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, News.az reports citing local media.

With his seven-month invasion unravelling, Putin celebrated his 70th birthday on Friday with fawning praise from some officials but little public fuss. That was a contrast to just a week ago when he staged a huge concert on Red Square to proclaim the annexation of nearly a fifth of Ukrainian land.

In a clear repudiation of Putin's record, the Nobel Peace Prize was awarded to Russia's most prominent human rights group, Memorial, which Moscow shut down over the past year. A Ukrainian human rights group and a jailed campaigner against abuses by the pro-Russian government in Belarus also shared the award.

Ukrainian President Volodymyr Zelenskiy said Kyiv's forces were swiftly recapturing more territory, including more than 500 square kilometres (200 square miles) in the south where they burst through a second major front this week.