The Treaty on Open Skies entered into force on January 1, 2002, and currently has 34 States Parties. It establishes a program of unarmed aerial surveillance flights over the entire territory of its participants. The treaty is designed to enhance mutual understanding and confidence by giving all participants, regardless of size, a direct role in gathering information about military forces and activities of concern to them. Open Skies is one of the most wide-ranging international efforts to date promoting openness and transparency of military forces and activities. The concept of "mutual aerial observation" was initially proposed to Soviet Premier Bulganin at the Geneva Conference of 1955 by President Eisenhower; however, the Soviets promptly rejected the concept and it lay dormant for several years. The treaty was eventually signed as an initiative of President (and former Director of Central Intelligence) George H. W. Bush in 1989. Negotiated by the then-members of NATO and the Warsaw Pact, the agreement was signed in Helsinki, Finland, on March 24, 1992. The United States ratified it in 1993.
This treaty is not related to civil-aviation open skies agreements.
The treaty is of unlimited duration and open to accession by other States. States of the former Soviet Union that have not already become States Parties to the treaty may accede to it at any time. Applications from other interested States are subject to a consensus decision by the Open Skies Consultative Commission (OSCC), the Vienna-based organization charged with facilitating implementation of the treaty, to which all States Parties belong. Eight states have acceded to the treaty since entry into force: Finland, Sweden, Latvia, Bosnia-Herzegovina, Croatia, Slovenia, Estonia, and Lithuania. Cyprus’s application for accession is pending before the OSCC.
Observation aircraft may be provided by either the observing Party or (the "taxi option") by the observed Party, at the latter's choice. All Open Skies aircraft and sensors must pass specific certification and pre-flight inspection procedures to ensure that they are compliant with treaty standards. The official certified U.S. Open Skies aircraft is the OC-135B Open Skies (a military version of the Boeing 707). The United Kingdom's aircraft is a modified Hawker Siddeley Andover CMk 1, XS 641.
Canada uses a C-130 Hercules aircraft equipped with a "SAMSON" sensor pod to conduct flights over other treaty nations. The pod is a converted CC-130 fuel tank modified to carry the permitted sensors, along with associated on-board mission systems. A consortium of nations consisting of Belgium, Netherlands, Luxemburg, Canada, France, Greece, Italy, Norway, Portugal, and Spain own and operate this system. The costs of maintaining the SAMSON Pod are shared, based on each nation's flight quota and actual use.
In February 1990, an international Open Skies conference involving all NATO and Warsaw Pact countries opened in Ottawa, Canada. Subsequent rounds of negotiations were held in Budapest, Hungary, Vienna, Austria, and Helsinki, Finland.
On March 24, 1992, the Open Skies Treaty was signed in Helsinki by Secretary of State James Baker and foreign ministers from 23 other countries. The treaty entered into force on January 2 2002, after Russia and Belarus completed ratification procedures.
In November 1992, President Bush assigned responsibility for overall training, management, leadership, coordination and support for U.S. Open Skies observation missions to the On-Site Inspection Agency (OSIA), now a part of the Defense Threat Reduction Agency (DTRA). Until entry into force in January 2002, DTRA support for the treaty involved participating in training and joint trial flights (JTFs). The U.S. has conducted over 70 JTFs since 1993. By March 2003, DTRA had successfully certified 16 camera configurations on the OC-135B aircraft. They also had contributed to the certification of the Bulgarian AN-30, Hungarian AN-26, POD Group (consisting of Belgium, Canada, France, Greece, Italy, Luxembourg, Netherlands, Norway, Portugal and Spain) C-130H, Russian AN-30, and Ukrainian AN-30. The United States successfully flew its first Open Skies mission over Russia in December 2002.
With entry into force of the treaty, formal observation flights began in August 2002. During the first treaty year, States Parties conducted 67 observation flights. In 2004, States Parties conducted 74 missions, and 110 missions are planned for 2005. On March 8 and 9, 2007, Russia conducted overflights of Canada under the Treaty
The OSCC continues to address modalities for conducting observation missions and other implementation issues.
In the summer of 2008, states plan to commemorate the 500th observation flight carried out under the Treaty.