The Open Skies Treaty: Background and Issues

The Open Skies Treaty: Background
and Issues
Updated June 7, 2021
The United States announced its withdrawal from the Treaty on Open Skies on May 22, 2020; this
withdrawal took effect on November 22, 2020. Russia announced its plans to withdraw, while beginning
the domestic procedures for withdrawal on January 15, 2021. The Russian Duma approved the law
authorizing Russia’s withdrawal in May 2021, with the Federation Council following in early June.
President Putin signed the law on June 7, 2021; Russia’s withdrawal will be complete in early December
2021.
When it withdrew from the Treaty on Open Skies, the Trump Administration cited U.S. concerns about
Russian compliance. According to the U.S. State Department, Russia had restricted access for Open Skies
flights over Kaliningrad, over Moscow, and along the border between Russia and the Georgian regions of
South Ossetia and Abkhazia. Russia reportedly also failed to provide priority flight clearance for Open
Skies flights on a few occasions. Although some of these issues had been resolved during discussions in
the Open Skies Consultative Commission, the Trump Administration argued that the Treaty no longer
served U.S. national security interests.
While President Biden had disagreed during the campaign with the prior Administration’s decision to
withdraw from Open Skies, his Administration informed Russia on May 27, 2021 that the United States
would not rejoin the Treaty. In April, the Administration had told U.S. allies that it was concerned
rejoining the Treaty could “send the wrong message to Russia and undermine our position on the broader
arms control agenda” if Russia continued to violate Open Skies. In May, it cited concerns about Russia's
failure to return to compliance as the one of its key reasons for the U.S. withdrawal. Russian officials
criticized the U.S. decision, referring to it as a “political mistake” and a “missed opportunity to bolster
security in Europe.”
The U.S. Air Force has retired the two U.S. Open Skies aircraft. The first of the two moved from Offutt
Air Force Base in Nebraska to Davis-Monthan Air Force Base in Arizona in May 2021; the second moved
in early June 2021.
Background
President Eisenhower proposed an Open Skies agreement in 1955 to reduce the risk of war. Before
satellites existed, aerial overflights provided information for both intelligence and confidence-building
purposes. The Soviet Union rejected the proposal because it considered overflights equal to espionage and
believed the United States had more to gain than it did. President George H. W. Bush revived the proposal
in May 1989. By this time, both the United States and Soviet Union collected intelligence with satellites
and remote sensors. As Europe emerged from the East-West divide of the Cold War, the United States
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supported increased transparency to reduce the chances of military confrontation. The Open Skies Treaty
was one of three arms control arrangements—including the Vienna Document and the Conventional
Armed Forces in Europe Treaty (CFE)—which could serve, as then-Secretary of State Baker noted, as
“the most direct path to greater predictability and reduced risk of inadvertent war.”
The United States, Canada, and 22 European nations signed this treaty on March 24, 1992. It entered into
force on January 1, 2002, and had 34 members before the U.S. withdrawal. The parties permit unarmed
observation aircraft to fly over their entire territories to observe military forces and activities. The treaty is
designed to increase transparency, build confidence, and encourage cooperation among European nations.
Treaty Provisions
Open Skies participants make all their territory accessible to overflights by unarmed fixed-wing
observation aircraft. They can restrict flights for safety concerns, but cannot impede or prohibit flights
over areas, including military installations that would otherwise be off-limits. In most cases, the nation
conducting the observation flight provides the aircraft and sensors; officials from the host nation
participate in the flight.
The nation conducting an observation flight must provide 72 hours’ notice before arriving in the host
country. This provides the host with time to suspend sensitive military exercises or activities. The
observation team presents a mission plan, specifying details including the route and altitude for the flight.
The host nation can propose changes to the mission plan, due to weather or flight safety considerations,
but it cannot deny access to any area of its territory.
Open Skies aircraft can be equipped with four types of sensors that can collect basic information on
military forces and activities. The treaty limited the capabilities of the sensors so that they could not
provide detailed technical intelligence. It also allowed monitoring of military and civilian infrastructure,
such as industrial plants, airports, roads, and railway lines, but would not allow recognition of sensitive
details about items such as electronic equipment. The participants could upgrade cameras and sensors as
technology advanced, as long as the capabilities remained within treaty parameters.
Treaty Implementation
When the United States first signed Open Skies, most analysts agreed that the treaty would provide little
information not already available from observation satellites. But supporters argued that the treaty could
still benefit the United States and its allies. For example, most treaty participants do not have observation
satellites, so, as former Secretary of State George Schultz noted, “Open Skies is their only means of
alleviating security concerns through timely overhead imagery.” This reduces the risk of
misunderstandings or crises that could involve the United States and contributes to “a more stable and
secure European continent.”
In recent years, some U.S. military and intelligence officials cautioned that better optical technology
might allow Russia to overcome weaknesses in its satellite surveillance capabilities. Others, however,
questioned these conclusions, noting that Russia would operate commercially available cameras, with
resolutions that are both within the bounds established by the treaty and also less precise than those
offered by commercial satellites.
The parties conducted 1,500 observation flights through October 2019. Some parties provide their own
aircraft, but they can also join overflights on aircraft provided by other nations. Both the observing nation
and observed nation have access to the data from each flight; other parties can purchase the data, so all
can share information collected during all flights. According to the State Department, the United States
conducted nearly three times as many flights over Russia as Russia did over the United States. Further,

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the parties could invite flights over their territories in special circumstances, as Ukraine did in 2014, when
Open Skies flights helped monitor activities along the Ukraine-Russian border.

Author Information

Amy F. Woolf

Specialist in Nuclear Weapons Policy




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IN10502 · VERSION 12 · UPDATED

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