Russian President Vladimir Putin has ordered his military's nuclear deterrent forces to be on alert as international tension builds over Russia's four-day-old invasion of Ukraine.
Putin said in a meeting of top officials on Sunday that the move was in response to leading NATO powers making what he called “aggressive statements,” according to Tass, the state-owned Russian news agency.
Russia, like the United States, has thousands of nuclear warheads that it maintains as a deterrent to an attack.
