Biden “has been clear for months now that the United States is not sending forces to start a war or fight a war with Russia in Ukraine,” White House national security advisor Jake Sullivan told Fox News on Sunday, adding that “we have sent forces to Europe to defend NATO territory.”

Biden has ordered the deployment of several thousand US troops to NATO member countries in the region to bolster NATO’s eastern flank and as a show of support for the alliance.

In an appearance on NBC’s “Meet the Press” on Sunday, Sullivan said “a military escalation and invasion of Ukraine could happen at any time.” He added that the US believes “the Russians have put in place the capabilities to mount a significant military operation into Ukraine, and we have been working hard to prepare a response.”

Although it is concerned, the US has also said that it remains unclear whether or not Putin has made a decision to invade Ukraine.