Describe how the usa and ussr almost went to war over cuba in 1962.

Because The Cuban Missile Crisis. In 1962, The Soviet Union, in collaboration with Fidel Castro, began building nuclear missiles on the Island of Cuba. Because the Soviets technology at the time limited their nuclear missiles range, they felt that having missiles in Cuba was the only way of defending against an attack by the United States, whose nuclear arsenal could reach the Soviet Union at any time.
Castro, after the failed Bay of Pigs invasion, thought that another attack by the U.S was inevitable and agreed to the Soviet installations.
President Kennedy imposed a quarantine on the island by surrounding it with naval vessels and ordered the missiles to be dismantled. Several tense days went by, and the world was on the brink of nuclear war. the worst day being October 27th when a U2 reconnaissance plane was shot down.
On October 28th, The U.S and the Soviet Union came to an agreement. The missiles and bombers would be removed from Cuba, and the U.S agreed not to invade Cuba, thus ending the crisis.