President Joe Biden has warned that the threat of Russian President Vladimir Putin using tactical nuclear weapons is “real,” as Ukraine's counteroffensive rolls on.

North Korean leader Kim Jong Un has overseen drills simulating a nuclear counterattack against the U.S. and South Korea in a warning to the allies.

China's stockpile of nuclear warheads has surpassed 400 in a fraction of the time previously estimated by the United States, a major Pentagon report revealed, with Beijing focusing on accelerating its nuclear expansion as it seeks to challenge the US as the world's top super power.