The document discusses America's blockade of Cuba during the Cuban Missile Crisis when the Soviet Union attempted to place nuclear missiles on the island. It explores America's fear that communism was spreading globally during the Cold War and could envelop more countries like Cuba. The blockade was an attempt to prevent Cuba from becoming too aligned with the oppressive Soviet Union and its leader Stalin, who killed millions of people, and to stop the "domino effect" of communism toppling more nations as described by Eisenhower's Domino Theory.