Boris Johnson will have further talks with Joe Biden on Tuesday night as Western allies consider how to respond to the situation in Ukraine.
The US president will update the Prime Minister and other European powers on the latest developments after his talks with Russian leader Vladimir Putin.
It will be the second call in 24 hours between Mr Johnson, Mr Biden, Italian prime minister Mario Draghi, French president Emmanuel Macron and German chancellor Angela Merkel as they seek to present a united front in response to the threat of a Russian incursion into Ukraine.
In a call on Monday, Mr Johnson told his fellow leaders “the UK would continue to use all the economic and diplomatic tools at its disposal to prevent any Russian aggression against Ukraine”.
In the Commons on Tuesday, Foreign Office minister Vicky Ford told MPs that the UK was considering “an extension of purely defensive support to Ukraine to help Ukraine defend itself”.
She said any “military incursion” by Russia into the Eastern European country would be a “strategic mistake”.
Mr Biden was expected to use his call with Mr Putin to warn the US would impose serious economic sanctions if Russian forces crossed into Ukraine.
“We’ve consulted significantly with our allies and believe we have a path forward that would impose significant and severe harm on the Russian economy,” White House press secretary Jen Psaki said in a preview of the video call.