Open Skies Treaty

The Treaty on Open Skies was signed in Helsinki on 24 March 1992 and entered into force on 1 January 2002. It grew out of a 1955 proposal by U.S. President Dwight Eisenhower at the Geneva Summit, which the Soviet Union initially rejected, and was revived by President George H.W. Bush in 1989 as the Cold War wound down.

The treaty permits each state party to conduct a quota of short-notice, unarmed observation flights over the entire territory of any other state party, using aircraft equipped with agreed sensors (optical panoramic and framing cameras, video cameras, infrared line-scanners, and synthetic aperture radar). Imagery collected on a flight must be made available to any other state party on request, creating a shared pool of overhead data. Sensor resolutions, flight quotas, and certification procedures are negotiated through the Open Skies Consultative Commission in Vienna.

The regime was designed to complement the Conventional Armed Forces in Europe (CFE) Treaty and confidence- and security-building measures under the OSCE, by giving smaller states without satellite reconnaissance capabilities access to verification imagery. Membership grew to 34 states across North America, Europe, and the Caucasus, including Russia, the United States, Canada, the United Kingdom, Germany, France, Turkey, and Ukraine.

The regime has eroded significantly. The Trump administration announced U.S. withdrawal in May 2020, citing alleged Russian restrictions on flights over Kaliningrad, the Russia–Georgia border area, and military exercises; the United States formally exited on 22 November 2020. Russia announced its own withdrawal in January 2021 and completed it on 18 December 2021. The treaty remains in force among the remaining parties, but its utility has been substantially reduced, and its future is widely viewed as uncertain following Russia's 2022 invasion of Ukraine.