President Biden said Wednesday that his "guess" is that Russian President Putin will invade Ukraine.
Biden said that he feels that Putin "has to do something."
Russia has been massing tens of thousands of troops along Ukraine's border over the past several weeks.
President Joe Biden, who has had talks directly with Russian President Vladimir Putin to discuss the Russian troop build-up that's threatening Ukraine, said it's his guess that Putin "will move in."
"I think he still does not want any full-blown war," Biden said during a press briefing Wednesday. "Do I think he'll test the west? Test the United States and NATO as significantly as he can? Yes I think he will."
Biden warned that Russia would be held accountable if it invades but the reaction from the United States would depend on the nature of such an invasion.
"It's one thing if it's a minor incursion and we end up having to fight about what to do and not do," Biden said. He warned that a full-scale invasion of Ukraine would be "a disaster for Russia."
Biden said he believes Putin is not sure yet what he will do. The president said he told Putin that they could "work out something" on keeping nuclear weapons out of Ukraine but that barring Ukraine from NATO is not possible because of existing treaties throughout Europe.
Biden's comments on Wednesday echoed what's been said by the White House and Secretary of State Antony Blinken in recent days. During a visit to Kyiv on Wednesday, Blinken warned that Russia could attack Ukraine on "very short notice."
Russia claims it has no plans to invade, but has rejected calls from Western leaders for it to pull its troops away from Ukraine's border. Moreover, Russia invaded and annexed Crimea from Ukraine in 2014, and has since supported rebels in a war against Ukrainian forces in the eastern Donbass region.
The Biden administration has warned of severe economic consequences if Russia invades Ukraine. Biden on Wednesday said that Russia's banks wouldn't be able to deal in dollars in the event of an invasion. Senate Democrats also recently introduced legislation that would see Putin directly targeted with sanctions if Russia invades.
The president said Putin has "never seen sanctions like the ones I promised to impose if he moves" on Ukraine.