The Manhattan Project was inaugurated to respond to the perceived threat that Nazi Germany would develop weapons based on atomic energy, which they would deploy without qualms against the Allied countries. allowed the United States to produce and deploy the world`s first atomic bomb at Hiroshima in August, 1945. The United States hoped, at the conclusion of World War II, that it would be able to maintain sole knowledge of and control over atomic weapons. This illusion was shattered on August 29, 1949, when the Soviet Union exploded an atomic bomb of its own. The USSR may have been aided in this speedy development by spies, such as the Rosenbergs.
The next step was the hydrogen bomb. The concept had been proposed during World War II, but the United States had declined to pursue it following the end of the war. After, the Soviet explosion of an atomic weapon, however, Harry Truman gave the go-ahead to develop the H-Bomb. Again, the United States was first to conduct a successful test, on November 1, 1952, in the Marshall Islands. Again, the Soviet Union followed, this time more closely, with a test explosiion on August 12, 1953.
With both countries now possessing the Super Bomb, the emphasis shifted to delivery systems. The United States deployed the Strategic Air Command (SAC), which had airplanes in the air at all times ready to deliver a response to any Soviet attack without requiring planes to become airborne.
With the development of Intercontinental Ballistic Missiles, or ICBMs, the time available to correct a misunderstanding shrank still futher and both sides of the Cold War recognized the need to step back from the precipice. The first treaty, banning above-ground tests of nuclear weapons, was signed in Moscow on August 5, 1963. Later, the Strategic Arms Limitation Talks (SALT) resulted in agreements to further reduce arms.
The two superpowers have cooperated in the ensuing years in reducing their nuclear arsenals. The problem has been complicated, however, by the addition of a number of nations to the nuclear family, including definitely China, India, and Pakistan. Israel problem has nuclear weapons and Iran may be planning to develop them.