US President Joe Biden said Thursday the world is risking nuclear “Armageddon” for the first time since the Cold War and he is trying to find Russian President Vladimir Putin’s “exit” in the Ukraine conflict.

“We haven’t faced the prospect of Armageddon since Kennedy and the Cuban Missile Crisis in 1962,” Biden said at a Democratic Party fundraiser in New York, referring to former US President John F. Kennedy.

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

The president made his unusually harsh comments on the risks posed by Putin’s nuclear threats while speaking to party supporters at an event at the Manhattan home of James Murdoch, son of newspaper mogul Rupert Murdoch.

Referring to the nuclear standoff 60 years ago, triggered by the Soviet Union’s deployment of missiles in Cuba within range of the United States, Biden said that “for the first time since the Cuban Missile Crisis, we have a direct threat of using nuclear weapons Arms if things really do continue as they are.”

“We’re trying to figure out what Putin’s exit is,” Biden said.

Putin has issued thinly-veiled threats to use nuclear weapons when he feels he has run out of options in his attempt to seize parts of Ukrainian territory in the face of stiff opposition from western defender Kyiv.

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

“We have a guy that I know pretty well,” Biden said. Putin “doesn’t joke when he talks about the possible use of tactical nuclear weapons or biological or chemical weapons because his military is, you could say, well below average.”

But “I don’t think there’s such a thing as the ability to just[deploy]a tactical nuclear weapon and not end up with Armageddon,” Biden said.

The president’s comments come as Ukraine has reclaimed new territory from Russian forces, the latest in a string of Moscow defeats that undermine the Kremlin’s claim to have annexed around 20 percent of Ukraine.

But with Russia’s once-vaunted military stalled, Washington and its Western allies are worried about what Putin might be planning on the battlefield.

“Where does he find a way out?” asked Biden.

“Where is he in a position where he loses not only face but significant power within Russia?”