From the 1940s to the 1990s the United States and the former Soviet Union (USSR) confronted each other in a cold war. Each side feared and distrusted the other. Each side was prepared to respond to an attack with immediate nuclear retaliation. Although this stance of “mutually assured destruction” helped to avoid all-out war, the cold war threatened to turn hot on several occasions. Perhaps the most notable of these events occurred in the autumn of 1983, when the USSR mistakenly interpreted “Able Archer,” a routine military exercise from the North Atlantic Treaty Organisation, as cover for an impending first strike. The US compounded the error by failing to recognise Soviet fears and continuing military activities as planned, pushing Soviet leaders close to their own pre-emptive first strike attack and catastrophic nuclear war.