President Donald Trump announced Thursday he plans to withdraw the United States from the Open Skies Treaty with Russia, the third arms control pact Trump has abrogated since coming to office.
The US leader said Moscow had not stuck to its commitments under the 18-year-old pact, which was designed to improve military transparency and confidence between the superpowers.
"Russia did not adhere to the treaty," Trump told reporters at the White House.
"So until they adhere, we will pull out."
Moscow quickly countered that the pullout would damage European security and harm the interests of US allies.
Ambassadors to NATO, whose members are also party to the treaty, called an urgent meeting Friday to assess the consequences of the move, which could impact European security.
Germany's Foreign Minister Heiko Maas urged Washington to reconsider, saying that Germany, France, Poland and Britain had repeatedly explained to the US that the problems with the Russians in recent years "did not justify" pulling out.
The treaty "contributes to security and peace in almost all of the northern hemisphere," Maas said.
"We will continue implementing the treaty and do everything to preserve it."
US Secretary of State Mike Pompeo said Trump would formally notify the parties to the treaty on Friday of US plans to withdraw, which will start a six-month countdown to pullout.
"Effective six months from tomorrow, the United States will no longer be a party to the Treaty," Pompeo said in a statement.
"We may, however, reconsider our withdrawal should Russia return to full compliance with the Treaty."
The Open Skies agreement permits each signatory country's military to conduct a certain number of surveillance flights over another member country each year on short notice.
The aircraft can survey the territory below, collecting information and pictures of military installations and activities.
Including Russia and the United States, the treaty has 35 signatories, though one, Kyrgyzstan, has not yet ratified it.
The idea is that the more rival militaries know about each other, the smaller the chance of conflict.
But the flights are also used to examine vulnerabilities of the other side.
Pentagon spokesman Jonathan Hoffman said Russia "flagrantly, continuously violates its obligations" under the pact.
Moscow "implements the treaty in ways that contribute to military threats against the United States and our allies and partners," he said.
He cited Russia's refusal to allow flights over areas where Washington believes Moscow is deploying medium-range nuclear weapons that threaten Europe, including the Baltic Sea city of Kaliningrad and near the Russia-Georgia border.
Last year Moscow also blocked flights meant to survey Russian military exercises, normally allowed under the pact.
The New York Times said Trump was also unhappy about a Russian flight over his golf resort in Bedminster, New Jersey three years ago.
"In this era of great power competition, we are looking to advocate for agreements that benefit all sides, and that include partners who comply responsibly with their obligations," Hoffman said.
It will be the third important arms control pact that Trump has withdrawn from since coming to office in January 2017.
He has also dropped the 2015 JCPOA agreement to prevent Iran from advancing its nuclear weapons program, and the 1988 Intermediate Range Nuclear Forces Treaty with Russia.
In both cases Trump accused the other side of violating treaty requirements.
It also added to the question marks over another pact, the New START which limits the number of nuclear missiles the United States and Russia can deploy, and needs to be renewed by early 2021.
US officials said the Trump administration had studied the issue for eight months and canvassed allies' opinions before reaching the decision to withdraw from Open Skies.
By its actions, "Russia has systematically destroyed conventional arms control in Europe," said Marshall Billingslea, Trump's special envoy for arms control.
Benjamin Friedman of the liberal Defense Priorities think tank said the move would only accelerate competition between world powers.
"The Open Skies Treaty is not particularly important to US security, but it does build trust worth preserving," he said in a statement.
"Along with the US exit from other major arms control treaties, this move reveals a disconcerting pattern of pointless hostility to treaties which will make future accords more difficult to negotiate."