WARNING. This article may be nuked (not to joke about the real thing).
Several weeks after the downing of Korean Air Lines Flight 007 over Soviet airspace, a satellite early-warning system near Moscow reported the launch of one American Minuteman ICBM. Soon after, it reported that five missiles had been launched. Convinced that a real American offensive would involve many more missiles, Lieutenant Colonel Stanislav Petrov of the Air Defense Forces refused to acknowledge the threat as legitimate and continued to convince his superiors that it was a false alarm until this could be confirmed by ground radar.[5][40][41][42][43][44][45][excessive citations]
Able Archer 83 was a command post exercise carried out by NATO military forces and political leaders between 7 and 11 November 1983.[46] The exercise simulated a Soviet conventional attack on European NATO forces 3 days before the start of the exercise (D-3), transitioning to a large scale chemical war (D-1) and on day 1 (D+1) of the exercise, NATO forces sought political guidance on the use of nuclear weapons to stem the Soviet advance which was approved by political leaders. NATO then began simulating preparations for a transition to nuclear war.[47]
These simulations included 170 radio-silent flights to air lift 19,000 US troops to Europe, regularly shifting military commands to avoid nuclear attack, the use of new nuclear weapon release procedures, the use of nuclear Command, Control, and Communications (C3) networks for passing nuclear orders, the moving of NATO forces in Europe through each of the alert phases from DEFCON 5 to DEFCON 1, and the participation of political leaders like Margaret Thatcher, Helmut Kohl and Ronald Reagan.[48]
The issue was worsened by leaders referring to B-52 sorties as "nuclear strikes",[48] by the increased use of encrypted diplomatic channels between the US and UK,[49] and by the nuclear attack false alarm in September.
In response, Soviet nuclear capable aircraft were fueled and armed ready to launch on the runway, and ICBMs were brought up to alert. Soviet leaders believed the exercise was a ruse to cover NATO preparations for a nuclear first strike and frantically sent a telegram to its residencies seeking information on NATO preparations for an attack. The exercise closely aligned with Soviet timeline estimations that a NATO first strike would take 7 to 10 days to execute from the political decision being made.[50][51]
Soviet forces stood down after 11 November when the exercise ended. NATO was unaware of the complete Soviet response until British intelligence asset Oleg Gordievsky passed on the information.[52]