US President Biden says the world is facing nuclear "Armageddon", warning that Vladimir Putin may use his atomic arsenal as Russian troops struggle against a Ukrainian counter-offensive.

Biden also challenges the Russian nuclear doctrine, warning that the use of a lower-yield tactical weapon could quickly spiral out of control.
Biden also challenges the Russian nuclear doctrine, warning that the use of a lower-yield tactical weapon could quickly spiral out of control. (AP)

President Joe Biden has said the risk of nuclear “Armageddon” is at the highest level since the 1962 Cuban Missiles Crisis, remarks that come amid concerns about the possibility of Moscow using tactical nuclear weapons after suffering setbacks in Ukraine.

Speaking at a fundraiser for the Democratic Senatorial Campaign Committee on Thursday, Biden said Russian President Vladimir Putin was “a guy I know fairly well” and the Russian leader was “not joking when he talks about the use of tactical nuclear weapons or biological or chemical weapons”.

Biden made clear he was keeping a wary eye on Putin and how he might react as Ukraine's military makes gains against the Russian army, marking the starkest warnings yet issued by the US government about the nuclear stakes.

"For the first time since the Cuban Missile Crisis, we have a direct threat to the use of nuclear weapons, if in fact things continue down the path they'd been going," Biden told in New York.

He also said, "We have not faced the prospect of Armageddon since Kennedy and the Cuban missile crisis."

In the 1962 Cuban Missile Crisis, the United States under President John Kennedy and Soviet Union under its leader, Nikita Khrushchev, came close to the use of nuclear weapons over the presence of Soviet missiles in Cuba.

Biden suggested the threat from Putin is real “because his military is — you might say — significantly underperforming.”

READ MORE: Zelenskyy sounds alarm as US warns Russia against nukes in Ukraine

Tensions simmer

It was not immediately clear whether Biden was referring to any new assessment of Russian intentions. As recently as this week, though, US officials have said they have seen no change to Russia’s nuclear forces that would require a change in the alert posture of US nuclear forces.

And earlier this week, the Kremlin said it favoured a “balanced approach” to the issue, after a Chechen ally of Putin called for the use of “low-yield nuclear weapon” in the face of Ukraine's counter-offensive that has forced the Russian army to retreat from swathes of territory in the east and the south.

As temperatures soar, observers however point out that Putin has repeatedly alluded to using his country's vast nuclear arsenal, including last month when he announced plans to conscript Russian men to serve in Ukraine.

In his speech, Biden also challenged the Russian nuclear doctrine, warning that the use of a lower-yield tactical weapon could quickly spiral out of control into global destruction.

“I don’t think there is any such a thing as the ability to easily use a tactical nuclear weapon and not end up with Armageddon,” Biden said.

He added that he was still “trying to figure” out Putin's “off-ramp” in Ukraine.

“Where does he find a way out?” Biden asked. "Where does he find himself in a position that he does not not only lose face but lose significant power within Russia?”

Ukraine President Volodymyr Zelenskyy said earlier on Thursday that Putin understood that the “world will never forgive” a Russian nuclear strike.

“He understands that after the use of nuclear weapons he would be unable any more to preserve, so to speak, his life, and I’m confident of that,” Zelenskyy said.

But a September speech by Putin has sparked concerns in some quarters, with a section of observers calling it a thinly veiled threat.

“I want to remind you that our country also has various means of destruction... and when the territorial integrity of our country is threatened, to protect Russia and our people, we will certainly use all the means at our disposal,” Putin said on September 21, adding with a lingering stare at the camera, “It’s not a bluff.”

The 13-day showdown in 1962 that followed the US discovery of the Soviet Union's secret deployment of nuclear weapons to Cuba is regarded by experts as the closest the world has ever come to nuclear annihilation. The crisis sparked a renewed focus on arms control on both sides of the Iron Curtain.

READ MORE: No one can win a nuclear war, should never be unleashed: Putin

Source: TRTWorld and agencies