Originally proposed by President Dwight Eisenhower in 1955—but rejected by the Soviet Union—the Open Skies idea was revived by President George H. W. Bush in 1989 as a confidence-building measure to promote greater transparency regarding military installations, forces and activities. The Open Skies Treaty permits state parties to conduct unarmed observation flights over other state parties. It entered into force in 2002 and currently has thirty-four state parties—the United States, Canada, Russia, Kazakhstan and thirty other countries in Europe. All total, they have conducted more than fifteen hundred observation overflights.

For each state party or group of state parties, the treaty specifies an active quota, the number of observation overflights it may conduct per year, and a passive quota, the number of overflights it must accept. Observation aircraft can carry video and still cameras, infrared line scanners and synthetic aperture radars, though the capabilities of the equipment (e.g., resolution) are limited. When an Open Skies aircraft conducts an overflight, officials of the observed state party get to inspect the aircraft to ensure that it is carrying only permitted equipment and fly onboard.

Criticism of Open Skies

In October 2019, President Donald Trump reportedly signed a memorandum regarding his intention to withdraw from the Open Skies Treaty. The following month, U.S. officials briefed NATO on U.S. concerns and warned that the United States would probably leave the treaty. Treaty critics seem to have three principal concerns.

First, critics note that Russia has violated the treaty. Moscow restricts the distance that observation flights can fly over the exclave of Kaliningrad and bars flights along the Russian border with the Georgian-breakaway regions of South Ossetia and Abkhazia. The treaty limits flights near borders with non-state parties and the Russians argue that South Ossetia and Abkhazia are independent nations, a position few other countries recognize.

In response to the Russian violation, the United States has imposed roughly reciprocal limitations on Russian flights over U.S. territory, restricting, for example, overflights of Hawaii. Russia has violated the treaty, but Washington has responded proportionately within the treaty.

Second, opponents of the Open Skies Treaty argue that, over the past thirty years, commercial satellites have developed capabilities, such as camera resolution, similar to or better than the equipment carried on Open Skies aircraft. They assert that makes observation flights unnecessary and redundant.

Aircraft, however, are more flexible than satellites, which fly in fixed orbits. Moreover, aircraft can fly below cloud cover that can obscure photography taken from space.

Third, critics express concern that the Russians use observation flights to gather information on U.S. infrastructure as well as military facilities and activities. But how much of a threat is this? Critics seem to ignore the fact that, much like the United States, Russia operates imagery satellites whose capabilities are equal to or better than those permitted on Open Skies aircraft.

Advantages of Open Skies

U.S. withdrawal from the Open Skies Treaty would mean forgoing a number of advantages. First, Open Skies imagery and other data can be used in ways that U.S. satellite imagery, which is highly classified, cannot. U.S. officials explained publicly only in November 2018 the basis for their 2014 assessment that Russia had violated the 1987 Intermediate-range Nuclear Forces Treaty by testing a prohibited cruise missile. Satellite imagery almost certainly figured in that assessment, but that imagery remains closely held because the U.S. government wants to protect the capabilities of its satellites. Open Skies data, on the other hand, could readily be used to demonstrate a violation of an agreement or some threatening military activity.

Second, the United States conducts far more overflights of Russia and Belarus (the two are paired as a group of state parties) than vice-versa. According to the Department of State, during the first fifteen years of the treaty’s operation, the United States made 196 observation flights over Russia and Belarus while Russia/Belarus made just seventy-one flights over U.S. territory. Moreover, U.S. allies conducted five hundred other flights over Russia and Belarus.

Third, few countries possess the sophisticated space-based reconnaissance capabilities that the United States and Russia have. The treaty allows other states parties to conduct overflights and directly gather confidence-building data. U.S. allies value Open Skies; a number, including Germany, France and Britain, have urged Washington to remain within the treaty.

Fourth, Open Skies can provide a particularly useful tool in times or regions of crisis. Russian and Russian proxy forces have been in conflict with Ukrainian forces in the Donbas region since spring 2014. The United States has targeted observation flights—sometimes in cooperation with Ukraine—at Donbas and Russian territory bordering Donbas. These overflights not only gather data but send a signal of U.S. political support to Ukraine.

U.S. Withdrawal?

Should Trump unwisely decide to withdraw from the treaty, it could mean the treaty’s end. With Russia no longer having the possibility of flights over the United States, it might also withdraw. That would likely provide the death knell for the treaty; with just NATO members and a few neutral states remaining in the agreement, what would be the point? Alternatively, Moscow could choose to remain in the treaty, which would highlight the U.S. absence (and allow Russian overflights to continue over American military facilities and activities in Europe).

In either case, political blame would fall on the United States. Given allied support for continuing the treaty, a U.S. withdrawal would be seen in Europe as one more instance where Washington ignored the views of its NATO partners.

Withdrawal would constitute yet another blow to arms control inflicted by the Trump administration. It left the Joint Comprehensive Plan of Action regarding Iran. It refused to seek ratification of the Comprehensive Test Ban Treaty (even though it seems to see no reason for nuclear testing). It eschewed political and military steps that would have increased pressure on Russia to return to compliance with the INF Treaty. It so far refuses Moscow’s offer to extend the 2010 New Strategic Arms Reduction Treaty, which expires in eleven months.

Trump over the past year has said that he wants to go big on arms control and negotiate an agreement with Russia and China covering all types of nuclear arms, but his administration has yet to offer a proposal or even an outline for doing so. A decision to withdraw from the Open Skies Treaty would provide the latest evidence that he sees little point in arms control.

Steven Pifer is a William Perry Research Fellow at Stanford’s Center for International Security and Cooperation. 

Originally for The National Interest