US president Joe Biden has said he is now convinced that Russian leader Vladimir Putin has made a decision to attack Ukraine.
Speaking at the White House in Washington on Friday he suggested that an invasion – including an attack on the Ukrainian capital Kyiv – could take place “in the coming week, in the coming days”.
Mr Biden said the crisis in Ukraine was rapidly escalating.
For the first time the US president said he was “convinced” that Mr Putin had decided on an invasion of Ukraine. For several weeks US authorities had maintained it was unsure whether Mr Putin had made the final decision to attack. However, the president on Friday indicated that this assessment had now changed.
“As of this moment, I’m convinced he’s made the decision,” Mr Biden said.
“We have reason to believe that.”
He said the US had “reason to believe” the attack would occur in the “coming week, the coming days” and would target the Ukrainian capital, Kyiv, which he said was a city of 2.8 million innocent people.
He cited the United States’ “significant intelligence capability” for the assessment.
"We're calling out Russia's plans loudly [and] repeatedly, not because we want a conflict but because we're doing everything in our power to remove any reason that Russia may give to justify invading Ukraine and prevent them from moving."
The US president said Russia was setting out false justifications for an attack on Ukraine.
Mr Biden warned the US and its allies were ready to impose “massive costs” on Russia should it opt to invade.
"The American people are united. Europe is united. The transatlantic community is united. The entire free world is united."
He said if Russia pursued the plans to attack it would be “responsible for a catastrophic and needless war of choice”.
Mr Biden said Russia had a choice “between war and all the suffering that it will bring or diplomacy that will make the future safer for everyone”.
“We’re ready to impose severe sanctions on Russia if it further invades Ukraine. But I say again, Russia can still choose diplomacy. It is not too late to de-escalate and return to the negotiating table.”
Mr Biden said the US and its allies were "determined to defend every inch of Nato territory from any threat to our collective security".
He said the US would not send troops to fight in Ukraine but would support the Ukrainian people.
He said he believed that Mr Putin was not remotely contemplating using nuclear weapons (in any attack on Ukraine).