Edward Teller was trained as a physical chemist at the University of Leipzig, receiving a doctorate in 1930. When the Nazis came to power in Germany, Teller left for the United States, where he worked on the Manhattan Project developing the atomic bomb. His own interest, however, was in the development of the hydrogen bomb, and he is widely considered the father of the H-bomb. Following World War II, Teller took the hard-line posture that American nuclear supremacy was essential to limiting Soviet arms intentions. Teller was opposed to the ratification of the Nuclear Test Ban Treaty on the grounds that policing the agreement would be difficult and that it limited further development of antiballistic missiles in which he believed the Soviets already had the edge.