On Sept. 26, 1983 the Soviet Union’s Oko early warning system reported that the US had launched five intercontinental ballistic missiles. Lt. Col. Stanislav Petrov, the duty officer at the Serpukhov-15 bunker, broke protocol and refused to report the alert as a confirmed strike. He reasoned that a real US first strike would involve hundreds or thousands of missiles, not five. The system, it turned out, had mistaken sunlight reflecting off clouds for missile launches. Petrov’s decision to defy pr
