The Open Skies Treaty permits each signatory to conduct a set number of unarmed reconnaissance flights with sensor equipment over other member states at short notice, allowing them to collect data on military forces and quelling fears of secretive military build-ups. The data collected on the flight, which includes representatives of the surveilling and surveilled countries, is to be shared with all the signatories. This makes the treaty particularly important for U.S. allies in Europe who don't have the sophisticated satellites the U.S. has.
The decision was swiftly condemned by arms control advocates, who argued U.S. withdrawal is counter-productive and issues with Russian compliance should be dealt with through the treaty.
The withdrawal is "another retreat from international security cooperation," according to retired Ambassador Laura Kennedy, who served as U.S. envoy to the U.N.-affiliated Conference on Disarmament. "In an age where we need allies more than ever, we are disastrously going it alone."
European allies like France and Germany have urged the U.S. to remain one of the pact's 35 members, pointing to the over 1500 successful flights since the treaty entered into force in 2002.
"While the intelligence and confidence building advantages are limited for the United States itself, they are very real for America's NATO allies," over a dozen former senior European defense officials said in a joint letter last week, adding, "The political symbolism matters: U.S. withdrawal would prevent the United States from overflying Russia, but would leave Russia still able to overfly American military activities and installations in Europe. U.S. departure would also further weaken the international arms control architecture and be a further blow to any global sense of stability."
Senior Trump officials, however, said Russia had violated the terms of the pact and a broader spirit of "cooperative security" in recent years, pointing to Russia's invasion of Georgia and Ukraine where it continues to occupy territory, its deployment of a cruise missile system in violation of the Intermediate-Range Nuclear Forces (INF) Treaty, and its use of Novichok nerve agent against a former spy in the U.K. in violation of the Chemical Weapons Convention.
"Russia has systematically destroyed conventional arms control in Europe," said special envoy Billingslea. "If the other party is not holding up their end of the bargain, we do have the right to withdraw from the arrangement."
In particular, U.S. officials point to Russia's denial of flights over a military exercise last fall and limits on flights near territory seized from Georgia and over the Russian province Kaliningrad, which is separate from the rest of Russia and sandwiched between Poland and Lithuania. In response, the U.S. had limited flights over some sensitive areas in Hawaii and Alaska.
"What [Russia] has been saying is, 'Yes, you can fly anywhere you want and look at anything you like at any time, except for the things we don't wish you to see,' and that kind of selective limitation clearly cuts at the heart of the confidence-building that is the purpose of the Open Skies Treaty," said Assistant Secretary of State for International Security and Non-proliferation Christopher Ford. Russia "has had no accountability for that, and we are now finally providing that kind of accountability."
Advocates of the pact point out that Russia recently approved of a joint flight by the U.S., Estonia, and Latvia over Kaliningrad earlier this year without those restrictions. Ambassador Jim Gilmore, Trump's envoy to the Organization for Security and Cooperation in Europe, also said in March that Russia will no longer raise an "objection" for flights "over one of their major exercises."
While Ford dismissed those developments as not representative of Russia's view it can "turn its obligations on and off like a light switch," experts say it's proof that the U.S. can negotiate with Moscow for improvements.
"These problems can and should be solved through professional, pragmatic diplomacy, not by abandoning treaty commitments," wrote President Ronald Reagan's long-time Secretary of State George Shultz, along with President Bill Clinton's Defense Secretary William Perry and former Democratic Sen. Sam Nunn, in a letter to Trump in March.
Trump's first Defense Secretary James Mattis backed that view during his time as Pentagon chief, calling it "an important mechanism for engaging with our allies and partners" that "contributes to greater transparency and stability." In particular, he noted, it was critical to exposing Russia's military presence in eastern Ukraine in 2014, even as Moscow denied playing a role in the fighting there.
Republican lawmakers, however, have backed Trump's decision, arguing that Russia gained more out of the pact while the U.S. can continue its surveillance through a network of advanced satellites.
"In terms of intelligence collection, Moscow needs the Open Skies treaty more than Washington, yet Moscow has refused to abide by the treaty's obligations," said Bradley Bowman, a former national security adviser to Senate Republicans who's now at the Foundation for Defense of Democracies think tank.
But data compiled by researchers at the Institute for Peace Research and Security Policy in Germany shows the U.S. receives far fewer flights over its territory than it and its allies fly over Russia's. Some analysts also say Russia's surveillance capability outside the flights is advanced enough that they don't need them as much as U.S. officials believe -- but when they collect that information on their own, they aren't required to share it with the U.S. or other signatories.
Advocates of the treaty also say its purpose is beyond collecting intelligence, but also about creating stability and collective security through transparency -- and by allowing Russian officials on board with Americans and other Europeans. That builds a "normalizing, collegial routine which builds trust," according to Melissa Hanham, deputy director of the Open Nuclear Network.
The administration also appears to have disregarded the law by failing to notify Congress of its intent to withdraw 120 days in advance of the formal notification. That could spark a new legal battle down the road, as the Senate has to approve by a two-thirds majority of any treaty's ratification -- and, some Democrats have recently argued, its withdrawal.
"Congress's role over treaty withdrawal has remained uncertain for far too long. Our founders intended that no U.S. president should have full control of treaty powers," said Sen. Ed Markey, D-Mass., Thursday, proposing new legislation to require Senate approval for any treaty withdrawal or ratification.
Arms control advocates also fear what U.S. withdrawal from the Open Skies Treaty means for the last piece of nuclear arms control between the U.S. and Russia, New START, or Strategic Arms Reduction Treaty. It expires next February, and while the two sides have engaged in some talks, the Trump administration has indicated it does not want to extend the pact unless it involves China -- a proposition China has rejected.
Billingslea announced Thursday that he and his Russian counterpart, Deputy Foreign Minister Sergei Ryabkov, are finalizing plans to begin negotiations as soon as possible. While he said their "expectation is that the Chinese will likewise be at the table," he gave no indication that they have had steps toward that goal, saying instead, "The Chinese have an obligation to negotiate with us in good faith."