Jeb Bush is the former governor of Florida. Frank Calzon is executive director of the Center for a Free Cuba in Washington, D.C.

Fifty years ago, the world was on the brink of Armageddon.

The Russians had secretly installed nuclear missiles in Cuba, aiming them at Washington and other American cities. Confronting the Soviet Union at the United Nations, the United States displayed photographic evidence and demanded the missiles be removed. On Oct. 22, 1962, President John F. Kennedy ordered the Navy to blockade Cuba. Six days later Soviet Premier Nikita S. Khrushchev ordered the missiles dismantled.

How did that crisis develop? What lessons were learned that might be applied in these still-perilous times? The first lesson actually stems from Kennedy’s first meeting with Khrushchev in Vienna. Recently elected, Kennedy, 45, was young, dashing and charismatic. Khrushchev, 68, was a committed Communist who had been trained by Stalin, one of history’s most brutal tyrants. Sometime during the meeting Khrushchev concluded Kennedy was a light-weight and could be pushed around...