US President Joe Biden said he had warned his Russian counterpart Vladimir Putin of unprecedented US sanctions if his country invades Ukraine.

A day after talking for two hours by video link, Biden told reporters at the White House the United States and its allies would impose large-scale economic sanctions on Russia should it invade Ukraine, hinting at efforts to halt the Nord Stream 2 pipeline.

The US already collaborates closely with the Ukrainian military and has provided millions of dollars in weaponry. However, Biden made it clear that sending US troops to confront Russia was "not on the table."

Biden said the United States would provide additional defense aid to Kyiv beyond what it currently provides, not to mention that the United States would also provide support to NATO allies in the Alliance's eastern flank.

"The idea the United States is going to unilaterally use force to confront Russia invading Ukraine is not on the cards right now," Biden stressed. "We have a moral obligation and a legal obligation to our NATO allies under Article Five. It's a sacred obligation. That obligation does not extend to... Ukraine."

Putin got "the message," Biden concluded.

Talks were "frank"

Kremlin described the talks as "frank" and said the Russian president requested Washington to provide guarantees NATO would not continue its eastward expansion.

"Russia is seriously interested in obtaining reliable legal guarantees that will exclude NATO's eastward expansion and the deployment of offensive strike weapons in countries adjacent to Russia," the statement mentioned.

According to the Kremlin, Putin proposed to his US counterpart Joe Biden that Moscow and Washington lift all restrictions on embassy staff in both countries.

Kremlin aide Yury Ushakov told reporters Putin informed his US counterpart Biden of Ukraine's failure to comply with the Minsk agreements.

“Our president informed [Biden] in sufficient detail about how Kyiv fails to fulfill the relevant Minsk agreements. It was said directly that Ukraine sabotages the Minsk implementation. In addition, it sabotages the agreements reached within the framework of the Normandy Four summit, delays the negotiation process in the contact group, and seeks to exclude Donbas from the negotiation process," Ushakov said following the leaders' talks.

This is the fifth conversation between Putin and Biden since the latter took office.