Russian President Vladimir Putin is fond of nuclear saber-rattling: On the eve of Russia’s full-scale invasion of Ukraine in February 2022, the Kremlin leader presided over the rehearsal of a nuclear strike,

Putin has extended the list of scenarios that could lead to Russia using nuclear weapons. Whether he means it is a question critical to the course of the war. If he is serious, the conflict could turn into World War Three.

Dmitry Medvedev, a long-time ally of Russian President Vladimir Putin, has laid out the country's new deterrence policy against Western "aggression," and warned that provocations by Ukraine and its allies could result in nuclear war.