The US is pulling out of a treaty with Russia which has been a centrepiece of arms control since the Cold War.
The withdrawal had been expected for months, and follows years of unresolved dispute over Russian compliance with the 1987 pact, which bans certain ground-launched cruise missiles.
Russia denies violating the treaty, but US secretary of state Mike Pompeo said Washington will suspend its obligations to the pact on Saturday and if Moscow does not come into compliance, it “will terminate”.
US officials have also expressed concern that China, which is not part of the treaty, is deploying large numbers of missiles in Asia that the US cannot counter because it is bound by the treaty.
The Intermediate-Range Nuclear Forces, or INF, treaty was the first arms control measure to ban an entire class of weapons: ground-launched cruise missiles with a range between 310 and 3,100 miles.