On September 26, 1983, the world came very close to nuclear war. Shortly after midnight, alarms inside Serpukhov-15—a bunker in Moscow where the Soviet Union monitored its satellites over the United States—began to go off. The satellites had detected the launch of an intercontinental ballistic missile from a base in the United States. Then the system reported that five missiles had been launched and were heading toward the Soviet Union from the U.S.
Lieutenant Colonel Stanislav Petrov, who was on duty that night, had no way of knowing that it was a false alarm: The satellites had mistaken the reflections of sunlight off high-altitude clouds as a missile launch. He had only a few minutes to determine if this was a genuine attack. In that case, Soviet protocol was an immediate counterattack.
It was a tense time in U.S.-Soviet relations. On September 1, the Soviets had shot down a South Korean passenger plane that strayed into its airspace, killing a number of Americans. The United States was performing naval maneuvers near key Soviet military sites. And preparations were underway for Able Archer 83, a 10-day NATO exercise in Western Europe that included a simulated DEFCON 1 nuclear alert. Some Soviets thought Archer was a ruse for war that would mask the preparations for a genuine nuclear strike.
On Second Thought...
Under immense pressure, Petrov ultimately decided that the satellites were wrong. In addition to what he called “a funny feeling in my gut," he had other evidence to suggest reports of an attack were false. Ground-based radar hadn’t detected any incoming missiles, even a few minutes after the satellite alarm (the delay is because ground-based radar can’t see over the horizon). What’s more, Petrov had been told any attack would be a full barrage of missiles, not just five, and he knew that the system had flaws. He reported his findings to his superiors, who did not launch an attack.
Though he was at first praised for his decision, Petrov was later interrogated intensely, and in the end, was not punished or rewarded for being a key part of averting nuclear war and saving the world.