NEW YORK - US President Joe Biden said on 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, Mr Biden said at a Democratic party fundraising event in New York.  

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

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

Referring to the nuclear standoff 60 years ago triggered by the Soviet Union stationing missiles in Cuba, within easy range of the United States, Mr 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”.

“We’re trying to figure out what is Putin’s off-ramp,” he said.

Mr 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 Mr Biden warned that a tactical strike in a limited area would still risk triggering a wider conflagration.  

“We’ve got a guy I know fairly well,” Mr Biden said. 

Mr Putin’s “not joking when he talks about potential use of tactical nuclear weapons or biological or chemical weapons, because his military is, you might say, significantly underperforming".

However, “I don’t think there’s any such thing as the ability to easily (use) a tactical nuclear weapon and not end up with Armageddon", Mr Biden said.  

“I’m trying to figure out what is Putin’s off-ramp,” Mr Biden said. “Where does he find a way out? Where does he find himself in a position that he does not, not only lose face, but lose significant power within Russia?”

The White House said, however, on Friday that the United States sees no reason to change its nuclear posture and does not have indications that Russia is preparing to imminently use nuclear weapons.

“He was reinforcing what we have been saying, which is how seriously... we take these threats” from Russia, White House spokesman Karine Jean-Pierre told reporters on Air Force One when asked about Mr Biden’s comments.

Still, Mr Biden's comments are in contrast to those from National Security Adviser Jake Sullivan, who said last week that the US sees Russia's threat to use nuclear weapons as the latest in a string of similar warnings Mr Putin has employed since the invasion began in February.

"We do not presently see indications about the imminent use of nuclear weapons," Mr Sullivan said. "We are, of course, monitoring that carefully and staying in close consultation with allies and partners."

Still, Mr Sullivan said, the US has clearly conveyed that there would be severe consequences if Russia uses nuclear weapons, and continues to take the threat seriously.

Mr Biden in recent weeks has been hitting the road to promote recent Democratic legislative victories and to raise money for the party, including fundraisers in New York last month when he was there to address the United Nations General Assembly.

Mr Biden earlier on Thursday attended a fundraiser for the Democratic National Committee in New Jersey at the Middletown home of Governor Phil Murphy, a former Goldman Sachs Group executive. AFP, BLOOMBERG