Nuclear arms race

The nuclear arms race was a competition for supremacy in nuclear warfare between the United States, the Soviet Union, and their respective allies during the Cold War. During this period, in addition to the American and Soviet nuclear stockpiles, other countries developed nuclear weapons, though none engaged in warhead production on nearly the same scale as the two superpowers.

The first nuclear weapon was created by the U.S. during the Second World War and was developed to be used against the Axis powers. Scientists of the Soviet Union were aware of the potential of nuclear weapons and had also been conducting research on the field.

The Soviet Union was not informed officially of the Manhattan Project until Stalin was briefed at the Potsdam Conference on July 24, 1945, by U.S. President Harry S. Truman, eight days after the first successful test of a nuclear weapon. Despite their wartime military alliance, the United States and Britain had not trusted the Soviets enough to keep knowledge of the Manhattan Project safe from German spies: there were also concerns that, as an ally, the Soviet Union would request and expect to receive technical details of the new weapon.

When President Truman informed Stalin of the weapons, he was surprised at how calmly Stalin reacted to the news and thought that Stalin had not understood what he had been told. Other members of the United States and British delegations who closely observed the exchange formed the same conclusion.

In fact Stalin had long been aware of the program, despite the Manhattan Project having a secret classification so high that, even as Vice President, Truman did not know about it or the development of the weapons (Truman was not informed until shortly after he became president). A ring of spies operating within the Manhattan Project, (including Klaus Fuchs and Theodore Hall) had kept Stalin well informed of American progress. They provided the Soviets with detailed designs of the implosion bomb and the hydrogen bomb. Fuchs' arrest in 1950 led to the arrests of many other Russian spies, including Harry Gold, David Greenglass, and Ethel and Julius Rosenberg.

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