With an enduring passion for the preservation of human life and political freedom, Szilard hoped that the U.S. government would not use nuclear weapons, but that the mere threat of such weapons would force Germany and Japan to surrender. He also worried about the long-term implications of nuclear weapons, predicting that their use by the United States would start a nuclear arms race with the USSR. He drafted the Szilárd petition advocating that the atomic bomb be demonstrated to the enemy, and used only if the enemy did not then surrender. The Interim Committee instead chose to use atomic bombs against cities over the protests of Szilard and other scientists. Afterwards, he lobbied for amendments to the Atomic Energy Act of 1946 that placed nuclear energy under civilian control.