Wired: During 10 days in November 1983, the United States and the Soviet Union nearly started a nuclear war. Newly declassified documents from the CIA, NSA, KGB, and senior officials in both countries reveal just how close we came to mutually assured destruction — over a military exercise.

That exercise, Able Archer 83, simulated the transition by NATO from a conventional war to a nuclear war, culminating in the simulated release of warheads against the Soviet Union. NATO changed its readiness condition during Able Archer to DEFCON 1, the highest level. The Soviets interpreted the simulation as a ruse to conceal a first strike and readied their nukes. At this period in history, and especially during the exercise, a single false alarm or miscalculation could have brought Armageddon.

According to a diplomatic memo obtained through a Freedom of Information Act request by National Security Archives researcher Nate Jones, Soviet General Secretary Yuri Adroprov warned U.S. ambassador Averell Harriman six months before the crisis that both countries “may be moving toward a red line” in which a miscalculation could spark a nuclear war. Harriman later wrote that he believed Andropov was concerned “over the state of U.S.-Soviet relations and his desire to see them at least ‘normalized,’ if not improved.”

The early 1980s was a “crisis period, a pre-wartime period,” said Gen. Varfolomei Korobushin, the former deputy chief of staff of the Soviet nuclear Strategic Rocket Forces, according to an interview conducted by the Pentagon in the early 1990s and obtained by Jones. The Kremlin’s Central Committee slept in shifts. There were fears the deployment of Pershing II ballistic missiles to Europe (also in November 1983) could tip the balance. If a conventional war erupted, Soviet planners worried their troops would come close to capturing the nuclear-tipped missiles, prompting the United States to fire them. [Continue reading…]