Biden warns Putin ‘not joking’ about nuclear threat

US president Joe Biden warned the risk of nuclear “Armageddon” was at its highest since the Cuban missile crisis in 1962 and said he was trying to figure out what Vladimir Putin’s “off-ramp” might be to avoid further escalation.

Speaking at a fundraiser in New York on Thursday night, Biden said Russia’s president was “not joking” when he spoke about the “potential use of tactical nuclear weapons or biological or chemical weapons because his military is you might say significantly underperforming”.

“We have not faced the prospect of Armageddon since Kennedy and the Cuban missile crisis,” Biden said, adding that “we have a direct threat of the use of nuclear weapons if in fact things continue down the path they are going”.

He said he was trying to understand if there was a way for Putin to back down. “I’m trying to figure out: what is Putin’s off ramp?” Biden said. “Where does he find a way out?”

Biden’s comments, at the home of James Murdoch, the media investor, reflect mounting anxiety in Washington and across Europe that Russia might be preparing to use nuclear weapons in the Ukraine war. In recent weeks, Putin has adopted increasingly blustery rhetoric, and escalated the conflict by moving to annex entire regions of southern and eastern Ukraine even as the Russian military has faced significant setbacks in those areas.

Senior US officials have warned Russia would face “catastrophic consequences” if Moscow used nuclear weapons and said they had communicated what those would be in private to Russian officials. However, the US has not explained in public how it would respond to the use of weapons of mass destruction by Moscow.

Biden’s reference to the search for an “off-ramp” for Putin suggests the US and allies are still trying to determine whether Russia’s leader could be made to step back from the brink — even though they insist decisions about Ukraine’s future would have to agreed by Kyiv.