How did the Cuban missile crisis bring the United States and Soviet Union close to war?

The Cuban missile crisis brought the United States and the Soviet Union to the brink of nuclear war in October 1962 after the Soviets began secretly installing nuclear-armed ballistic missiles in Cuba. These weapons were capable of striking much of the eastern United States within minutes.12

The confrontation escalated when U.S. U-2 spy planes confirmed the presence of these launch sites. In response, President John F. Kennedy implemented a naval blockade—termed a "quarantine"—to prevent further Soviet shipments. As the superpowers hovered near conflict, the world faced its closest encounter with global nuclear war.13

The crisis concluded when Soviet Premier Nikita Khrushchev agreed to remove the missiles in exchange for a U.S. pledge not to invade Cuba and a secret agreement to withdraw American missiles from Turkey. This event underscored the terrifying reality of mutual atomic annihilation and led to subsequent efforts to manage nuclear tensions, such as the Nuclear Test-Ban Treaty.12