Biden, Putin to speak as US warns of imminent Russian invasion

President Biden and Russian President Vladimir Putin are slated to speak on Saturday morning, a White House official confirmed, as the U.S. warns of an immediate threat of a possible Russian military invasion of Ukraine.

The official said that the Russians proposed a call on Monday and the U.S. counter-proposed a call on Saturday, which the Russians accepted.

White House national security adviser Jake Sullivan told reporters earlier Friday that the two leaders were likely to speak, but did not offer a specific time frame.

"I would expect that President Biden will engage by telephone with President Putin, but I don't have anything to announce for you on that right now," Sullivan told reporters during a briefing Friday afternoon.

The call will be the first between the two leaders in over a month, and comes as the U.S. escalates warnings about Russia's buildup of more than 100,000 troops on the border with Ukraine.

In a sobering update, Sullivan said that Russia had amassed enough forces on the border with Ukraine to launch a "major military action against Ukraine" and said it could happen at any time, including during the Olympics.

There had been speculation that Putin would hold off on invading Ukraine during the Winter Olympic Games in Beijing, which are due to end on Feb. 20.

A handful of foreign leaders have engaged with Putin in recent days in efforts to ward off a Russian invasion of Ukraine, including French President Emmanuel Macron, who met with Putin earlier this week.

Sullivan told reporters Friday that the U.S. still does not believe that Putin has made up his mind on invading Ukraine.

Still, he urged Americans in Ukraine to leave immediately, within the next 24 to 48 hours, and said the U.S. is working to shrink its footprint at the embassy in Kiev.

Earlier Friday, Biden held a secure video call with the leaders of Canada, Germany, France, the United Kingdom, Poland, Italy and Romania about the Russian military buildup on Ukraine's border.

Biden, who last spoke with Putin at the end of December, is slated to spend the weekend at Camp David.

White House press secretary Jen Psaki noted that the presidential retreat is "fully equipped" for Biden to engage with his national security team as well as European counterparts.

Biden has warned Putin that Russia would face severe economic consequences if Russia were to invade Ukraine, in the form of global sanctions.

The Pentagon on Friday announced plans to send an additional 3,000 troops to Poland, on top of 3,000 already sent to NATO allies in recent weeks to ward off a Russian threat.

This story was updated at 4:33 p.m.