September 26 2020 — On September 26 1983 — just three weeks after the Soviet military had shot down Korean Air Lines Flight 007 — Stanislav Petrov was the duty officer at the command center for the Oko nuclear early-warning system when the system reported that a missile had been launched from the United States, followed by up to five more.
Petrov judged the reports to be a false alarm and his decision is credited with having prevented an erroneous retaliatory nuclear attack on the United States and its NATO allies that could have resulted in large-scale nuclear war. Investigation later confirmed that the Soviet satellite warning system had indeed malfunctioned. Follow us on Twitter: @INTEL_TODAY
UPDATE (September 26 2021) — On August 1 1984, President Ronald Reagan joked about nuking Russia during a sound check for his Saturday radio address.
Reporters and technicians in the room laughed at the joke. Then the tape was leaked. And the Russians were not amused… The Pentagon confirmed that Soviets were actually, and understandably, on war alert.
Embarrassed U.S. officials quickly assured the Kremlin that Reagan’s offhand remark did not reflect White House policies or U.S. military intentions.
What if? Ask yourself a simple question. What if Reagan had told his great joke a year earlier and the tape had been leaked a few days before September 26 1983?
“Petrov had to make a decision: Would he report an incoming American strike? If he did, Soviet nuclear doctrine called for a full nuclear retaliation. There would be no time to double-check the warning system, much less seek negotiations with the US.” [A nuclear conflict with Russia is likelier than you think — Max Fisher]
Obviously, Colonel Stanislav Petrov may have reached a very different conclusion…
END of UPDATE
On September 26 1983, false alarm at a Soviet command center nearly led to nuclear war.
Stanislav Petrov , a lieutenant colonel in the Soviet Air Defence Forces, was in charge at a secret bunker near Moscow when an alarm sounded, indicating that the US had launched a nuclear missile.
“The incident took place at a particularly tense time during the Cold War, as the USSR had shot down a South Korean passenger jet in Soviet airspace just three weeks before.
If the US launched a nuclear attack, the Russians almost certainly would have retaliated with a devastating counterattack.
Fortunately, Petrov showed poise and restraint.
He had a hunch the warning was a false alarm, and he held to that view even when the computer system reported the launch of four more Minuteman intercontinental ballistic missiles.
Petrov later said the main reason for his conclusion was that the US would have launched a nuclear attack with a barrage of missiles, not five, to cripple the USSR.
He also doubted the satellite-based early-warning technology; the more reliable ground-based radar, which would have picked up the incoming missiles minutes later, showed nothing out of the ordinary.” [Physics Today]
On this day in 1983, Colonel Petrov simply saved the world.
He was not even supposed to be on duty. He was replacing a sick colleague. Many of his colleagues — probably all of them — would have most likely followed the procedure.
Petrov died on May 19 2017 at the age of 77.
“The Man Who Saved The World”
Nuclear false alarm — Physics Today
THIS DAY IN HISTORY — Stanislav Petrov Saved the World from Nuclear War
On This Day — Stanislav Petrov Saves the World from Nuclear War (Sept. 26 1983)
On This Day — Stanislav Petrov Saves the World from Nuclear War (September 26 1983) 
On This Day — Stanislav Petrov Saves the World from Nuclear War (September 26 1983)