Nuclear 'Armageddon' risk highest since '62 crisis': Biden

President Joe Biden said Thursday that the risk of nuclear Armageddon is at the highest level since the 1962 Cuban Missile Crisis, as Russian officials speak of the possibility of using tactical nuclear weapons after suffering massive setbacks in the eight-month invasion of Ukraine.

Speaking at a fundraiser for the Democratic Senatorial Campaign Committee, Biden said Russian President Vladimir Putin was not joking when he talks about the use of tactical nuclear weapons or biological or chemical weapons.

Biden added, We have not faced the prospect of Armageddon since Kennedy and the Cuban Missile Crisis."

Biden also challenged 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 there is any such a thing as the ability to easily use a tactical weapon and not end up with Armageddon, Biden said.

US officials for months have warned of the prospect that Russia could use weapons of mass destruction in Ukraine as it has faced a series of strategic setbacks on the battlefield as recently as this week. Though, they 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.

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.