<P> Just six months after the UN General Assembly, the United States conducted its first post-war nuclear tests . This was called Operation Crossroads . The purpose of this operation was to test the effectiveness of nuclear explosions on ships . These tests were performed at Bikini Atoll in the Pacific on 95 ships, including German and Japanese ships that were captured during World War II . One plutonium implosion - type bomb was detonated over the fleet, while the other one was detonated underwater . </P> <P> Behind the scenes, the Soviet government was working on building its own atomic weapons . During the war, Soviet efforts had been limited by a lack of uranium but new supplies in Eastern Europe were found and provided a steady supply while the Soviets developed a domestic source . While American experts had predicted that the Soviet Union would not have nuclear weapons until the mid-1950s, the first Soviet bomb was detonated on August 29, 1949, shocking the entire world . The bomb, named "First Lightning" by the West, was more or less a copy of "Fat Man", one of the bombs the United States had dropped on Japan in 1945 . </P> <P> Both governments spent massive amounts to increase the quality and quantity of their nuclear arsenals . Both nations quickly began the development of a hydrogen bomb and the United States detonated the first hydrogen bomb on November 1, 1952, on Enewetak, an atoll in the Pacific Ocean . Code - named "Ivy Mike", the project was led by Edward Teller, a Hungarian - American nuclear physicist . It created a cloud 100 miles wide and 25 miles high, killing all life on the surrounding islands . Again, the Soviets surprised the world by exploding a deployable thermonuclear device in August 1953 although it was not a true multi-stage hydrogen bomb . However, it was small enough to be dropped from an airplane, making it ready for use . The development of these two Soviet bombs was greatly aided by the Russian spies Harry Gold and Klaus Fuchs . </P> <P> On March 1, 1954, the U.S. conducted the Castle Bravo test, which tested another hydrogen bomb on Bikini Atoll . Scientists significantly underestimated the size of the bomb, thinking it would yield 5 megatons . However, it yielded 14.8 megatons, which is the largest nuclear explosion tested by the U.S. The explosion was so large the nuclear fallout exposed residents up to 300 miles away to significant amounts of radiation . They were eventually evacuated, but most of them experienced radiation poisoning and resulted in one death from a crew member of a fishing boat 90 miles from the explosion . </P>

Explain how the us and the soviet union used nuclear weapons as a form of deterrence