The Open Skies Treaty: Observation Overflights of Military Activities

Congressional research reportSep 11, 2000

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The Open Skies Treaty:

Observation Overflights of Military Activities

September 11, 2000

Amy Woolf

Specialist in National Defense

Foreign Affairs, Defense, and Trade Division

Congressional Research Service ˜ The Library of Congress

The Open Skies Treaty:

Observation Overflights of Military Activities

Summary

On March 24, 1992, the United States, Canada, and 22 European nations signed

the Treaty on Open Skies. The United States officially ratified the treaty on

November 3, 1993. The treaty has not yet entered into force, however, because

Russia and Belarus have not yet ratified it.

President Bush revived the Open Skies concept in May 1989. At the time, the

United States believed that the Open Skies concept would reduce the chances of

military confrontation and build confidence in Europe by providing participants with

the ability to collect information about the military forces and activities of others in

the treaty. In addition, even though the United States and Russia can collect this type

of information with sophisticated observation satellites, Open Skies observation flights

will provide nations who do not have their own satellites with a way to participate in

the data collection and confidence-building process.

The parties to the Treaty on Open Skies have agreed to permit unarmed aircraft

to conduct observation flights over their entire territories. The United States Air

Force has modified three C-135 aircraft for this purpose. Open Skies aircraft can be

equipped with four types of sensors: optical panoramic and framing cameras; video

cameras; infrared line-scanning devices; and sideways-looking synthetic aperture

radars. These sensors must be based on off-the-shelf technology that is available to

all participants in the treaty. The treaty includes quotas that specify maximum

numbers of observation flights that can occur within each nation each year and the

maximum number of observation flights each nation can conduct each year. For the

United States, these quotas are 42 flights per year; however, only 4 flights will occur

over U.S. territory in the first year that the treaty is in force. In addition, the United

States will conduct only 9 observation flights during the first year of treaty

implementation; 8 over Russia and Belarus and one, in conjunction with Canada, over

Ukraine.

When the Senate reviewed the Open Skies Treaty in 1992 and 1993, Members

raised several concerns about the implications of the treaty for the United States. For

example, some were concerned that the costs of outfitting and operating the U.S.

Open Skies aircraft would outweigh the benefits that the United States would receive

by participating in the treaty. As a result, the Senate suggested that the United States

restrict its participation, conducting fewer than the 42 permitted observation flights

per year. Some were also concerned about potential risks to U.S. security from

observation flights that would gather information on U.S. military forces and

activities. If the Open Skies Treaty remains in force for many years, the United States

could host dozens of visits by other participants, with foreign military aircraft

equipped with sensors flying over U.S. territory. Virtually all observers agree,

however, that these flights will pose no security threat to the United States.

Contents

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Key Provisions of the Treaty on Open Skies . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Provisions Governing Observation Flights . . . . . . . . . . . . . . . . . . . . . . . . . 4

Territorial Coverage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Flight Distances and Airfields . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Time Lines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Mission Plans . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Annual Quotas for Observation Flights . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Determining Passive and Active Quotas . . . . . . . . . . . . . . . . . . . . . . . 7

Allocation of Observation Flights Among the Parties . . . . . . . . . . . . . 7

Passive and Active Quotas for the United States . . . . . . . . . . . . . . . . . 8

Permitted Aircraft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

U.S. Aircraft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Permitted Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Sensor Quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Treaty Participation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Current Status and Implementation Plans . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Status of Treaty Ratification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

U.S. Ratification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Ratification by Other Parties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Planning for Implementation in the U.S. . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Interagency Participation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Open Skies Aircraft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Trial and Training Flights . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Implications for the United States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Value of Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Security Concerns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

List of Tables

Table 1. Parties to the Treaty on Open Skies . . . . . . . . . . . . . . . . . . . . . . . . . . 17

The Open Skies Treaty:

Observation Overflights of Military Activities

Introduction

On March 24, 1992, the United States, Canada, and 22 European nations signed

the Treaty on Open Skies.1 This Treaty had grown out of a May 1989 proposal by

President George Bush; he envisioned an agreement that would promote cooperation

and build confidence between the two Cold War blocs — NATO and the Warsaw

Pact. But the Warsaw Pact dissolved before the Treaty was completed, so it emerged

as an agreement among European nations, the United States and Canada (rather than

as a treaty between two opposing alliances). The Open Skies Treaty has not yet

entered into force, however, because Russia and Belarus have not ratified it.

Each of the parties to the Treaty on Open Skies will permit unarmed aircraft

operated by any other party to fly over its territory to observe military forces and

activities. By allowing the participants to gain insights and understanding into the

military capabilities of potential adversaries, the treaty can, according to its

supporters, build confidence, reduce the chances of military confrontation, and

encourage cooperation among the nations of Europe. Under the terms of the Treaty,

observation aircraft from the other participants can conduct up to 42 flights over U.S.

territory each year. (Russia, too, will be subject to 42 flights; the other participants

will host between 2 and 12 flights each year.) Consequently, if the Open Skies Treaty

remains in force for many years, the United States could host dozens of visits by other

participants. Virtually all observers agree that these flights will pose no security threat

to the United States. However, questions about the presence of foreign military

aircraft and the purpose of the observation flights may come up when the observation

flights occur.

This report provides basic information about the rationale for the Open Skies

Treaty, the provisions that govern its implementation, and the capabilities of the

aircraft and sensors that will be used during the observation flights. This information

can help Congress review the implementation of the treaty; it may also help Members

respond to concerns that constituents may raise about the presence of Open Skies

aircraft and observation flights around the country. The first section of this report

briefly reviews the history of negotiations on Open Skies. The second discusses key

provisions of the 1992 treaty. The third reviews the current status of the treaty and

its implementation.

The parties to the treaty are listed in the Table at the end of the report. The Text of the

Treaty can be found in U.S. Congress, Senate, Treaty on Open Skies, Message from the

President of the United States, Treaty Doc. 102-37, Washington, 1992.

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Background

The idea for a treaty on Open Skies first appeared in 1955, when President

Eisenhower suggested that the United States and Soviet Union permit aerial

observation flights over each other’s territories. In principle, aerial observation flights

would permit the two nations to reduce their reliance on worst-case estimates of the

other side’s military capabilities and to demonstrate that they were willing to

cooperate with each other to ease tensions. At the same time, in the era before the

development of observation satellites, aerial observation flights were only way for the

United States to gain needed intelligence information about military forces and

activities inside the Soviet Union. According to the Bush Administration, the

Eisenhower proposal “would have dramatically changed the quantity and quality of

our knowledge of the Soviet Union.”2 The Soviet leadership rejected President

Eisenhower’s proposal, arguing that the observation flights would simply legalize

espionage.

President Bush revived the Open Skies concept in May 1989. At the time, as the

Cold War was ending, the United States believed increased transparency in Europe

would reduce the chances of military confrontation and build confidence. According

to Secretary of State James Baker, Open Skies “would promote and consolidate the

international trends towards openness already in train.”3 The Bush Administration

also viewed Open Skies as a test of Soviet willingness to move forward in a

cooperative relationship with the United States. According to President Bush, “Such

unprecedented territorial access would show the world the true meaning of the

concept of openness. The very Soviet willingness to embrace such a concept would

reveal their commitment to change.”4

Unlike the bilateral 1955 version of Open Skies, the negotiations that began in

February 1990 included all of the members of NATO and the Warsaw Pact.5 The

United States sought a pact-to-pact treaty, with the United States and NATO

conducting observation flights over the Soviet Union and Warsaw Pact nations, and

vice versa. However, as the negotiations proceeded, it became evident that the

Eastern European nations were not only unwilling to rely on Soviet technology to

U.S. Congress. Senate. Committee on Foreign Relations. Treaty on Open Skies. Hearing,

102d Congress, 2nd Session. September 22, 1992. Washington, G.P.O., 1992. p. 40.

U.S. Congress. Senate. The Treaty on Open Skies. Message from the President of the

United States, 102d Congress, 2nd Session. Washington, G.P.O., 1992. p. viii.

Remarks at the Texas A&M University Commencement Ceremony in College Station,

Texas, May 12, 1989. Weekly Compilation of Presidential Documents, v. 25, May 22, 1989.

p. 702.

The United States won the support of its NATO allies in consultations that began in August

1989; Canada took a particularly active role in advancing the negotiations. See Tucker,

Jonathan B. Back to the Future: The Open Skies Talks. Arms Control Today, v. 20, October

1990. p. 21.

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collect data, but were also interested in conducting their observation flights over

Soviet territory.6

As a result, after the abortive Soviet coup in August 1991, the participants

altered their approach and produced a treaty among nations rather than a pact

between alliances. Each of the parties to the treaty can collect information about and

improve its understanding of the military forces and activities of any of the other

participants. As Secretary of State Baker indicated when the treaty was submitted to

the Senate, “The Treaty on Open Skies represents the widest-ranging international

effort to date to promote openness and transparency of military forces and activities.”7

But the treaty would do more than just build confidence and reduce the risk of

conflict. Many viewed the treaty as a symbol of the new Europe. According to

Thomas Graham, the acting Director of the Arms Control and Disarmament Agency,

“By strengthening the environment of security and confidence, such measures increase

the ability of our new partners in Europe to fill their commitments as participants in

the CSCE and to ensure that democratic change is irrevocable. They also facilitate

further security cooperation within a more stable and predictable international

environment.”8

Key Provisions of the Treaty on Open Skies

Objectives

The primary objective of the Open Skies Treaty is to reduce the risk of conflict

by providing participants with the ability to collect information about the military

forces and activities of others in the treaty. In particular, “information derived from

Open Skies flights can contribute to participating states’ national efforts to address

a range of military and civil issues. These could involve observing known military

facilities and large-scale force deployments, determining the presence — but not the

detailed composition — of major military forces or large, possibly military-related

construction activities. As such, Open Skies flights could contribute to recognizing

the scope of excess military preparedness or unusual military activity.”9 This

information can help a nation make informed assessments about the military

capabilities of its neighbors, provide early warning of threatening military activities or,

conversely, information that could dispel concerns about ongoing military activities.

See the prepared statement of Ambassador John Hawes in U.S. Congress. Senate.

Committee on Foreign Relations. Treaty on Open Skies. Report 103-5, 103d Congress, 1st

Session. Washington, G.P.O., 1993. p. 157.

U.S. Congress. Senate. Treaty on Open Skies. Message from the President of the United

States. p. vii.

U.S. Congress. Senate. Committee on Foreign Relations. Treaty on Open Skies. Report

103-5. p. 151.

U.S. Congress. Senate. Committee on Foreign Relations. Treaty on Open Skies. Hearing,

102d Congress, 2nd Session. September 22, 1992. Washington, G.P.O., 1992. p. 39.

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Most observers agree that the Open Skies Treaty will add little to U.S.

knowledge of Russian military forces and activities and little to Russian knowledge

of U.S. or NATO forces and activities. The United States and Russia each operate

sophisticated observation satellites that can provide information without any

cooperation from the other side.10 Nonetheless, many have noted that the observation

flights will provide nations who do not have their own satellite systems with a way to

participate in the data collection and confidence-building process. As Ambassador

John Hawes, the U.S. representative to the Conference on Open Skies, noted, “the

treaty offers each of the participating states, regardless of size or level of

technological development, the opportunity for direct involvement in the observation

of military forces and activities of concern on the territory of other participating

states. For most of the participating states ... Open Skies will provide the first

opportunity they have had to acquire this kind of hard information relevant to their

security.”11

Provisions Governing Observation Flights

Territorial Coverage. The parties to the Open Skies Treaty have agreed to

make all of their territory accessible to overflights by unarmed, fixed wing aircraft.

The only limitations on the flights would be those required for reasons of flight safety.

The United States and its NATO allies proposed unrestricted access for Open

Skies observation flights when the negotiations began. By the end of the first round

of negotiations in February 1990, the East European participants had agreed to this

proposal. The Soviet Union, on the other hand, sought to exclude large areas of its

territory from the observation flights for “national security reasons.” It also sought

to limit the duration of observation flights and to require that flights over some areas,

such as nuclear power plants and densely populated urban areas, occur at a minimum

altitude of 10,000 feet.12 When the negotiations resumed in November 1991 (after

the failed coup in Moscow), the Soviet Union announced that it would accept full

territorial coverage if flights over Soviet territory were conducted with Soviet aircraft

carrying Soviet sensors.13 This would allow Soviet officials to confirm that

observation aircraft were not carrying unauthorized sensors that could collect

sensitive information. Although the other participants preferred to use their own

aircraft in observation flights, they accepted this compromise.

Flight Distances and Airfields. According to the Treaty, to ensure that

observation flights cover the entire territory of participating nations, each party to the

In the arms control context, these satellites are known as “national technical means” of

verification (NTM).

U.S. Congress. Senate. Committee on Foreign Relations. Treaty on Open Skies. Hearing,

September 22, 1992. p. 4.

For a description of the opening negotiating positions on Open Skies, see Tucker, Jonathan

B. Back to the Future: The Open Skies Talks. Arms Control Today, v. 20, October 1990.

pp. 21-23.

See the prepared statement of Michael L. Moodie in U.S. Congress. Senate. Committee

on Foreign Relations. Treaty on Open Skies. Hearing, September 22, 1992. p. 9.

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Treaty must specify the location of airfields that observation flights can originate from

and the maximum distance that flights from these airfields can travel. Every part of

the participant’s territory must be accessible to a flight that originates from one of the

airfields and travels no more than the specified maximum distance.

The United States has designated Travis Air Force Base in California, Elmendorf

Air Force Base in Alaska, Dulles International Airport outside Washington D.C. and

Lincoln Municipal Airport in Nebraska as its Open Skies airfields. The maximum

distance for flights originating at Travis and Elmendorf Air Force bases are 4,000

kilometers (2,455 miles) and 3,000 kilometers (1,841 miles), respectively. The

maximum distance for flights originating at Dulles and Lincoln Municipal airports are

4,900 kilometers (3,007 miles) and 4,800 kilometers (2,946 miles), respectively.

Travis Air Force Base and Dulles International Airport will also serve as the Points

of Entry for Open Skies aircraft and crews that come to the United States for

inspections. All flights must land at these facilities first, even if they plan to conduct

their observation flights from other Open Skies Airfields.14

Time Lines. The Open Skies Treaty specifies that a nation seeking to conduct

an observation flight must inform the observed nation of its intentions 72 hours before

the observation team arrives at the Point of Entry (Dulles or Travis AFB, in the U.S.).

This notice is designed to ensure that the host country has enough time before the

observation begins to suspend any sensitive military exercises or activities that it

would not want observed during the flight. The observation flight can begin as soon

as 24 hours after the observation team arrives in the host country. Because the host

nation will not know precisely which areas will be covered by the observation flight

until the team arrives at the point of entry, it would not have enough time to conceal

large formations or concentrations of military forces in that area. The observation

flight must also conclude no longer than 96 hours after the team arrives at the Point

of Entry. This is designed to ensure that the visits do not disrupt exercises or

activities in the host country for an undue amount of time.

Mission Plans. The Treaty states that an observation team must present the

host with its mission plan when it arrives at the Point of Entry. This document

indicates what area of the host nation’s territory will be covered by the flight. It must

specify such details as the airfields the flight will use, the starting time and duration

of the flight, the distance the flight will travel, and a flight plan that specifies the route

and altitude for the flight.15 The host nation can propose changes to the mission plan,

for example, if weather conditions would affect flight safety, but it cannot deny the

observation team access to any area of its territory. The two parties must agree on

a plan within 8 hours of the time when the observation team arrives at the Point of

Entry.

Open Skies aircraft can also land at Honolulu International airport, Malmstrom Air Force

Base, Phoenix-Sky Harbor Airport in Arizona, General Mitchell International in Wisconsin,

and McGhee Tyson airport in Tennessee if they need to refuel.

Thomson, David B. The Treaty on Open Skies. Briefing, Center for National Security

Studies, Los Alamos National Laboratory v. 5, July 1994. p. 15.

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The Open Skies Treaty specifies that Open Skies observation flights will take

precedence over regular air traffic in the air traffic control system. If another aircraft

plans to fly along the same route at the same time as the Open Skies aircraft, the other

aircraft must alter its route. This is because a change in flight path or altitude of the

Open Skies aircraft could enhance or degrade the sensors operating on the aircraft

and, therefore, undermine the objectives of the observation flight.

The U.S. Federal Aviation Administration (FAA) has stated that giving

precedence to Open Skies aircraft will pose no threat or inconvenience to civil air

traffic in the United States.16 It frequently gives precedence to specified aircraft —

such as the President’s airplane, Air Force One — without passengers on other

aircraft knowing that their altitude or flight path has been altered. In addition, the Air

Force has concluded a formal agreement with the FAA that establishes a policy for

giving precedence to Open Skies flights. According to the Air Force, these policies

worked well during numerous Open Skies training and demonstration flights.17

The Open Skies Treaty contains several provisions to ensure that observation

flights do not pose an undue burden on the host nation. For example, nations can be

subject to only one observation flight at a time. This limit precludes both excessive

demands on the personnel who must implement the Open Skies provisions and an

unacceptable burden on national air traffic control system when it manages the flights

of the aircraft. The Treaty also specifies that an observation flight can not pass

repeatedly over the same spot or circle around a single area. This precludes efforts

to focus too much attention on a single facility or military activity.

Annual Quotas for Observation Flights

The Open Skies Treaty lists the number of flights that each nation must accept

over its territory each year — a passive quota. The passive quota is generally related

to the size of a nation’s territory. Each nation also has an active quota — a number

of flights that it can conduct each year. The Treaty specifies that no nation will be

allowed to conduct more flights over other nations’ territory than it is required to

receive over its own territory; i.e. the active quota for a nation cannot exceed the

passive quota for that nation. The Open Skies Consultative Commission (OSCC) is

charged with allocating the flights among the participating nations — i.e. each year

it prepares a list that specifies who will conduct flights over whom. The treaty states

that, when the OSCC allocates fights, no nation may conduct more than half of the

flights permitted by its active quota over the territory of one single party to the treaty

and no nation must receive a number of observation flights from a single nation that

equals more than half of the flights required by its passive quota.18

U.S. Congress. Senate. Committee on Foreign Relations. Treaty on Open Skies.

Hearing. p. 61.

Discussion with Air Force National Security Negotiations Division, October 18, 1995.

There is no requirement in the treaty for the actual number of flights conducted by a nation

to be equal to the number conducted over its territory. The actual number of flights will

depend on the requests of the other participants. If few participants seek flights over a

(continued...)

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Determining Passive and Active Quotas. Prior to the Open Skies

negotiations, analysts in the U.S. Defense Department and the intelligence community

concluded that, with sufficient notice, the United States could host one observation

flight per week without putting sensitive military activities and facilities at risk.19

Hence, when the negotiations began in 1990, the United States indicated that it would

be willing to accept 52 observation flights per year over U.S. territory. Because the

Soviet Union had more than twice the land mass of the United States, the United

States proposed that the Soviet Union accept 110 observation flights per year. In

response, the Soviet Union proposed that each alliance — NATO and the Warsaw

Pact — host 30 flights per year, with no more than half the flights occurring over any

one nation in the alliance.

When the participants abandoned efforts to devise a treaty between the two

opposing alliances in late 1990, the United States accepted a NATO proposal to

allocate quotas for observation flights on a national basis. At that time, the United

States suggested that the Soviet Union accept 52 flights per year, as the United States

was willing to do. The Soviet Union refused, but it did raise the number of flights it

was willing to receive from 15 to 25. After the abortive coup in Moscow in 1991, the

Soviet Union agreed to accept 52 flights per year. After the December 1991 demise

of the Soviet Union, Russia stated that it would accept 40 flights per year, based on

its relative size compared to the Soviet Union.20 The negotiators reached agreement

at 42 flights per year for the United States and Russia. (Russia has formed a group

with Belarus, so these 42 flights will cover both of those two nations.) The other

participants will receive between 4 and 12 flights per year, depending on the size of

their territories.

Allocation of Observation Flights Among the Parties. Open Skies

observation flights will be allocated on an annual basis by the Open Skies Consultative

Commission (OSCC). Each of the parties to the treaty will submit a list of the

observation flights it wishes to conduct during the coming year. If the parties request

more flights over a particular nation than allowed by that nation’s passive quota, the

OSCC will divide the number of permitted flights among the requesting parties. As

a result, all participants may not be able to conduct all of their requested flights. At

the same time, the treaty permits two or more nations to join together on observation

flights and essentially “share” the passive quota of observed nation. This will allow

nations to participate in more observation flights without exceeding the passive quota

of the observed nation. In addition, all parties to the Open Skies Treaty can purchase

data collected during any nation’s observation flights. Hence, all nations will have

access to information about the other parties’ military forces and activities, even if

they do not conduct their own observation flights.

(...continued)

nation’s territory, so that its passive quota is not filled, that nation can still conduct the full

number of flights permitted by its active quota.

Tucker, Back To the Future: The Open Skies Talks, p. 21.

U.S. Congress. Senate. Committee on Foreign Relations. Treaty on Open Skies.

Hearings. p. 40.

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Passive and Active Quotas for the United States. The Open Skies Treaty

gives the United States a passive quota, and therefore, an active quota, of 42

observation flights per year. These are the maximum number of flights the United

States could conduct or receive each year. However, when nations requested flights

for the first year of treaty implementation, only one party to the treaty — the group

of Russia and Belarus — requested flights over the United States. And this group

requested only 4 flights over the United States. The United States submitted a

request for its maximum permitted number of flights over other parties, but it

requested flights over many of the same nations that other participants wanted to visit.

As a result, when the OSCC allocated flights for the first year of treaty

implementation, the United States received only 8 flights — over Russia and Belarus.

It will also conduct one flight jointly with Canada over Ukraine. Because the OSCC

will reallocate flights each year that the treaty remains in force, the United States may

be granted a greater number of its requested flights in future years.

Permitted Aircraft

The Open Skies Treaty specifies that observation flights must be conducted by

unarmed, fixed-wing aircraft. These aircraft can be provided by either the observing

party or the observed party, if the observed party requests to use its own plane. The

parties cannot use helicopters for their observation flights.

During the negotiations, the United States and NATO proposed that the nation

conducting the observation flight provide the aircraft for the flight. The Soviet Union,

on the other hand, proposed that the nation hosting the observation flight provide its

own aircraft, or that all nations rely on the same fleet of dedicated Open Skies

aircraft.21 This proposal reflected Soviet concerns about the quality of data that could

be collected by aircraft using Western sensor technologies and Soviet concerns about

the possible presence of illicit sensors on observation aircraft. The participants from

Eastern Europe also sought a common pool of aircraft because they did not want to

rely on Soviet technology for the observation flights. The United States and NATO

argued, however, that a common pool of aircraft would be costly and difficult to

maintain. Nonetheless, they agreed that the Soviet Union could provide its own

aircraft for flights over Soviet territory in exchange for Soviet agreement to open all

its territory to observation flights. In addition, nations can borrow or lease aircraft

from other parties to the treaty so that all parties can conduct Open Skies observation

flights even if they cannot afford their own aircraft.

U.S. Aircraft. The United States is planning to equip 3 aircraft specifically for

Open Skies observation flights. The first is already operational; it is based at Offut

Air Force base in Nebraska and is used to conduct testing and training flights for

Open Skies personnel. Once the treaty enters into force, this aircraft will be used for

training flights and as a backup aircraft for observation flights. The other two aircraft

were reached full operational capability during 1996, one by the middle of the year

and the second by the end of the year.

U.S. Congress. Senate. Committee on Foreign Relations. Treaty on Open Skies.

Hearing. p. 42.

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Permitted Sensors

Open Skies aircraft can be equipped with four types of sensors: optical

panoramic and framing cameras (cameras for still photography) with a ground

resolution of 30 centimeters (around 1 foot); video cameras with a ground resolution

of 30 centimeters (around 1 foot); infrared line-scanning devices with a ground

resolution of 50 centimeters (around 20 inches); and sideways-looking synthetic

aperture radars (SARs) with a ground resolution of 3 meters (around 8 feet).

According to U.S. officials, these sensors will be able “to recognize major pieces of

military equipment. This has been characterized, for example, as the ability to tell the

difference between a tank and a truck... This level of capability is not sufficiently

detailed to reveal technical information about the major items of equipment, nor

would it permit identification of particular models of a category of equipment in most

instances.”22

The United States and NATO initially proposed that the Open Skies Treaty

impose no restrictions on the capabilities of the Open Skies sensors, with the

exception of a ban on “signals intelligence” sensors that could eavesdrop on electronic

communications.23 The sensors that NATO wanted to employ — including still and

video cameras, infrared line scanning devices, synthetic aperture radars, spectrometers

and air-sampling devices — would have permitted the collection of both photographic

data on visible activities and scientific data on activities inside facilities (such as the

manufacture of chemical agents). The Soviet Union, on the other hand, wanted the

treaty to permit only optical cameras. The United States, NATO, and Eastern

European participants rejected the Soviet approach because it would have severely

limited the quantity and quality of information collected during the observation flights.

The Soviet Union eventually agreed that the participants could use infrared sensors

and synthetic aperture radars; in exchange, NATO dropped its proposal for the use

of a wider variety of sensors.24

During the negotiations, the participants also disagreed about the resolution that

would be permitted on the sensors and determining the level of detail the data would

show. NATO proposed that optical cameras provide a ground resolution of 7.5

centimeters (about 3 inches); the Soviet Union suggested 30 centimeters (about 1

foot). For the synthetic aperture radar,25 NATO sought a resolution of 3 meters

(about 8 feet); the Soviet Union suggested 10 meters (about 30 feet). The two sides

U.S. Congress. Senate. Committee on Foreign Relations. Treaty on Open Skies.

Hearing. p. 44.

Tucker, Back to the Future: The Open Skies Talks, Arms Control Today, v. 20, October

1990, p. 23.

U.S. Congress. Senate. Committee on Foreign Relations. Treaty on Open Skies.

Hearing. p. 41.

A synthetic aperture radar is capable of looking “around” clouds and, therefore, can collect

data regardless of weather conditions on the ground.

CRS-10

eventually agreed to use the Soviet proposal for optical cameras and the NATO

proposal for SARs.26

Sensor Quality. The Open Skies Treaty specifies the sensors must be derived

from “off-the-shelf” technology available to all the parties. This responds to the

Eastern European nations’ concerns about being at a disadvantage if they had to rely

on Russian technology for their data collection. Off-the-shelf sensors may collect a

lower quality of data than the state-of-the-art technologies NATO had hoped to use.

At the same time, the use of off-the-shelf technology made it possible for all nations

to share the data collected by any nation during an observation flight.

The treaty contains a provision that allows the parties to approve the use of

improved sensors and additional types of sensors on observation flights. This

provision not only allows the participants to take advantage of technological

advances, but would allow them to expand the objectives of the treaty into areas such

as monitoring air quality for environmental protection. The Open Skies Consultative

Commission would have to approve proposals for new sensors; if any participant

objected, the sensors would not be used.

The treaty contains several provisions to address concerns about the possible

presence of unauthorized sensors on board Open Skies Aircraft. First, at Russian

insistence, the treaty permits any nation to request that its own aircraft be used for

observation flights. Second, the treaty permits the nation hosting the observation

flight to fully inspect the observing nation’s aircraft to ensure that it does not carry

covert sensors and to conduct calibration exercises to ensure that sensors do not have

capabilities in excess of those permitted by the treaty. Finally, when the nation

conducting the observation flight prepares its mission plan, it must make sure that the

aircraft’s altitude throughout the flight, when combined with the calibration of the

sensors, is consistent with the limits on sensor resolution; cameras would have better

resolution if the aircraft flew closer to the ground.

Treaty Participation

The original 25 signatories of the Open Skies Treaty include all of the members

of NATO and the former Warsaw Pact, along with Russia, Ukraine, and Belarus from

the former Soviet Union. The other newly independent states from the former Soviet

Union, including the Baltic states, can join the pact at any time; Georgia and

Kyrgyzstan have already done so. All other European nations who are members of

the Organization on Security and Cooperation in Europe can apply to join the treaty

during the first six months after the treaty enters into force.

The Open Skies treaty also contains provisions to expand beyond Europe, the

United States, and Canada. After the treaty has been in force for six months, the

Open Skies Consultative Commission can consider a request to join from any other

nation that it considers able to contribute to the objectives of the treaty. Because the

U.S. Congress. Senate. Committee on Foreign Relations. Treaty on Open Skies. Hearing.

p. 41.

CRS-11

OSCC must make its decisions by consensus, a nation’s application to join the treaty

will be rejected if any one of the current participants objects.

Current Status and Implementation Plans

Status of Treaty Ratification

U.S. Ratification. President Bush presented the Open Skies Treaty to the

United States Senate on August 12, 1992. The Senate Foreign Relations Committee

held hearings on the Treaty in September 1992 and March 1993. The Senate Armed

Services and Intelligence Committees also reviewed the treaty. The full Senate gave

its consent to ratification of the Treaty in August 1993. The United States officially

ratified the treaty on November 3, 1993.

In their reports, the three Senate committees that reviewed the treaty highlighted

several concerns about the costs of implementation and the possible implications for

U.S. security. All three were concerned about the cost of a fleet of three fullyequipped aircraft, which the Department of Defense believed it needed to conduct all

42 observation flights each year. The committees noted that the United States would

collect little new information during these flights and, therefore, might not need to

conduct 42 flights.27 The committees also expressed concerns about the addition of

new sensors to Open Skies aircraft; they noted that these sensors might not only add

to the costs of Open Skies implementation but might also eventually put U.S. national

security at risk.28

The Senate attached two conditions to its resolution of ratification for the Open

Skies Treaty. First, the Senate found that “United States interests may not require the

utilization of the full quota of allowed observation flights or the procurement of more

than one or two observation aircraft.”29 As a result, the Senate called on the President

to submit a report after the first year of treaty implementation that reviewed the

operation of the Treaty and provided an analysis estimating the number of annual

observation flights and aircraft that the United States would need for the duration of

the Treaty. Second, the resolution stated that the President should provide the Senate

with prompt notification of proposed improvements to Open Skies sensors and should

not provide U.S. approval to the proposed changes until 30 days after the Senate

received the notification.30 This time period would presumably be used to assess the

costs of the new sensors and possible implications for U.S. security.

U.S. Congress. Senate. Committee on Foreign Relations. Treaty on Open Skies. Report

103-5. p. 15.

U.S. Congress. Senate. Committee on Foreign Relations. Treaty on Open Skies. Report

103-5. p. 14.

The Resolution of Ratification in reprinted in Congressional Record, v. 139, August 2,

1993. p. S10106.

Congressional Record, v. 139, August 2, 1993. p. S10106.

CRS-12

Ratification by Other Parties. The Open Skies Treaty has been ratified by all

the participants except Russia, Belarus and Kyrgyzstan. The Ukrainian parliament

voted on the treaty three times without reaching consensus, but eventually did so and

Ukraine ratified the treaty on March 2, 2000. Reports indicate that the delay in these

nations can be attributed to their concerns about the cost of implementation. Each of

these nations is facing economic difficulties. Officials in Russia, Ukraine, and Belarus

have complained about the costs of implementing arms control agreements, such as

the Strategic Arms Reduction Treaty (START I) and the Conventional Armed Forces

in Europe Treaty (CFE). The treaty cannot enter into force until Russia and Belarus

approve its ratification.

Planning for Implementation in the U.S.

Interagency Participation. Policy decisions affecting the implementation of the

Open Skies Treaty will be addressed in an interagency committee with representatives

from the Department of Defense, the Department of State, and the intelligence

community.31 This group will address questions about a number of issues, including

the number of observation flights the United States should request over specific

nations and the areas of those nations that should be covered by each flight.

The United States Air Force and the On-Site Inspection Agency (OSIA), which

is now a part of the Defense Threat Reduction Agency, will take the lead in

implementing Open Skies observation flights for the United States. The Air Force

will own, operate, and maintain the U.S. Open Skies Aircraft. Representatives from

OSIA will operate the sensors during U.S. observation flights and participate as

escorts and observers in observation flights other nations conduct over U.S. territory.

Open Skies Aircraft. The United States had initially planned to deploy 3 fully

operational observation aircraft to support 42 observation flights per year. However,

in response to congressional concerns about the cost of these aircraft, the Air Force

now plans to outfit only two aircraft with the full suite of sensors needed to conduct

observation flights. The third aircraft, which is currently conducting testing and

training flights for Open Skies personnel, is equipped with only the optical cameras

permitted by the treaty. It will not be modified to carry the infrared sensor or

synthetic aperture radar.

The United States Air Force, which will operate the Open Skies Aircraft, is

modifying existing C-135 airplanes for the Open Skies mission. Similar in size to

civilian 707 aircraft, these modified OC-135 airplanes will seat 38 people, including

the Air Force flight crew and maintenance crew, representatives from the country that

is hosting the U.S. observation flight, and crew members from the On-site Inspection

Agency who will help with mission planning and operate the aircraft’s sensors.

Because the Air Force has decided to modify existing aircraft, there will be no

expense associated with the purchase of new aircraft. Nonetheless, the Air Force is

spending around $62 million to equip the aircraft with sensors and other equipment

needed for Open Skies observation flights. It also plans to spend an additional $7.3

U.S. Congress. Senate. Committee on Foreign Relations. Treaty on Open Skies. Hearing.

p. 62.

CRS-13

million on research and development for new sensors and integration of sensors and

aircraft.

Trial and Training Flights. The United States has participated in more than

50 training and trial flights since 1993. Crews assigned to the aircraft at Offut Air

Force Base conduct, on average, two training flights per month to maintain their

proficiency in operating the aircraft. U.S. crews have also participated in trial flights

to certify that the aircraft and sensors operate in accordance with U.S. and treaty

requirements and to support ongoing OSCC discussions about procedures that will

be used during official observation flights.32

The United States has also conducted several flights in cooperation with other

parties to the treaty. These flights carry participants from both nations and are used

to test the procedures for mission planning and mission implementation. In June

1998, the United States conducted training flights over Ukraine. This effort was

designed not only to exercise U.S. mission procedures, but also to demonstrate these

procedures to officials in Ukraine, in part to show that these procedures would not

be too costly or intrusive to implement.

Other treaty signatories have also conducted trial inspection flights. For

example, in June 1995, the German Open Skies aircraft conducted trial flights over

U.S. territory. This was the first time that a foreign military aircraft had ever had

unrestricted access to U.S. airspace.33 Russia has also conducted a training mission

over the United States, with its aircraft visiting U.S. territory during August 1997.

Russia also conducted a training flight over Bulgaria in April 1998, and hosted a

training flight over Russian territory in August 1998. The German crew used a

Russian aircraft for its observation flight. In July 1998, Germany had announced that

it would no longer use its own aircraft to participate in Open Skies flights.34 The first

aircraft that it modified for this purpose had crashed in 1997 and it suspended plans

to modify a second aircraft. Analysts were uncertain as to whether the German

decision would affect the ratification and implementation of the Open Skies Treaty.

When the treaty enters into force, the Department of Defense has estimated that

it might cost the United States $20-25 million per year to conduct and host

observation flights. Some have estimated that it could cost the United States

$25,000-$35,000 to host an Open Skies observation flight and $165,000-$170,000

to conduct an observation flight using the U.S. aircraft.35 These are primarily the

costs of training and employing the personnel needed to operate the aircraft and the

sensors and the actual costs of flying the aircraft.

Discussions with the Air Force National Security Negotiations Branch, October, 18, 1995.

Information provided by the On-site Inspection Agency, October 20, 1995.

Defense Ministry Withdraws from Control Flights. Main Frankfurter Allegemeine. July

9, 1998. Translated in FBIS-WEU-98-190.

U.S. Congress. Senate. Committee on Foreign Relations. Treaty on Open Skies. Report,

103-5. pp. 170-172.

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Implications for the United States

Most analysts and observers agree that the Open Skies Treaty can play a valuable

role as a confidence building measure among the nations of NATO and the former

Warsaw Pact. At the same time, some have questioned U.S. participation in the Open

Skies regime. These questions have focused on two key areas: the value of the

information the United States might collect during Open Skies observation flights and

the cost to U.S. security of the information that others might collect during flights

over U.S. territory.

Value of Information

Several analysts and some Members of Congress have noted that the United

States does not need to bear the costs of equipping and operating Open Skies aircraft

to acquire information about the military forces and activities of other nations. It

already operates expensive photo reconnaissance satellites that serve the same

purpose. Some have proposed, therefore, that the United States conduct few

observation flights and limit its participation in the treaty.36

Most supporters of the Open Skies regime have acknowledged that the United

States will not acquire much new information during its Open Skies observation

flights. Nonetheless, as Ambassador John Hawes, the U.S. representative to the Open

Skies Conference, noted during his testimony before the Senate Foreign Relations

Committee:

For most of the other participants, however, the ability to utilize the Open Skies

sensor suite to observe the full territory of the other participating countries will

represent a new and very significant enhancement in their ability to gather securityrelated information. The United States will ... be a major indirect beneficiary of

this increase in knowledge, confidence, and security of the participants.37

The treaty’s supporters have also noted that the United States might acquire

information during Open Skies observation flights that is more useful than satellite

data for international relations purposes. For example, the United States is often wary

of releasing satellite photographs that could reveal secret information about U.S.

satellite capabilities. But similar information acquired during Open Skies flights could

be used in the international arena.38

This point is made in the report of the Senate Select Committee on Intelligence. See U.S.

Congress. Senate. Committee on Foreign Relations. Treaty on Open Skies. Report 103-5.

p. 137.

U.S. Congress. Senate. Committee on Foreign Relations. Treaty on Open Skies. Report

103-5. p. 157.

See the prepared statement of Thomas Karas, Office of Technology Assessment, in U.S.

Congress. Senate. Committee on Foreign Relations. Treaty on Open Skies. Hearing. p. 35.

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Security Concerns

Although most analysts acknowledge that Russia, like the United States, does

not need to participate in the Open Skies Treaty to collect information about military

forces and activities in the United States, some have expressed concerns that nations

who currently lack access to satellite data could use Open Skies observation flights

to collect sensitive information about the U.S. military or U.S. industry. Some have

also expressed concern about the possibility that treaty participants could transfer

information collected during Open Skies observation flights to others, including rogue

nations or terrorists, who might use the information in planning operations against the

United States. These concerns would be heightened if the Open Skies regime allowed

the use of more sophisticated sensors or if the treaty were expanded to permit

participation by nations who remain hostile to the United States.

Officials from both the Bush and Clinton Administrations insisted during

testimony before the Senate Foreign Relations Committee that information collected

during Open Skies flights would not place U.S. national security at risk.39 A number

of factors would limit these nations’ ability to collect sensitive information. For

example, the treaty requires advance notice before flights begin and prohibits flights

from circling or returning to a specific area repeatedly during the flight.40 The

advance notice would allow the United States to cease any sensitive activities before

an observation flight began. The ban on repeat visits during a single flight would

complicate an observing nation’s effort to focus extra attention on a single facility or

military activity.

U.S. officials have also emphasized that the resolution of sensors permitted by

the Open Skies Treaty will not be sufficient to allow the collection of sensitive

intelligence about U.S. military forces and activities.41 The sensors will lack the

capability to identify the capabilities of weapons systems or the types of activities

occurring in closed structures. In addition, information about the size and location

of most major military installations in the United States is already available to the

public at large. Because the Open Skies observation flights would not provide any

additional information about activities occurring inside buildings, the flights would do

little to help those seeking targets for attack in the United States. Finally, it is

unlikely that the Open Skies Treaty would expand to include any nation that might use

Open Skies data to threaten a current participant. The Open Skies Consultative

Commission must approve all applications for admission. The treaty states that, if

According to Brig. Gen. Teddy E. Rhinebarger, who represented the Joint Chiefs of Staff

at the Senate hearings, “... the scope of the Open Skies regime was carefully considered, and

the overflight access Open Skies provides does not place sensitive facilities at risk.” see U.S.

Congress. Senate. Committee on Foreign Relations. Treaty on Open Skies. Hearing. p. 16.

See the prepared statement of Thomas Karas in U.S. Congress. Senate. Committee on

Foreign Relations. Treaty on Open Skies. Hearing. p. 33.

“The resolution limit of 30 centimeters for optical sensors establishes a level of

intrusiveness commensurate with the Treaty’s goal of openness and transparency in military

forces and activities while effectively safeguarding legitimate national security interests.” See

U.S. Congress, Senate, Committee on Foreign Relations, Treaty on Open Skies, Hearing. p.

44.

CRS-16

any one of the current parties to the treaty objects to an applicant, the OSCC would

have to reject the application.

Conclusion

The primary benefits of the Open Skies Treaty will accrue to its European

participants. These nations will not only be able to acquire information about military

forces and activities in neighboring nations, they will also be able to collect this

information themselves, without relying on the observation satellites of other nations.

Some observers believe the United States should limit its participation in the

Open Skies regime to reduce the costs of equipping and operating observation

aircraft. However, even if the United States reduces its own participation, it must

remain willing to host up to 42 observation flights from other countries each year. If

the first year’s plans are any indication, this should not create an undue burden; only

Russia and Belarus showed an interest in conducting flights over U.S. territory and

they only requested 4 flights.

Still, if the Open Skies Treaty remains in force for many years, the United States

could host dozens of visits by other participants, with foreign military aircraft

equipped with sensors flying over U.S. territory. Virtually all observers agree that

these flights will pose no security threat to the United States.

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Table 1. Parties to the Treaty on Open Skies

NATO Members

Eastern European Participants

United States

Russia

Belgium

Belarus

Canada

Czech Republic (a)

Denmark

Georgia (b)

France

Hungary

Germany

Kyrgyzstan

Greece

Poland

Iceland

Romania

Italy

Slovak Republic (a)

Luxembourg

Ukraine

Netherlands

Norway

Portugal

Spain

Turkey

United Kingdom

NOTES:

(a) The Czech and Slovak Republics each signed after they separated on Jan. 1, 1993.

(b) Georgia signed in 1992.

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