The Biden administration on Thursday reiterated its warnings to Russia over a potential invasion of Ukraine, with one senior administration official telling reporters that the US is "ready to act if and when we need to," CNN reported.

"We have been clear that there will be significant consequences" if Russia attacks, the official said. The penalties would be coordinated closely with US allies and partners and would severely damage Russia's economy, the official said. Such a move would also result in NATO capabilities being moved closer to Russia.

Speaking just hours after Putin's marathon year-end news conference, in which he said Russia's actions will depend on the US's and NATO's "unconditional ensuring of Russia's security today and in the future," the US official said the Biden administration is prepared to discuss some of Russia's concerns.

But the official said Russia has made some demands "that they know we can never agree to." And in an apparent rebuke of Russian officials' insistence in recent days that it would engage only in bilateral talks with the US, the official said any dialogue "must also take place in full coordination with our allies."

Still, the official said, "the Biden administration is willing to engage with Russia through multiple channels as soon as early January." A date and time for the discussions has not been set yet.

Separately, White House press secretary Jen Psaki stated: "Well, facts are a funny thing, and facts make clear that the only aggression we're seeing at the border of Russia and Ukraine is the military buildup by the Russians and the bellicose rhetoric from the leader of Russia."

Psaki added that NATO "is a defensive alliance, not an aggressive alliance. There is no evidence to the contrary, to suggest anything to the contrary, from the United States or NATO members, and of course our efforts are to work with and defend our NATO partners."