https://en.wikipedia.org/wiki/1983_Soviet_nuclear_false_alarm_incident
On 26 September 1983, Stanislav Petrov, a lieutenant colonel in the Soviet Air Defense Forces, was the officer on duty at the Serpukhov-15 bunker near Moscow which housed the command center of the Soviet early warning satellites, code-named Oko.[5] Petrov's responsibilities included observing the satellite early warning network and notifying his superiors of any impending nuclear missile attack against the Soviet Union. If notification was received from the early warning systems that inbound missiles had been detected, the Soviet Union's strategy was an immediate nuclear counter-attack against the United States (launch on warning), specified in the doctrine of mutual assured destruction.[6]
Shortly after midnight, the bunker's computers reported that one intercontinental ballistic missile was heading toward the Soviet Union from the United States. Petrov considered the detection a computer error, since a first-strike nuclear attack by the United States was likely to involve hundreds of simultaneous missile launches in order to disable any Soviet means of a counterattack. Furthermore, the satellite system's reliability had been questioned in the past.[7] Petrov dismissed the warning as a false alarm, though accounts of the event differ as to whether he notified his superiors[6] or not[3][full citation needed] after he concluded that the computer detections were false and that no missile had been launched. Later, the computers identified four additional missiles in the air, all directed towards the Soviet Union. Petrov again suspected that the computer system was malfunctioning, despite having no other source of information to confirm his suspicions. The Soviet Union's land radar was incapable of detecting missiles beyond the horizon,[7] and waiting for it to positively identify the threat would limit the Soviet Union's response time to a few minutes.[citation needed]
It was subsequently determined that the false alarms were caused by a rare alignment of sunlight on high-altitude clouds and the satellites' Molniya orbits, an error later corrected by cross-referencing a geostationary satellite.[8]
In explaining the factors leading to his decision, Petrov cited his belief and training that any U.S. first strike would be massive, so five missiles seemed an illogical start.[6] In addition, the launch detection system was new and in his view not yet wholly trustworthy, while ground radar had failed to pick up corroborative evidence even after several minutes of the false alarm.[7]
Petrov underwent intense questioning by his superiors about his actions. Initially, he was praised for his decision.[6] General Yury Votintsev, then commander of the Soviet Air Defense's Missile Defense Units, who was the first to hear Petrov's report of the incident (and the first to reveal it to the public in the 1990s), states that Petrov's "correct actions" were "duly noted."[6] Petrov himself states he was initially praised by Votintsev and was promised a reward,[6][9] but recalls that he was also reprimanded for improper filing of paperwork with the pretext he had not described the incident in the military diary.[9][10]