An armored personnel carrier is seen during tactical exercises in the abandoned city of Pripyat near the Chernobyl Nuclear Power Plant, Ukraine, February 4, 2022. (Photo by Reuters)

US national security adviser Jake Sullivan has warned that Russia could invade Ukraine any day now, escalating the rhetoric days after the White House said it was no longer describing a potential Russian attack as imminent.

We are in the window, Sullivan said in an interview on the Fox News Sunday program. Any day now, Russia could take military action against Ukraine or it could be a couple of weeks from now, or Russia could choose to take the diplomatic path instead.

The comments came after two US officials said on Saturday that Russia has deployed about 70 percent of the military capability it would need to launch a full-scale invasion of Ukraine.

Sullivan appeared on several talk shows on Sunday to discuss the ongoing situation around Ukraine.

Any possible Russian action, he said on NBC�s Meet the Press, could take different forms, including annexing the eastern Donbass region, where conflict erupted between pro-Russia separatists and Ukrainian government forces in 2014, or a full-scale invasion of Ukraine.

Part of the reason we�ve been working so intensively over the last few months is not just to prepare for one contingency but to prepare for all contingencies and to work with our allies and partners on what a response would look like in each of those instances, Sullivan said.

The official alleged that Russia could move in against Ukraine as soon as on Monday, without saying where the intelligence was coming from.

We believe that 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, Sullivan said.

The US and its allies accuse Russia of preparing for an invasion of Ukraine by amassing thousands of troops and armaments near the border with that country. Russia has denied this and said the troop build-up is defensive and in response to NATO�s eastward expansion and increased activity near Russian borders.

Moscow, however, has threatened to take unspecified measures if its security demands are not met. Those include assurances that NATO will never admit Ukraine, a demand the United States and the military alliance have called unacceptable.

It has also called on NATO to roll back its military deployments in Central and Eastern Europe, saying the expansion poses a serious threat to Russia.

Since Friday, the United States has begun deploying new reinforcement troops to Eastern Europe to reinforce NATO allies

The Kremlin has blamed troop deployments near Russia and the bellicose rhetoric coming out of Washington and the European capitals for the spiraling tensions.

It is these statements, the deployment of troops near our borders and daily activities to pump Ukraine with weapons that lead to these tensions, Kremlin spokesman Dmitry Peskov told TASS on Saturday.