1983 Soviet nuclear false alarm incident

On September 26, 1983, the nuclear early warning system of the Soviet Union twice reported the launch of American Minuteman ICBMs from bases in the United States. These missile attack warnings were correctly identified as a false alarm by Stanislav Yevgrafovich Petrov, an officer of the Soviet Air Defence Forces. This decision is seen as having prevented an erroneous retaliatory nuclear attack on the United States and its NATO allies, which would have likely resulted in nuclear war and the potential deaths of millions of people. Investigation of the satellite warning system later confirmed that the system had malfunctioned.

Background
The incident occurred at a time of severely strained relations between the United States and the Soviet Union. Only three weeks earlier, the Soviet military had shot down a South Korean passenger jet, Korean Air Lines Flight 007, that had strayed into Soviet airspace, killing all 269 people on board. Many Americans were killed, including U.S. Congressman Larry McDonald.

Bruce Blair, an expert on Cold War nuclear strategies and former president of the World Security Institute in Washington, D.C., says the American–Soviet relationship at that time "had deteriorated to the point where the Soviet Union as a system — not just the Kremlin, not just Soviet leader Yuri Andropov, not just the KGB — but as a system, was geared to expect an attack and to retaliate very quickly to it. It was on hair-trigger alert. It was very nervous and prone to mistakes and accidents. The false alarm that happened on Petrov's watch could not have come at a more dangerous, intense phase in U.S.–Soviet relations." In an interview aired on American television, Blair said, "The Russians [Soviets] saw a U.S. government preparing for a first strike, headed by a President [ Ronald Reagan ] capable of ordering a first strike." Regarding the incident involving Petrov, he said, "I think that this is the closest we've come to accidental nuclear war."

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. 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.

Shortly after midnight, the bunker's computers reported that one intercontinental ballistic missile was heading toward the Soviet Union from the U.S. 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. Petrov dismissed the warning as a false alarm, though accounts of the event differ as to whether he notified his superiors or not 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, and waiting for it to positively identify the threat would limit the Soviet Union's response time to a few minutes.

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.

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. 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.

Aftermath
Petrov underwent intense questioning by his superiors about his actions. Initially, he was praised for his decision. Gen. 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." Petrov himself states he was initially praised by Votintsev and was promised a reward, 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.

The incident became known publicly in the 1990s following the publication of Gen. Votintsev's memoirs. Widespread media reports since then have increased public awareness of Petrov's actions.

Some Cold War analysts question whether the Soviet Union's standard protocol requiring multiple-source warnings would have been strictly followed in the case of the missile attack warning involving Petrov.

Oleg Kalugin, a former KGB chief of foreign counter-intelligence who knew Soviet chairman Andropov well, says that Andropov's distrust of American leaders was profound. It is conceivable that if Petrov had declared the satellite warnings valid, such an erroneous report could have provoked the Soviet leadership into becoming bellicose. Kalugin says, "The danger was in the Soviet leadership thinking, 'The Americans may attack, so we better attack first.'"