“The Soviets had ... built an early warning radar system with computer linkages using a primitive kind of AI code-named Oko. On September 26, 1983, ... the system malfunctioned and reported 5 incoming ICBMs from the United States. Oko alarms sounded and the computer screen flashed "LAUNCH." Under the protocols, the "LAUNCH" display was not a warning but a computer-generated order to retaliate.
Lieutenant Colonel Stanislov Petrov of the Soviet Air Defense Forces saw the computer order and had to choose immediately between treating the order as a computer malfunction or alerting to senior officers, who would likely commence a counterattack. Petrov was Oko's codeveloper and knew the system made mistakes. He also estimated that if the attack were real, the U.S. would use far more than 5 missiles. Petrov was right. The computer had misread the sun's reflection off nearby clouds as incoming missiles.”