The US is pulling out of a nuclear arms treaty with Russia that has been in place since towards the end of the Cold War, secretary of state Mike Pompeo has announced.
The move from the Trump administration had been rumoured in recent months and was confirmed on Friday.
It follows years of unresolved dispute over Russian compliance with the 1987 document which bans certain ground-launched cruise missiles.
However, Russia denies violating the treaty which bans either side from stationing short and intermediate-range land-based missiles in Europe
Mr Pompeo said the US will suspend its obligations to the treaty on Saturday and that if Russia does not come into compliance with it the treaty "will terminate".
The US-Russia Intermediate-Range Nuclear Forces Treaty has been a centerpiece of superpower arms control since the Cold War.
It 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.
Secretary of State Mike Pompeo said in early December that Washington would give Moscow 60 days to return to compliance to the treaty efore it gave formal notice of withdrawal.
That would then take place six months later.
The 60-day deadline expires on Saturday.
Iin talks this week in Beijing, the US and Russia reported no breakthrough in their dispute.
This left little reason to think either side would change its stance on whether a Russian cruise missile violates the pact.
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NATO allies "fully support" the United States' pending withdrawal notice from the INF nuclear missile pact over alleged breaches by Russia, a statement by the alliance said.
This said: "The United States is taking this action in response to the significant risks to Euro-Atlantic security posed by Russia's covert testing, production, and fielding of 9M729 ground-launched cruise missile systems.
"Allies fully support this action."