ITV News Senior International Correspondent John Irvine has the latest developments on the extensive build up of Russian troops near Ukraine's border which has prompted fears of an invasion
Russia faces "disaster" if it invades Ukraine, Boris Johnson has said, just hours after US President Joe Biden warned Vladimir Putin that his country will pay a "stiff price" if it does, threatening a possible cut-off from the global banking system.
Russia has reportedly massed 100,000 troops near the Ukrainian border and a series of talks held in Europe last week failed to ease tensions.
Speaking during a visit to a diagnostics centre in Taunton, the prime minister reiterated the UK’s support for Ukrainian sovereignty.
“If Russia were to make any kind of incursion into Ukraine on any scale whatever, I think that would be a disaster not just for Russia, it would be a disaster for the world,” he said.
“The UK stands squarely behind the sovereignty and integrity of Ukraine.”
The build up of troops on the Ukrainian border has led to fears amongst the international community that Russia is looking to invade its neighbour, leading to war in the region.
Speaking on Wednesday night to mark one year since he took office, Mr Biden said he believes that Russia is preparing to take action on Ukraine - though he does not think Mr Putin has made a final decision.
The US president said: “I’m not so sure that he is certain what is he going to do... My guess is he will move in.”
"They’ll pay a stiff price immediately, near-term, medium term and long-term if they do it," he added.
Mr Biden also suggested that he would limit Russia’s access to the international banking system if it did further invade Ukraine.
“If they actually do what they’re capable of doing with the force of masse on the border it's going to be a disaster for Russia," he continued.
"Our allies and partners are ready to impose severe cost and significant harm on Russia and the Russian economy."
Mr Biden’s comments came hours after US Secretary of State Antony Blinken, during a visit to Kyiv, accused Russia of planning to reinforce the troops it has deployed along the Ukrainian border and suggested that number could double “on relatively short order.”
Mr Blinken did not elaborate, but Russia has sent an unspecified number of troops from the country’s far east to its ally Belarus, which also shares a border with Ukraine, for major war games next month.
Ukraine said it was prepared for the worst and would survive whatever difficulties come its way. The president urged the country not to panic.
Mr Biden and the White House also moved quickly to clarify his comments, saying that a “minor incursion” of Ukraine would elicit a lesser response than a full-scale invasion of the neighbouring country.
A "minor" incursion would still be a concerning breach of Ukraine's borders, the White House clarified.
It made clear that Mr Biden was not suggesting to Mr Putin that the US would tolerate military action against Ukraine.
The president said he was referring to non-military action such as a cyberattack but his Office warned such action would be met with a similar reciprocal response, and that if Russian forces cross the Ukrainian border, killing Ukrainian fighters, “that changes everything.”
The comments also hinted, however, at the challenge of keeping the US and its NATO allies united in their response to Russia.
In explaining the minor incursion remark, he said “it’s very important that we keep everyone in NATO on the same page."
The US president said he believes the decision will “solely” be Mr Putin’s and suggested he was not fully confident that Russian officials with whom top White House advisers have been negotiating are fully informed about Mr Putin’s thinking.
“There’s a question of whether the people they’re talking to know what he’s going to do,” Mr Biden said.
On Wednesday, Armed Forces minister James Heappey warned intelligence indicates "something catastrophic" lies ahead and said the Ukrainians are “ready to fight for every inch of their country”.
Mr Heappey told ITV News: "What I see… is intelligence that suggests that we are on the brink of something quite catastrophic in Ukraine – and that will have national security and economic consequences for the UK."
Mr Blinken’s visit to the Ukrainian capital comes two days before he is to meet in Geneva with Russian Foreign Minister Sergey Lavrov. That follows a series of inconclusive talks last week that failed to ease rising tensions.
Russian military activity has been increasing in recent weeks, but the US has not concluded whether Mr Putin plans to invade or whether the show of force is intended to squeeze the security concessions without an actual conflict.
Russia in 2014 seized the Crimean Peninsula after the ouster of Ukraine’s Moscow-friendly leader and also threw its weight behind a separatist insurgency in eastern Ukraine.
More than 14,000 people have been killed in nearly eight years of fighting between the Russia-backed rebels and Ukrainian forces in the country’s industrial heartland, called Donbas.