Open Skies Treaty

Model Diplomat Research Team · Last reviewed June 22, 2026

TL;DR

A multilateral arms-control treaty allowing signatories to conduct unarmed aerial surveillance flights over each other's territory to build military transparency.
When did the Open Skies Treaty enter into force?
Why did the United States withdraw?
Is the treaty still in force?

Global AffairsUpdated June 22, 2026

A multilateral arms-control treaty allowing signatories to conduct unarmed aerial surveillance flights over each other's territory to build military transparency.

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Timeline

24 March 1992
The Treaty on Open Skies was signed in Helsinki on and entered into force on 1 January 2002.
1 January 2002
The Treaty on Open Skies was signed in Helsinki on 24 March 1992 and entered into force on .
22 November 2020
withdrawal in May 2020, citing alleged Russian restrictions on flights over Kaliningrad, the Russia–Georgia border area, and military exercises; the United S…
18 December 2021
Russia announced its own withdrawal in January 2021 and completed it on .

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In 2019, a U.S. OC-135B aircraft conducted an Open Skies observation flight over Russian territory before the United States announced its withdrawal from the treaty in May 2020.

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Timeline

24 March 1992

The Treaty on Open Skies was signed in Helsinki on and entered into force on 1 January 2002.

1 January 2002

The Treaty on Open Skies was signed in Helsinki on 24 March 1992 and entered into force on .

22 November 2020

withdrawal in May 2020, citing alleged Russian restrictions on flights over Kaliningrad, the Russia–Georgia border area, and military exercises; the United S…

18 December 2021

Russia announced its own withdrawal in January 2021 and completed it on .

Research it like a delegate

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.

Frequently asked questions

When did the Open Skies Treaty enter into force?

It was signed in Helsinki on 24 March 1992 and entered into force on 1 January 2002 after the required ratifications.

Why did the United States withdraw?

The Trump administration announced withdrawal in May 2020, citing Russian non-compliance, including restrictions on flights over Kaliningrad and near the Georgian border. Withdrawal took effect on 22 November 2020.

Is the treaty still in force?

Yes, it remains in force among the remaining state parties, but both the United States (2020) and Russia (2021) have withdrawn, sharply reducing its practical value.