NEW YORK/KYIV, Oct 7 (Reuters) – 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...