Biden Says Putin's Nuclear Threat Brings Risk Of 'Armageddon'

Russian President Vladimir Putin's threat to use nuclear weapons in Ukraine has brought the world closer to "Armageddon" than at any time since the Cold-War Cuban Missile Crisis, U.S. President Joe Biden said.

As Putin's seven-month invasion unravels, Ukrainian President Volodymyr Zelenskiy said Kyiv's forces were swiftly recapturing more territory, including more than 500 sq km in the south where they burst through a second major front this week.

Russia's failings on the battlefield have brought unusual public recrimination from Kremlin allies, with one Russian-installed leader in occupied Ukrainian territory going so far as to suggest Putin's defence minister should have shot himself.

Biden said the prospect of defeat could make Putin, who was 70 on Friday, desperate enough to use nuclear weapons, the biggest risk since U.S. President John Kennedy and Soviet leader Nikita Khrushchev faced off over missiles in Cuba in 1962.

"We have not faced the prospect of Armageddon since Kennedy and the Cuban missile crisis," Biden said in New York. "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."

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

Concern so far has been over the prospect of Russia deploying a so-called "tactical" nuclear weapon - a short-range device for use on the battlefield - rather than the "strategic" weapons on long-range missiles that Washington and Moscow have stockpiled since the Cold War.

But Biden suggested it made little difference: "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."

Putin has warned he would use all means necessary, including Russia's nuclear arsenal, to protect Russian soil, which he now says includes four Ukrainian regions he declared annexed last week.

In remarks to Australia's Lowy Institute, Zelenskiy said NATO should launch preventive strikes on Russia to preclude its use of nuclear weapons.

Kremlin spokesman Dmitry Peskov denounced those comments as "an appeal to start yet another world war with unpredictable, monstrous consequences". Russian Foreign Minister Sergei Lavrov said Zelenskiy's remarks demonstrated why Russia was right to launch its operation.