56 years ago this week, the United States and Soviet Union were on the verge of all-out nuclear war. Suddenly, American families learned that they were in the crosshairs of Soviet nuclear-tipped missiles stationed 90 miles away from Florida, and virtually the entire continental U.S. was now moments away from annihilation. We know how the Cuban Missile Crisis ended, but how did it come about in the first place? During the early days of the Cold War, the Soviet Union had a big problem: mutually assured destruction only works when both sides can assure destruction. The United States could target...