 DARPA is also exploring a concept for a
UAS swarm called Gremlins (Figure 7) that could be launched from—and recovered in-flight
by—a C-130 transport aircraft or other airborne platform.95 Military personnel could then
refurbish and relaunch the Gremlins within 24 hours.96 According to DARPA, “the gremlins’
expected lifetime of about 20 uses could provide significant cost advantages over expendable
systems by reducing payload and airframe costs and by having lower mission and maintenance
costs than conventional platforms, which are designed to operate for decades.”97
Figure 7. Gremlin UAS Swarm
Source: DARPA, available at https://www.darpa.mil/program/gremlins.
Lethal Autonomous Weapon Systems
Although no internationally agreed-upon definition of Lethal Autonomous Weapon Systems
(LAWS) exists, DOD Directive 3000.09 defines LAWS as a class of weapon systems capable of
both independently identifying a target and employing an onboard weapon to engage and destroy
it without manual human control. This concept of autonomy is also known as “human out of the
loop” or “full autonomy.”98 The directive contrasts LAWS with human-supervised, or “human on
93 “OFFensive Swarm-Enabled Tactics (OFFSET),” DARPA, at https://www.darpa.mil/work-with-us/offensive-swarm-
enabled-tactics.
94 Ibid.
95 DARPA reportedly envisions that the Gremlin launch platform (e.g., C-130 transport aircraft) would “stay out of
range of enemy air defenses,” while the Gremlin swarm would “fly into danger and conduct missions such as
intelligence, surveillance, reconnaissance or electronic warfare” before returning to the launch platform. See Stephen
Losey, “DARPA nabs Gremlin drone in midair for first time,” Defense News, November 5, 2021, at
https://www.defensenews.com/unmanned/2021/11/05/darpa-nabs-gremlin-drone-in-midair-for-first-time/.
96 Stephen Losey, “DARPA nabs Gremlin drone in midair for first time,” Defense News, November 5, 2021, at
https://www.defensenews.com/unmanned/2021/11/05/darpa-nabs-gremlin-drone-in-midair-for-first-time/.
97 “Gremlins,” DARPA, at https://www.darpa.mil/program/gremlins.
98 For a discussion of various concepts of autonomy, see Paul Scharre and Michael C. Horowitz, An Introduction to
Autonomy in Weapon Systems, Center for a New American Security, February 13, 2015, at https://s3.us-east1.amazonaws.com/files.cnas.org/documents/Ethical-Autonomy-Working-Paper_021015_v02.pdf?mtime=
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the loop,” autonomous weapon systems, in which operators have the ability to monitor and halt a
weapon’s target engagement.99
LAWS would likely require computer algorithms and sensor suites to classify an object as hostile,
make an engagement decision, and guide a weapon to the target. Although these systems are not
yet in widespread development,100 they could enable military combat operations in
communications-degraded or -denied environments in which traditional systems are unable to
operate.
Potential Issues for Congress101
As Congress considers the future roles of UAS, it may examine a range of issues, including lethal
autonomous weapons and arms control, cost comparisons of future UAS with crewed aircraft,
personnel and skills implications, concepts of operation and employment, and the proliferation of
uncrewed technologies. The following sections provide a framework for Congress to analyze
programs in its role for authorizing and appropriating funding, and to enable Congressional
oversight of UAS programs.
Lethal Autonomous Weapons102
Approximately 30 countries and 165 nongovernmental organizations have called for a preemptive
ban on lethal autonomous weapons to address ethical concerns, such as a perceived lack of
accountability for the use of such weapons and a perceived inability to comply with the law of
armed conflict’s proportionality and distinction requirements.103 In addition, some analysts have
raised concerns about the potential operational risks posed by lethal autonomous weapons.104
These risks could arise from “hacking, enemy behavioral manipulation, unexpected interactions
with the environment, or simple malfunctions or software errors.”105 All automated systems may
20160906082257&focal=none.
99 Another category is semi-autonomous, or “human in the loop,” weapon systems that “only engage individual targets
or specific target groups that have been selected by a human operator.” Department of Defense Directive 3000.09,
“Autonomy in Weapon Systems,” updated May 8, 2017, at https://www.esd.whs.mil/portals/54/documents/dd/
issuances/dodd/300009p.pdf. See also Paul Scharre and Michael C. Horowitz, An Introduction to Autonomy in Weapon
Systems, Center for a New American Security, February 13, 2015, at https://s3.us-east-1.amazonaws.com/files.cnas.org/
documents/Ethical-Autonomy-Working-Paper_021015_v02.pdf?mtime=20160906082257&focal=none.
100 Some analysts have argued that certain loitering munitions such as the Israeli Harpy meet the United States’
definition of LAWS. See, for example, Defense Innovation Board, AI Principles: Recommendations on the Ethical Use
of Artificial Intelligence by the Department of Defense - Supporting Document, October 2019, p. 12, at
https://media.defense.gov/2019/Oct/31/2002204459/-1/-1/0/
DIB_AI_PRINCIPLES_SUPPORTING_DOCUMENT.PDF. In addition, although a United Nations report concluded
that Turkey’s deployment of the STM Kargu-2 constitutes the first use of a lethal autonomous weapon system in
combat, the U.N. described the Kargu-2 as being “programmed to attack targets” [emphasis added]. For this reason, it
is unlikely that the Kargu-2 meets the U.S. definition of LAWS. United Nations Security Council, “Letter dated 8
March 2021 from the Panel of Experts on Libya established pursuant to resolution 1973 (2011) addressed to the
President of the Security Council,” March 8, 2021, p. 17, at https://undocs.org/S/2021/229.
101 This section was written by John R. Hoehn, Analyst in Military Capabilities and Programs, unless otherwise noted.
102 This subsection was written by Kelley M. Sayler, Analyst in Advanced Technology and Global Security.
103 See CRS In Focus IF11294, International Discussions Concerning Lethal Autonomous Weapon Systems, by Kelley
M. Sayler.
104 See, for example, Paul Scharre, “Autonomous Weapons and Operational Risk,” Center for a New American
Security, February 2016, at https://www.cnas.org/publications/reports/autonomous-weapons-and-operational-risk.
105 Ibid.
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be vulnerable to such risks; however, such risks could be greater in LAWS because the human
operating the system would likely be unable to terminate engagements—potentially resulting in
wider-scale or more numerous instances of fratricide, civilian casualties, or other unintended
consequences.106 Some analysts have raised additional concerns that LAWS could be combined
with swarm technology to produce weapons of mass destruction.107 For example, analyst Zachary
Kallenborn has argued that such systems could be used to inflict casualties on infantry units or
massed civilians, or as genocidal weapons targeting particular ethnic groups.108 In the latter use
case, operators could potentially pair LAWS with biometric databases to enable the systems to
target particular individuals or particular groups of people.109 LAWS could be used similarly to
improve dispersal mechanisms for chemical, biological, radiological, or nuclear agents.110
Those analysts supporting a preemptive ban on LAWS have—in addition to the law of armed
conflict—appealed to the Martens Clause, which appears in the 1899 Hague Convention
preamble and states that weapons use should conform to the “principles of humanity and the
dictates of the public conscience.”111 They argue that LAWS contravene that requirement;
however, other analysts have noted that using the Martens Clause to ban a weapons system would
be unprecedented, and furthermore, that the legal status of the Martens Clause is questionable and
instead constitutes “merely a recognition of ‘customary international law.’”112
Other analysts and a number of national governments113—including the U.S. government114—
oppose a preemptive ban on LAWS.115 These parties have noted the potential humanitarian
benefits of such weapons, which may be able to “strike military objectives more accurately and
with less risk of collateral damage or civilian casualties” than traditional systems.116 Opponents of
a ban further contend that human operators will remain accountable for systems’ deployment and
106 Ibid.
107 Zachary Kallenborn, Are Drone Swarms Weapons of Mass Destruction?, United States Air Force Center for
Strategic Deterrence Studies, May 6, 2020, at https://media.defense.gov/2020/Jun/29/2002331131/-1/-1/0/
60DRONESWARMS-MONOGRAPH.PDF.
108 Ibid., p. 20.
109 For additional information on biometric technologies and how they might be integrated into LAWS, see CRS In
Focus IF11783, Biometric Technologies and Global Security, by Kelley M. Sayler.
110 Zachary Kallenborn and Phillip C. Bleek, “Swarming destruction: drone swarms and chemical, biological,
radiological, and nuclear weapons,” The Nonproliferation Review, vol. 25, January 2, 2019, at
https://www.tandfonline.com/doi/full/10.1080/10736700.2018.1546902.
111 Bonnie Docherty, Heed the Call: A Moral and Legal Imperative to Ban Killer Robots, Human Rights Watch,
August 21, 2018, at https://www.hrw.org/report/2018/08/21/heed-call/moral-and-legal-imperative-ban-killer-robots#.
112 Paul Scharre, Army of None: Autonomous Weapons and the Future of War (New York: W.W. Norton & Company,
2018).
113 For a discussion of specific country positions on LAWS, see CRS In Focus IF11294, International Discussions
Concerning Lethal Autonomous Weapon Systems, by Kelley M. Sayler.
114 In this instance, the position of the U.S. delegation to the United Nations Convention on Certain Conventional
Weapons (UN CCW)—the primary forum for international discussions of LAWS—is characterized as “the U.S.
government” position. The U.S. delegation to the UN CCW includes representatives of the Departments of State and
Defense and is authorized to engage in UN CCW discussions on behalf of the U.S. government.
115 If this position were to change, and the executive branch were to instead pursue an international treaty on LAWS,
then the Senate would be called upon to provide advice and consent.
116 See, for example, U.S. Government, “Humanitarian Benefits of Emerging Technologies in the Area of Lethal
Autonomous Weapons,” March 28, 2018, at https://ogc.osd.mil/Portals/99/Law%20of%20War/
Practice%20Documents/US%20Working%20Paper%20%20Humanitarian%20benefits%20of%20emerging%20technologies%20in%20the%20area%20of%20LAWS%20%20CCW_GGE.1_2018_WP.4_E.pdf?ver=O0lg6BIxsFt57nrOuz3xHA%3D%3D.
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for ensuring that the systems’ use complies with international humanitarian law.117 Finally, some
argue that a preemptive ban on LAWS could inhibit research into technologies that may provide
civilian benefits (e.g., eldercare robots).118
As it conducts oversight, Congress may seek additional information about LAWS, to include
holding congressional hearings or requiring DOD to report certain information related to
LAWS—such as U.S. decisions to develop or field LAWS, DOD efforts to mitigate the
operational risks posed by LAWS, or threats posed by adversaries’ development of LAWS—to
the relevant congressional committees.119 Congress may also seek to conduct oversight of the use
of certain enabling technologies for LAWS, such as artificial intelligence or biometric
technologies. For example, Congress could require DOD to brief the relevant congressional
committees on the department’s efforts to ensure that data training sets have been ethically
collected and sufficiently tested for bias.120
Cost of Future UAS Compared with Crewed Systems
The net cost of UAS, relative to crewed aircraft, depends on several factors, and Congress may
consider the potential cost of uncrewed aircraft compared with crewed counterparts. Although the
development costs of some uncrewed aircraft may be high because they require leveraging
relatively immature technologies (as was the case with the RQ-4 Global Hawk),121 the operations
and sustainment costs of uncrewed aircraft may likely be lower than crewed aircraft.122 As a
result, comparing similar numbers of aircraft and their capabilities, uncrewed aircraft may cost
less over their lifecycle than a comparable crewed platform. As a result, while uncrewed aircraft
may have a larger operations and maintenance cost overall when compared to crewed aircraft, the
flying hour cost per aircraft may be lower (i.e., uncrewed aircraft may be flying more as a result
of lower costs to operate per hour). For example, when comparing costs for close air support
aircraft, DOD states the reimbursement rate (the cost per hour to “rent” an aircraft from DOD) for
an MQ-9 is $652 per hour for DOD users, while an A-10C costs $8,130 per hour.123
117 See, for example, U.S. Government, “Human-Machine Interaction in the Development, Deployment and Use of
Emerging Technologies in the Area of Lethal Autonomous Weapons Systems,” August 28, 2018, https://docslibrary.unoda.org/Convention_on_Certain_Conventional_Weapons__Group_of_Governmental_Experts_(2018)/2018_GGE%2BLAWS_August_Working%2BPaper_US.pdf.
118 See, for example, Government of Japan, “Possible outcome of 2019 Group of Governmental Experts and future
actions of international community on Lethal Autonomous Weapons Systems,” March 22, 2019, at https://docslibrary.unoda.org/Convention_on_Certain_Conventional_Weapons__Group_of_Governmental_Experts_(2019)/CCW_%2BGGE%2B.1_%2B2019_%2BWP3%2BJAPAN.pdf.
119 See, for example, Section 247 of the FY2019 NDAA (P.L. 115-232).
120 See, for example, Section 5708 of the FY2020 NDAA (P.L. 116-92). For additional information about AI and
algorithmic bias, see CRS Report R45178, Artificial Intelligence and National Security, by Kelley M. Sayler.
121 For example, see Department of Defense, Selected Acquisition Report (SAR), RQ-4 Global Hawk, DDA&T(Q&A)823-252, Washington, DC, December 31, 2010, p. 4, at https://nation.time.com/wp-content/uploads/sites/8/
2012/03/dod-gh-2010-sar.pdf.
122 Congressional Budget Office, Usage Patterns and Costs of Unmanned Aerial Systems, 57090, Washington, DC,
June 1, 2021, at https://www.cbo.gov/system/files/2021-06/57090-UAS.pdf.
123 This analysis assumes that aircraft performing close air support would be supporting a DOD user. The Office of the
Secretary of Defense Comptroller does denote different hourly reimbursement rates for other federal users, Foreign
Military Sales Users, and others in its annual reimbursement rate calculations. See Letter from Office of the Secretary
of Defense Comptroller for Program/Budget, “Memorandum for Fiscal Year (FY) 2022 Department of Defense (DOD)
Fixed Wing and Helicopter Reimbursement Rates,” October 1, 2021, at https://comptroller.defense.gov/Portals/45/
documents/rates/fy2022/2022_b_c.pdf.
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In addition, smaller uncrewed aircraft used for intelligence, surveillance, and reconnaissance
missions could be equipped with less expensive, less capable sensors than those installed in
crewed aircraft, while increasing the number of sensors providing information. At an individual
level, this arrangement might result in uncrewed aircraft that are less capable than crewed
aircraft; however, the cost benefit may enable the sensors to be aggregated, providing a more
detailed and responsive picture of the battle space. The Air Force, in particular, argues that lower
cost uncrewed aircraft could potentially help mitigate crewed and uncrewed aircraft inventory
shortfalls,124 which is a continual congressional concern.125
In evaluating emerging UAS programs, through its authorization and oversight functions,
Congress has several potential options to explore this issue. First, Congress may consider passing
legislation seeking additional information on the impact of UAS on DOD’s aircraft force
structure. For example, the FY2015 National Defense Authorization Act (NDAA) required the
Comptroller General to conduct a study to evaluate Air Force close air support alternatives.126
Congress has also historically required DOD to provide a 30-year aircraft plan, which has not
been delivered to Congress publicly since 2018.127
Personnel Implications
UAS may require an equal or greater number of military personnel than their crewed
counterparts. For example, although MQ-9 UAS are uncrewed, the Air Force currently requires
49 personnel in a mission command element and 59 personnel forward deployed to launch,
recover, and maintain four aircraft (a total requirement of 108 personnel for four MQ-9 UAS, or
27 personnel per aircraft).128 The Air Force requires 61 personnel (or 56% of the total requirement
for four aircraft) to perform maintenance for these aircraft. It is unclear what the personnel
requirements are for more sophisticated UAS like the RQ-170.129
The total number of personnel required to operate UAS may increase in the future, along with a
different ratio of skills required to operate those systems. For example, although most current
uncrewed aircraft are nonstealthy turboprop aircraft, future uncrewed aircraft with stealth features
and/or turbojet propulsion would likely have different maintenance requirements to maintain the
engine along with ensuring stealth coatings are in sufficient condition. Although future UAS may
need fewer pilots, weapons systems officers, and navigators, DOD may require additional
intelligence and command-and-control personnel to process increased data and manage uncrewed
assets (particularly with the implementation of manned-unmanned teaming).
Congress, through its authorization and oversight functions, has several options regarding this
potential issue. First, Congress may consider potentially passing legislation seeking a report
124 Abraham Mahshie, “Kendall: Air Force Has an ‘Affordability Problem’ As It Tries to Meet Capability Gap,” Air
Force Magazine, June 1, 2022, at https://www.airforcemag.com/kendall-air-force-has-an-affordability-problem-as-ittries-to-meet-capability-gap/.
125 For example see P.L. 116-92§143.
126 P.L. 113-291 §132.
127 10 USC §231a. For more information see CRS In Focus IF10999, Defense’s 30-Year Aircraft Plan Reveals New
Details, by Jeremiah Gertler.
128 Todd Harrison, Rethinking the Role of Remotely Crewed Systems in the Future Force, Center For Strategic and
International Studies, Washington, DC, March 3, 2021, at https://www.csis.org/analysis/rethinking-role-remotelycrewed-systems-future-force#:~:text=A%20typical%20MQ%2D1%20or,as%20shown%20in%20Table%201.
129 For more information on the RQ-170 see CRS Report R47067, Unmanned Aircraft Systems: Current and Potential
Programs, by John R. Hoehn and Paul K. Kerr.
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comparing personnel requirements between crewed aircraft and UAS from DOD. For example,
section 165 of the FY2021 NDAA required DOD to create a roadmap explaining “the anticipated
mix of manned and unmanned aircraft, number of platforms, and associated aircrew and
maintainers for support of United States Special Operations Forces.”130 Second, the Armed
Services committees may consider authoring report language accompanying the NDAA to seek
additional information on this issue. For example, the Senate Armed Services Committee report
accompanying the FY2020 NDAA requested the Army to provide a briefing to the defense
committees to outline its requirements for UAS pilots and maintainers.131 Third, the Armed
Services Committees may consider a committee hearing to consider testimony from experts in the
field. For example, the House Armed Services Committee held a hearing on March 29, 2017, to
receive testimony from DOD experts on the military’s pilot shortage problem.132
Proliferation of Uncrewed Technologies
More than 95 countries reportedly operated some sort of uncrewed military aircraft in 2021,
compared with 60 countries in 2010.133 Historically, the United States has produced the most
sophisticated UAS (e.g., the MQ-1 Predator, the RQ-4 Global Hawk, and the RQ-170 Sentinel),
including UAS with advanced sensors and/or stealth features.134 However, in recent years, Iran,
Israel, China, and Turkey have demonstrated increasing levels of sophistication in their
approaches to uncrewed technologies, with Iranian, Turkish, and Chinese UAS featuring
prominently in recent military operations. For example, Iran demonstrated its ability to launch
sophisticated attacks with uncrewed aircraft in September 2019, when Houthi rebels in Yemen—
using Iranian supplied aircraft and missiles—attacked two Saudi oil refineries.135 Iran has also
reportedly exported uncrewed aircraft to Hamas and rebel forces in Syria.136 The Turkishdeveloped Baykar Bayraktar TB2 was used in military operations during the conflict between
Armenia and Azerbaijan in 2020, and has been used in Ukraine in 2022.137 Similarly, Libyan
forces are reported to have used both Turkish and Chinese systems.138 According to one press
130 P.L. 116-283 §165.
131 U.S. Congress, Senate Committee on Armed Services, National Defense Authorization Act for Fiscal Year 2020,
116th Cong., 1st sess., June 11, 2019, S. Rept, 116-48 (Washington: GPO, 2019), p. 56.
132 U.S. Congress, House Committee on Armed Services, Subcommittee on Military Personnel, Military Pilot Shortage,
115th Cong., 1st sess., March 29, 2017, 25-095 PDF (Washington: GPO, 2017), at https://www.govinfo.gov/content/
pkg/CHRG-115hhrg25095/html/CHRG-115hhrg25095.htm.
133 Ibid.
134 Ibid.
135 Ben Hubbard, Palko Karasz, and Stanley Reed, “Two Major Saudi Oil Installations Hit by Drone Strike, and U.S.
Blames Iran,” New York Times, September 14, 2019, at https://www.nytimes.com/2019/09/14/world/middleeast/saudiarabia-refineries-drone-attack.html.
136 Seth J. Franztman, Iran’s drones are clones. Now they’re being used in multiple conflicts., The Atlantic Council,
Washington, DC, November 18, 2021,at https://www.atlanticcouncil.org/blogs/iransource/irans-drones-are-clonesnow-theyre-being-used-in-multiple-conflicts/.
137 Jack Destsch, “The U.S. Army Goes to School on Nagorno-Karabakh Conflict,” Foreign Policy, March 30, 2021, at
https://foreignpolicy.com/2021/03/30/army-pentagon-nagorno-karabakh-drones/. Derek Gatopoulos and Suzan Fraser,
“Cheap but lethal Turkish drones bolster Ukraine’s defenses,” Associated Press, March 17, 2022, at
https://apnews.com/article/russia-ukraine-middle-east-africa-libya-europe-ecb9e820ea4bddb4464d7e8cb40e82fc.
138 In particular, the Washington Post reported that Chinese-developed uncrewed aircraft offered a cheaper alternative
with similar capabilities to the U.S.-developed MQ-9 Reaper. Sudarsan Raghavan, “In Libya, cheap, powerful drones
kill civilians and increasingly fuel the war,” Washington Post, December 22, 2019, at
https://www.washingtonpost.com/world/middle_east/libyas-conflict-increasingly-fought-by-cheap-powerful-drones/
2019/12/21/a344b02c-14ea-11ea-bf81-ebe89f477d1e_story.html.
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report, Chinese-developed uncrewed aircraft were cheaper than the U.S.-developed MQ-9 Reaper
and had similar capabilities.139 The continued proliferation of these systems could influence the
future of U.S. export policy and the ability of the United States to control access to advanced
UAS technologies. Export controls of military UAS are governed by multilateral export controls,
namely the Missile Technology Control Regime (MTCR), along with national export controls
managed by the State Department.140 Both the Biden Administration and the previous Obama and
Trump Administrations have proposed changes to these export controls to make U.S.
manufacturers more competitive in the international UAS market.141 Congress, as part of its
constitutional authority to provide advice and consent on treaties, as well as in its oversight
function, may consider potential changes to MCTR and other treaties.
139 Sudarsan Raghavan, “In Libya, cheap, powerful drones kill civilians and increasingly fuel the war,” Washington
Post, December 22, 2019, at https://www.washingtonpost.com/world/middle_east/libyas-conflict-increasingly-foughtby-cheap-powerful-drones/2019/12/21/a344b02c-14ea-11ea-bf81-ebe89f477d1e_story.html.
140 CRS Report R47067, Unmanned Aircraft Systems: Current and Potential Programs, by John R. Hoehn and Paul K.
Kerr.
141 For more information see CRS In Focus IF11069, U.S.-Proposed Missile Technology Control Regime Changes, by
Paul K. Kerr.
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Appendix. Intelligence Support of UAS Targeting in
Counterterrorism Operations142
Intelligence support for UAS counterterrorism operations has inherent limitations. U.S.
government research and development programs are meant to address some of these limitations.
For example, the United States Army and the Intelligence Advanced Projects Research Agency
(IARPA) have been pursuing technologies to improve aircraft endurance and enhance image
quality, with the goals of longer dwell time over target areas and clearer, more stable UAS video
and imagery.143 In the meantime, the limitations of UAS platforms have significant political and
ethical implications, particularly regarding efforts to minimize the distance to target areas and to
reduce the risk of human error in interpreting imagery. From an ethical perspective, a limited
intelligence capability in a target area increases the risk of errors in interpreting imagery for
targeting. In areas like Afghanistan, the already challenging task of intelligence support to timesensitive targeting becomes more difficult in tactical situations where intelligence sources and
infrastructure, as well as local intelligence partnerships, are limited.
Basing access is an important political consideration because UAS basing may have to be
negotiated with countries in close proximity to a target area, or may require long transit times that
limit the extent to which a UAS can observe an area. Presently, the United States has in
Afghanistan neither an extensive organic intelligence capability, nor the strong international
partnerships that it had in the past. According to the Commander of Central Command, General
Kenneth McKenzie, “As we go forward in our ability to create what we call the ecosystem that
allows you to see what is going on the ground and put all that together, it is going to get a lot
harder to do that, particularly in places like Afghanistan.”144
The August 2021 U.S. military withdrawal from Afghanistan raises questions about how
effectively the intelligence community can support counterterrorist operations from “over the
horizon,” meaning over a landlocked country where intelligence coverage is limited.145 U.S.
officials have reportedly acknowledged that the withdrawal from Afghanistan has resulted in the
loss there of 90% of UAS intelligence collection capabilities.146 Moreover, regardless of
proximity to a target area or anticipated advances in UAS technology, intelligence support of
counterterrorism operations will continue to depend on a human interface: analysts responsible
for interpreting video and still images and integrating other possible sources, such as tactical
human and signals intelligence.
142 This section was written by Michael E. Devine, Analyst in Intelligence and National Security.
143 See U.S. Army SBIR/STTR, Unmanned Aircraft System (UAS) Full Motion Video (FMV) Enhancement, at
https://www.armysbir.army.mil/topics/unmanned-aircraft-system-uas-full-motion-video-fmv-enhancement/. See also
Robert K. Ackerman, “IARPA Strives for Innovative Portable Power Sources,” Signal Magazine, AFCEA, October 7,
2021, at https://www.afcea.org/content/iarpa-strives-innovative-portable-power-sources.
144 Testimony of General Kenneth McKenzie, Hearing to Receive Testimony on the Conclusion of Military Operations
in Afghanistan and Plans for Future Counterterrorism Operations, United States Senate Armed Services Committee,
September 28, 2021, at https://www.armed-services.senate.gov/imo/media/doc/21-73_09-28-2021.pdf.
145 See, for example, Michael Hirsh, “U.S. Military Concedes It’s Unready to Fight Terrorism from ‘Over the
Horizon’” Foreign Policy, September 30, 2021, at https://foreignpolicy.com/2021/09/30/over-the-horizoncounterterrorism-afghanistan-united-states-flying-blind/.
146 Warren P. Strobel, Gordon Lubold, and Michael R. Gordon, “U.S. Pledge to Fight Terrorists in Afghanistan will be
Harder without Boots on the Ground,” Wall Street Journal, August 31, 2021, at https://www.wsj.com/articles/u-s-spledge-to-fight-terrorists-in-afghanistan-will-be-harder-without-boots-on-the-ground-11630402200.
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An August 29, 2021, MQ-9 Reaper UAS strike in Kabul that killed at least 10 Afghans—
including 7 children—which was incorrectly interpreted by analysts as targeting an imminent
terrorist threat, underscores the difficulty of targeting in such an environment.147 General
McKenzie acknowledged challenges in acquiring actionable intelligence in this situation: “We did
not have the luxury of developing pattern of life.”148 An investigation by the Inspector General of
the Air Force, Lieutenant General Sami Said, concluded that “confirmation bias and
communication breakdowns” were factors in analysts incorrectly interpreting UAS surveillance
video.149
When limited to airborne sensors, “developing a pattern of life” entails increasing the UAS dwell
time over a potential target—more easily achieved in a permissive environment, or by having
greater proximity to the target area than the United States currently has in Afghanistan. According
to media reporting, to date the United States has been unsuccessful in negotiating the use of bases
in neighboring countries for UAS operations over Afghanistan, although Pakistan is continuing to
permit overflights of its territory.150 A significant concern for Pakistan in particular is the political
cost of allowing base access, which is strongly opposed by the general public.151 Obstacles to
establishing and maintaining a layered intelligence architecture in the region to support reliable
UAS counterterrorist operations comes at a time when, according to Chairman of the Joint Chiefs
of Staff, General Mark A. Milley, a reconstituted Al Qaeda “with aspirations to attack the United
147 Matthieu Aikins, Christoph Koettl, Evan Hill, and Eric Schmitt, “Times Investigation: U.S. Drone Strike Suggests
No ISIS Bomb,” New York Times, September 10, 2021 (updated October 16, 2021), at https://www.nytimes.com/2021/
09/10/world/asia/us-air-strike-drone-kabul-afghanistan-isis.html. Defense officials later admitted that the suspected
terrorist was, in fact, Zemari Ahmadi, an aid worker who had no affiliation with the Islamic State and who, at the time
of the strike, was transporting colleagues to and from work, and loading canisters of water onto his truck to bring to his
family. DOD officials admitted to making a “tragic mistake,” and Secretary of Defense Lloyd Austin ordered an
investigation to determine “the degree to which strike authorities, procedures, and processes need to be altered in the
future.” The United States’ inability to benefit from strong international partnerships on the ground is compounded by
indications, reported in the media, of small numbers of personnel formerly with Afghanistan’s intelligence service, the
National Directorate of Security (NDS), supporting the Islamic State-Khorasan Province. See Yaroslav Trofimov, “Left
Behind after U.S. Withdrawal, Some Former Afghan Spies and Soldiers Turn to Islamic State,” Wall Street Journal,
October 31, 2021, at https://www.wsj.com/articles/left-behind-after-u-s-withdrawal-some-former-afghan-spies-andsoldiers-turn-to-islamic-state-11635691605. This article also reported that the United States was providing some
intelligence on Islamic State-Khorasan to the Taliban government.
148 Ibid.
149 U.S. Department of Defense Transcript: “Pentagon Press Secretary John F. Kirby and Air Force Lt. Gen. Sami D.
Said Hold a Press Briefing,” November 3, 2021, at https://www.defense.gov/News/Transcripts/Transcript/Article/
2832634/pentagon-press-secretary-john-f-kirby-and-air-force-lt-gen-sami-d-said-hold-a-p/. In the press briefing, Lt.
Gen. Said described confirmation bias as a condition in which someone (such as an analyst) consciously or
subconsciously interprets a situation or an image in a certain way, and views all subsequent information related to it
through the same lens. It has also been defined as a phenomenon that is the “result of an over-reliance on one source of
intelligence at the expense of integrating multiple channels of information.” See Sarah Kreps and Paul Lushenko, “US
Faces Immense Obstacles to Continued Drone War in Afghanistan,” TechStream, Washington DC: Brookings, October
19, 2021, at https://www.brookings.edu/techstream/us-faces-immense-obstacles-to-continued-drone-war-inafghanistan/. See also Alex Horton, Dan Lamothe, and Karoun Demirjian, “Botched Drone Strike that Killed 10
Civilians in Kabul was not a Result of Criminal Negligence, Pentagon Says,” The Washington Post, November 3, 2021,
at https://www.washingtonpost.com/national-security/2021/11/03/kabul-drone-strike-inspector-general-report/.
150 Mark Mazzetti and Julian E. Barnes, “C.I.A. Scrambles for New Approach in Afghanistan,” New York Times, June
6, 2021, updated August 27, 2021, at https://www.nytimes.com/2021/06/06/us/politics/cia-afghanistan-pakistan.html.
See also Michael Hirsh, “U.S. Military Concedes.”
151 Ibid. Pakistan’s foreign minister, Shah Mehmood Qurshi, reportedly declared in July 2021, “I want to tell Pakistanis
that no U.S. base will be allowed by Prime Minister Imran Khan so long as he is in power.” The United States had used
Shamsi airbase in Pakistan for UAS operations targeting Al Qaeda until being told to leave in 2011 following the U.S.
raid on Osama bin Ladin’s Pakistan compound and an incident in which a NATO strike mistakenly killed dozens of
Pakistani soldiers along the border with Afghanistan.
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Unmanned Aircraft Systems: Roles, Missions, and Future Concepts
States is a very real possibility” in the next 12 to 36 months.152 For the time being, the closest
base for prospective UAS operations over Afghanistan is Al Udeid Airbase, Qatar, which requires
significant aircraft fuel consumption in transit over the Persian Gulf and Pakistan, and
consequently limits the amount of time that can be spent observing the target area.153
Author Information
John R. Hoehn, Coordinator
Analyst in Military Capabilities and Programs
Michael E. DeVine
Analyst in Intelligence and National Security
Kelley M. Sayler
Analyst in Advanced Technology and Global
Security
Acknowledgments
The authors are indebted to Jeremiah “JJ” Gertler, former CRS Specialist in Military Aviation, for his
contributions to this report.
Disclaimer
This document was prepared by the Congressional Research Service (CRS). CRS serves as nonpartisan
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152 Statement of General Mark A. Milley, Hearing to Receive Testimony on the Conclusion of Military Operations in
Afghanistan and Plans for Future Counterterrorism Operations, United States Senate Armed Services Committee,
September 28, 2021, at https://www.armed-services.senate.gov/imo/media/doc/21-73_09-28-2021.pdf.
153 Sarah Kreps and Paul Lushenko, “US Faces Immense Obstacles to Continued Drone War in Afghanistan,”
TechStream, Washington, DC: Brookings, October 19, 2021, at https://www.brookings.edu/techstream/us-facesimmense-obstacles-to-continued-drone-war-in-afghanistan/.
Congressional Research Service
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