The tension in Europe between the United States and Soviet Union following World War II was escalated with Cuba's involvement because...

a. Castro's relationship with Khrushchev appeared to be a threat to America's safety.
b. Kennedy attempted to create alliances with Cuba in order to overthrow the Soviet Union.
c. Kennedy ordered an invasion of the Soviet Union off the northern coast of Russia.
d. Castro supported Khrushchev's efforts to secretly invade the United States off the Gulf Coast.

a. Castro's relationship with Khrushchev appeared to be a threat to America's safety.

The correct answer is a. Castro's relationship with Khrushchev appeared to be a threat to America's safety.

Following the Cuban Revolution in 1959, Fidel Castro established a close relationship with Soviet Premier Nikita Khrushchev. This relationship was seen by the United States as a threat to its safety because it led to the installation of Soviet nuclear missiles in Cuba in 1962. The potential for nuclear weapons so close to the United States caused a heightened level of tension between the United States and the Soviet Union, and the situation became known as the Cuban Missile Crisis. The United States responded by imposing a naval blockade on Cuba, leading to a standoff between the two superpowers and bringing the world to the brink of nuclear war.