Nuclear 'Armageddon' threat back for first time since Cold War, says Biden

US President Joe Biden said Thursday the world risks nuclear "Armageddon" for the first time since the Cold War.

US President Joe Biden said Thursday the world risks nuclear "Armageddon" for the first time since the Cold War and that he is trying to find Russian President Vladimir Putin's "off-ramp" in the Ukraine conflict.

"We have not faced the prospect of Armageddon since Kennedy and the Cuban missile crisis" in 1962, Biden said at a Democratic party fundraising event in New York.

Putin is "not joking" when he threatens to use nuclear weapons to pursue his invasion of Ukraine, Biden said.

Biden made his unusually strong comments about the risks created by Putin's nuclear threats while speaking to party supporters at an event hosted in the Manhattan home of James Murdoch, son of newspaper mogul Rupert Murdoch.

Referring to the nuclear standoff triggered by the Soviet Union stationing missiles in Cuba, within easy range of the United States, Biden said that for the "first time since the Cuban missile crisis, we have a direct threat from the use of nuclear weapons if in fact things continue down the path they are going."

Putin has made thinly veiled threats to use nuclear weapons if he feels he has run out of options in his bid to seize swaths of Ukrainian territory in the face of stiff resistance by Western-back Kyiv.

Experts say these would most likely be relatively small, tactical strikes. But Biden warned that a tactical strike in a limited area would still risk triggering a wider conflagration.