The accord is the last arms control agreement between the former Cold War rivals but negotiations to extend it had faltered under Biden's predecessor Donald Trump.

"We can only welcome the political will to extend this document," Kremlin spokesman Dmitry Peskov told reporters.

Peskov added however that any decision to extend the pact would depend on "the details of the proposal" from Washington. He said Moscow needed more time to study the US administration's offer.

White House press secretary Jen Psaki told reporters Thursday that the US would lobby for a five-year extension to the pact.

She said the extension was needed now more than ever given "adversarial" ties between Russia and the United States.

Peskov noted that previous conditions for the extension of the accord put forward by the United States "absolutely did not suit us".

The accord restricts the former Cold War rivals to a maximum of 1,550 deployed warheads each, a cut of about 30 percent from a limit set in 2002, and 800 launchers and bombers -- enough to blow up the world many times over.

Talks last year stalled over Trump's insistence that China also become a party to the agreement, even though Beijing said it would not participate.

Russian President Vladimir Putin himself had offered Trump a five-year extension, the maximum allowed under the treaty that was signed in 2010 in Prague by former president Barack Obama.