Stanislav Yevgrafovich Petrov (Russian: Станисла́в Евгра́фович Петро́в; 7 September 1939 – 19 May 2017) was a lieutenant colonel of the Soviet Air Defence Forces who played a key role in the 1983 Soviet nuclear false alarm incident. On 26 September 1983, three weeks after the Soviet military had shot down Korean Air Lines Flight 007, 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 to disobey orders, against Soviet military protocol, is credited with having prevented an erroneous retaliatory nuclear attack on the United States and its NATO allies that could have resulted in the Third World War and a large-scale nuclear war which could have wiped out half of the population of the countries involved. An investigation later confirmed that the Soviet satellite warning system had indeed malfunctioned. Because of this incident, Petrov is often credited as having "saved the world".