US President Joe Biden has approved the deployment of an extra 3,000 additional troops to Eastern Europe, as Washington tries to reassure Nato partners of its full support in tackling the Ukraine crisis.
Pentagon spokesman John Kirby said on Wednesday that the troops would not go into Ukraine, but would be used to shore up Nato's eastern flank. About 2,000 will be sent from the US, with another 1,000 troops sent from US bases in Germany to Romania.
"We are making it clear that we're going to be prepared to defend our Nato allies if it comes to that," Mr Kirby said.
The troops are in addition to 8,500 the Pentagon recently placed on standby.
The Ukraine crisis unfolded when Russian President Vladimir Putin last year amassed more than 100,000 troops along the lengthy border with Ukraine.
Moscow insists it is not planning to invade and has blasted the West's response, saying the US and Nato are being aggressive towards Russia.
"Conflict is not inevitable," Mr Kirby said, noting that the US still does not know if Mr Putin has made a decision to invade.
White House Press Secretary Jen Psaki said the troop deployment was aimed at providing reassurance and readiness to partners in the region.
"If President Putin and the Russians decide to de-escalate that would be a welcome step," she said.
Ms Psaki said the decision to send additional troops was not based on any developments over the past 48 hours.
"This is the United States abiding by our commitments under Article Five to support and reassure our partners in the region," she said, referring to Nato's mutual self-defence clause.
The West has for weeks warned of severe sanctions and financial repercussions for Russia if it does attack.
Russia, which seized Crimea from Ukraine in 2014 and backs pro-Russian rebels fighting government forces in eastern Ukraine, is demanding sweeping security guarantees including a promise that Nato never admit Ukraine.
The US has dismissed such calls, saying it would be up to Ukraine and Nato whether Kiev ever joins the alliance.
"It's not something that Mr Putin gets to have a veto on. It doesn't work like that," Mr Kirby said on Tuesday.
The US already has between 75,000 and 80,000 troops in Europe as permanently stationed forces and as part of regular rotations in places such as Poland.
Russia condemned the Biden administration’s decision, calling it an unjustified step in the crisis.
Russian Deputy Foreign Minister Alexander Grushko said the deployment of US troops to Europe was a destructive move that would delight the Ukrainian authorities. He accused Kiev of trying to sabotage the Minsk agreement "with impunity".
In signs that, publicly at least, Russia is in no mood to signal compromise, the Kremlin mocked the beleaguered British Prime Minister Boris Johnson as "utterly confused" and ridiculed UK politicians for their "stupidity and ignorance".
Britain's Royal Air Force on Wednesday scrambled fighters to intercept four Russian Tupolev bombers that were approaching the UK.
The jets escorted the Russian bombers, which have a range of 8,000 kilometres, out of Britain's area of interest, the RAF said.
French President Emmanuel Macron, meanwhile, said the Ukraine crisis has reached a decisive moment that was “threatening our collective security”.
His remarks come as he refuses to confirm whether he will seek re-election in April.
He said the severity of the Ukraine crisis meant the public would expect him to focus on this before he turns his attention to his own electoral prospects.
“The hours we are living through are decisive ones for the security of the whole region,” he told the newspaper La Voix Du Nord. “As long as dialogue is there, we have to keep it going.”
France, like its neighbour Germany, has focused on dialogue as a way of resolving the stand-off, and the US has extended several diplomatic olive branches to Russia.
A Spanish newspaper on Wednesday reported that the US could be willing to enter into an agreement with Russia to ease tensions over missile deployments in Europe if Moscow steps back from the brink.
The two documents published by Spanish newspaper El Pais reveal the formal response by America and its allies to Russia’s demands for two new security treaties in Europe.
They reject the Kremlin’s central demand to veto any further eastward expansion of Nato, and say Russia must pull back troops for any meaningful progress to be made.
But they suggest potential areas of agreement, such as refraining from stationing troops or missile launchers in Ukraine, limiting intermediate and short-range missiles and lowering the threshold at which the US and Nato would be required to alert Moscow to drills.
Agencies contributed to this report.
Joe Biden: 'I may move troops to Eastern Europe in near term'
