The Cuban Missile Crisis is regarded as the closest the world has ever come to nuclear war.

The largest "nuke" was the Soviet Tsar Bomba.

The most recent nuclear test was by Korea, on Oct. 9, 2006.

The Limited Test Ban Treaty banned all kinds of nuclear tests, i.e. underwater, save for underground ones. 

by Marcelo

 
Mushroom Cloud
National Archives

The Cuban Missile Crisis is regarded as the closest the world has ever come to nuclear war. The beginning and end of the Crisis, as well as nuclear weapons threatened to be used, are all accounted for below.

The Crisis was mainly started by two countries in 1962, one of them the USSR. A Soviet leader, Nikita Khrushchev, was worried about the fact that the US had nuclear missiles only 150 miles away in Turkey, short work for a missile. Also, Khrushchev knew that no matter what Kennedy, President at the time, said while in his campaign, the Americans had more missiles than the Soviets. Thus, the USSR felt endangered. The other main cause was the Cuban fear of a US invasion. Ever since the failed Bay of Pigs assault, Fidel Castro, a Cuban dictator, had feared another, perhaps more successful, invasion of Cuba. As a result, Castro turned to the Soviets for protection. Khrushchev knew that the US was drafting "Operation Mongoose", a mock plan to invade Cuba and was only too glad to place nuclear missiles only 90 miles from the American coast. With the installment of the missiles, the Crisis was on.

Nuclear missiles were the central factor in the Cuban Missile Crisis. But exactly what is a nuclear weapon anyway? Nuclear weapons or "nukes" as they are sometimes referred to, derive their terrible abilities from nuclear reactions of fission or fusion, allowing them to level entire cities. This weapon of mass destruction has only been used twice in history, both in World War II, both on Japan, and both manufactured by the USA. The two weapons were codenamed "Fat Man" and "Little Boy." At the Trinity Site the first atomic weapon was detonated with a probable yield of 20 kilotons. The first hydrogen bomb, "Mike," and was tested on Nov. 1, 1952 in the Enewetak atoll in the Marshall Islands by the US. The largest nuclear weapon, the Soviet "Tsar Bomba" had an approximate yield of 50 megatons and was tested at Novaya Zemlya on Oct. 30, 1961. In 1963, every nuclear and many non-nuclear countries signed the Limited Test Ban Treaty, which made them pledge to cease nuclear testing in the atmosphere, underwater, or in outer space. However, the treaty permitted underground tests. The last US test was in 1992, and the most recent test was done by North Korea on Oct. 9, 2006.