In 1983, during a tense period of the Cold War, Soviet nuclear officials received a computer warning suggesting that the United States had fired five nuclear missiles towards Moscow. Fortunately, the officer on duty, Lieutenant Colonel Stanislav Petrov, realised the warning was a false alarm and advised his commanders against a retaliatory strike against America. Alex Last hears his story, as told in 2008 to the BBC's Jonathan Charles. Stanislav Petrov died in 2017.

PHOTO: Stanislav Petrov pictured in 2004 (Getty Images)