Biden, Putin discuss Ukraine, NATO issues

US President Joe Biden has warned Russian leader Vladimir Putin the West would impose "strong economic and other measures" on Russia if it invades Ukraine, while Putin demanded guarantees NATO would not expand further eastwards.

The two leaders held two hours of virtual talks on Ukraine and other disputes in a video call about US-Russian relations, which have sunk to their lowest point since the end of the Cold War more than three decades ago.

The Kremlin, which said before Tuesday's meeting it did not expect any breakthrough, has denied harbouring any intention to attack Ukraine and has said its troop posture is defensive.

US officials said before the video conference Biden would tell Putin Russia and its banks could be hit with the toughest sanctions yet if it attacks Ukraine.

"Things we did not do in 2014 we are prepared to do now," US National Security Adviser Jake Sullivan told reporters after the call, referring to Russia's annexation of Crimea from Ukraine seven years ago.

Biden was "direct and straightforward" with Putin, Sullivan said, telling the Russian leader the United States and European allies would provide additional defensive capabilities to Ukraine, as well as beef up NATO allies in the region.

"There was a lot of give and take, there was no finger-wagging, but the president was crystal clear where the United States stands on all of these issues," Sullivan said.

The Kremlin said Putin told Biden it was wrong to put all the responsibility on Russia's shoulders for current tensions.

Moscow has voiced rising irritation over Western military aid to Ukraine, a fellow former Soviet republic that has tilted towards the West since a popular revolt toppled a pro-Russian president in 2014, and what it calls creeping NATO expansion.

The Kremlin said Putin told Biden he wanted reliable, legally binding guarantees against NATO expansion further eastwards and complained about NATO attempts to "develop" Ukrainian territory.

Putin also called for guarantees that offensive strike systems would not be deployed in countries close to Russia, according to the Kremlin.

Both sides agreed to continue contacts, with hopes for an in-person summit, and directed their teams to consult on questions about Ukraine.

A Ukraine official said after the talks Kiev was grateful to Biden for his "unwavering support".

Washington has accused Russia of massing troops near the border with Ukraine to intimidate an aspiring NATO member, suggesting it could be a repeat of Moscow's 2014 playbook, when it seized the Black Sea peninsula of Crimea from Ukraine.

Moscow has questioned Ukrainian intentions and said it wants guarantees that Kiev will not use force to try to retake territory lost in 2014 to Russia-backed separatists, a scenario Ukraine has ruled out.

For the Kremlin, the growing NATO embrace of neighbouring Ukraine - and what it sees as the nightmare possibility of alliance missiles in Ukraine targeted against Russia - is a "red line" it will not allow to be crossed.

Leaders from Britain, the United States, France, Germany and Italy spoke on Monday and "agreed to stay in close touch on a co-ordinated and comprehensive approach in response to Russia's military build-up on Ukraine's borders", the White House said.