President Joe Biden stated on Thursday that the potential of a nuclear "Armageddon" is at its greatest level since the Cuban Missile Crisis of 1962, as Russian authorities discuss the idea of using tactical nuclear weapons following huge losses in their eight-month invasion of Ukraine.

Biden, speaking at a fundraiser for the Democratic Senatorial Campaign Committee, described Russian President Vladimir Putin as "a guy I know fairly well" and stated that Putin "is not joking" when he discusses the use of tactical nuclear weapons or biological and chemical weapons.

Biden added, "We have not faced the possibility of Armageddon since the Cuban Missile Crisis and the Kennedy administration." He claimed that the threat posed by Vladimir Putin is real "because his military is significantly underperforming."

As Russia has suffered a series of strategic setbacks on the battlefield, US officials have for months warned of the possibility that Russia could use weapons of mass destruction in Ukraine. However, Biden's remarks represented the direst warnings yet from the US government about the nuclear stakes.

It was unclear whether Biden was referring to a new assessment of Russian intentions when he made his statement.

US officials have stated as recently as this week that they have not observed any changes to Russia's nuclear forces that would need a change in the alert posture of US nuclear forces.

Tuesday, White House press secretary Karine Jean-Pierre stated, "We have seen no reason to adjust our own strategic nuclear posture, nor do we have any indication that Russia is preparing to use nuclear weapons imminently."

According to experts, the 13-day confrontation in 1962 that followed the United States revelation of the Soviet Union's secret deployment of nuclear weapons to Cuba was the closest the world ever came to nuclear catastrophe.

The crisis that occurred under the presidency of John F. Kennedy refocused attention on arms control on both sides of the Iron Curtain.

Biden also criticized the Russian nuclear doctrine, stating that the use of a tactical bomb with a lesser yield may rapidly escalate out of hand and cause a global disaster.

Biden stated, "I do not believe it is possible to use a tactical nuclear weapon without bringing about Armageddon."

He said that he was still "attempting to determine" Putin's "exit strategy" in Ukraine.

"From where does he escape?" Biden asked. Where did he come to be in a position where he not only loses face but also tremendous power within Russia?

Putin has regularly alluded to the use of his country's enormous nuclear weapons, most recently when he revealed plans to recruit Russian men to serve in Ukraine last month.

"I would want to remind you that our nation possesses a variety of destructive capabilities... "When the territorial integrity of our country is threatened, we will certainly use all the means at our disposal to protect Russia and our people," Putin stated on September 21, adding with a lingering gaze at the camera, "This is not a bluff."

The national security adviser of the White House, Jake Sullivan, stated last week that the US had "made clear" to Russia the "consequences" of using nuclear weapons in Ukraine.

"This is something we are aware of, taking very seriously, and communicating directly with Russia about, including the kind of decisive responses we would take if they proceeded down this path," Sullivan said.

President of Ukraine Volodymyr Zelenskyy stated earlier on Thursday that Putin is aware that "the world will never forgive" a nuclear strike by Russia.

"I am confident that he understands that after the use of nuclear weapons, he would no longer be able to preserve his life," Zelenskyy added.

Biden made his remarks at a private event for Democratic Senate candidates hosted by James and Kathryn Murdoch in Manhattan. In such circumstances, which are restricted to a small number of reporters without cameras or recording equipment, he tends to be less cautious and frequently speaks without notes.