To quote Oppenheimer in his farewell speech to the Association of Los Alamos Scientists:
"It may be helpful to think a little of what people said and felt of their motives in coming into this job ... There was in the first place the great concern that our enemy might develop these weapons before we did, and the feeling ... that without atomic weapons it might be very difficult, it might be an impossible, it might be an incredibly long thing to win the war ... Some people, I think, were motivated by curiosity, and rightly so; and some by a sense of adventure, and rightly so. Others had more political arguments ... And there was finally, and I think rightly, the feeling that there was probably no place in the world where the development of atomic weapons would have a better chance of leading to a reasonable solution, and a smaller chance of leading to disaster, than within the United States. I believe all these things that people said are true, and I think I said them all myself at one time or another."