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 You are in: Under Secretary for Arms Control and International Security > Bureau of International Security and Nonproliferation (ISN) > Releases > Fact Sheets > 2001
Fact Sheet
Bureau of Arms Control
Washington, DC
April 1, 2001

The Open Skies Treaty

The Treaty on Open Skies establishes a regime of unarmed aerial observation flights over the territories of its signatories. The Treaty is designed to enhance mutual understanding and confidence by giving all participants, regardless of size, a direct role in gathering information through aerial imaging on military forces and activities of concern to them. Open Skies is one of the most wide-ranging international arms control efforts to date to promote openness and transparency in military forces and activities.

Current Status:

The original concept for the Treaty was first proposed by President Eisenhower in 1955. An initiative of Former President Bush in 1989, the Open Skies Treaty was signed in Helsinki, Finland, on March 24, 1992. It was negotiated between the members of NATO and members of the former Warsaw Pact; the latter dissolved during the course of the talks. The following states have signed the Open Skies Treaty: Belarus, Belgium, Bulgaria, Canada, Czech Republic, Denmark, France, Georgia, Germany, Greece, Hungary, Iceland, Italy, Kyrgyzstan, Luxembourg, the Netherlands, Norway, Poland, Portugal, Romania, Russia, the Slovak Republic, Spain, Turkey, the United Kingdom, Ukraine, and the United States.

Twenty-four of the 27 signatories have ratified the Treaty. Remaining are Russia and Belarus, whose ratification is required for entry-into-force (EIF). There are as well 17 Observer States, some of whom may apply to accede to the Treaty after EIF. The Open Skies Treaty was submitted to the U.S. Senate for its advice and consent on August 12, 1992. On November 2, 1993, then-President Clinton signed and ratified it. The Treaty will enter-into-force 60 days after the deposit of 20 instruments of ratification, representing those of the two depositaries (Canada and Hungary) and those States Parties with a passive quota of eight or more (Belarus, France, Germany, Italy, Russia, Turkey, United Kingdom, and the United States). Portions of the Treaty have been provisionally applied since signature.

Basic Elements of the Treaty:

  • Territory: The Treaty specifies that territories of all States Parties are open to observation. An Observed States Party may not restrict observation flights for national security reasons, only for legitimate reasons of flight safety or the inability of its airfields (Open Skies, alternate, or refueling) to support the mission.

  • Aircraft: Observation aircraft may be provided by either the observing State Party or the observed State Party at the latter's option. All Open Skies aircraft and sensors must pass specific certification and pre-flight inspection procedures to ensure they meet Treaty standards and that only Treaty-permitted sensors are installed. The U.S. Open Skies aircraft is the OC-135B aircraft (a military version of the Boeing 707).

  • Sensors: Open Skies aircraft may have video, optical panoramic and framing cameras for daylight photography, infra-red line scanners for a day/night capability, and synthetic aperture radar for all-day/all-night and all-weather capability. Photographic image quality will permit recognition of major military equipment (e.g., be able to distinguish a tank from a truck) sufficient for rendering meaningful transparency of military forces and activities. Sensor categories may be added and capabilities improved on unanimous agreement by States Parties. All observation sensor equipment used in Open Skies must be commercially available to all participants.

  • Quotas: Each State Party has an annual quota of observation flights it is willing to receive over its own territory -- its passive quota of observation flights. Each State Party may also conduct as many observation flights over other signatories -- its active quota -- as its passive quota. The full passive quota for the U.S. and the Russia/Belarus Group of States Parties is 42 flights each. During the first three years after EIF, countries will have to accept only 75% of their passive quota. Thus, the initial U.S. and Russia/Belarus passive quota are 31 flights each. For the first year of the Treaty's operation, only 4 of the 31 potential flights over the United States were requested, all by Russia/Belarus. The United States is entitled to 8 of the 31 flights available over Russia/Belarus. Additionally, the United States is entitled to one flight over Ukraine to be shared with Canada.

  • Data Availability: The Treaty provides that the observing State Party will provide to the observed State a copy of the sensor data it collects during a mission over the observed State. In addition, all States Parties have the right to purchase a copy of the data collected by any State. As a result, the data available to each State Party is much greater than that which it can collect itself under the Treaty quota system.

Future Membership:

Other states on the territory of the former Soviet Union are eligible to sign the Treaty at any time. Other members of the Organization for Security and Cooperation in Europe (OSCE) may apply for participation in the Open Skies regime as soon as the Treaty enters into force. Six months after EIF, the Treaty will be open to application for participation by all other interested states. Applications for participation after EIF are subject to consensus agreement by the Open Skies Consultative Commission (OSCC), a forum of all States Parties charged with facilitating the implementation of the Treaty.

Point of Contact for Further Information:

Department of State
Arms Control Bureau
Office of Conventional Arms Control

Recommended Reading:

Fact Sheet: The Open Skies Treaty: Typical Observation Mission, Department of State, Public Affairs, April 2001

The Treaty on Open Skies, by Staff Sergeant Kirk W. Clear, USAF and Steven E. Block.
Published April 1999 by:
Defense Threat Reduction Agency (DTRA)
Office of History
45045 Aviation Drive
Dulles International Airport
Dulles, VA 20166-7517
history@dtra.mil; http://www.dtra.mil 

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