The world will mark the 60th anniversary of the Cuban Missile Crisis, which is known to Russians as the Caribbean Crisis, in October. The incredibly tense confrontation brought the United States and the Soviet Union the closest they would come to nuclear war during the Cold War.

The crisis has fresh relevance today in the weeks after Russia’s unprovoked invasion of Ukraine. Russian President Vladimir Putin has indicated that using his country’s nuclear weapons stockpile is a possibility, and Western experts have not disputed that such use could happen.

While Putin employing nuclear weapons remains unlikely, experts say some situations may cause the Russian leader to lash out. These include Russia losing the war badly, the country being crushed by economic sanctions, or Putin feeling as though his hold on power is threatened. Were some or all of these things to happen, Putin could conceivably turn to his option of last resort. A nuclear strike could take the form of a demonstration over an unpopulated area, or perhaps even a tactical blow in Ukraine. Such a move would almost certainly force a response from the West.