Atomic bombs were the first nuclear weapons to be developed, tested, and used. In the late 1930s physicists in Europe and the United States realized that the fission of uranium could be used to create an extremely powerful explosive weapon. In August 1939, German-American physicist Albert Einstein sent a letter to U.S. president Franklin D. Roosevelt that described this discovery and warned of its potential development by other nations. The U.S. government established the …showed first 75 words of 1234 total…

…showed last 75 words of 1234 total…