The whole idea of international control of nuclear weapons really originated with Niels Bohr. Niels Bohr was in a unique position because he was Danish, he was essentially neutral, and still was able to go to Los Alamos during the war and see what was going on. He was the only person who wasn't officially cleared but who actually knew what was happening. He was tolerated by the United States government. It was a remarkable piece of wisdom, in a way, that they let him in.
Anyhow, Niels Bohr was already in 1944 campaigning for international control of weapons. He went and he actually got to see Churchill and he got to see Roosevelt, and he told both of them that you have to have international control if this thing was not to destroy the world. Neither of them listened, of course. Churchill in particular considered that Niels Bohr was dangerous, that he was going to go to the Russians and tell them what was happening, so he wanted to have him locked up. That was a tragedy.
Oppenheimer then talked a lot with Bohr during those times. He was right there at Los Alamos. Bohr and Oppenheimer were very close. Oppenheimer's campaign for international control was really just putting Bohr's ideas into practice. Afterwards, Bohr openly campaigned for international control himself. He wrote an open letter to the United Nations called "The Open World," which I think is a really great piece of writing. It's typical Bohr. He always took immense trouble with anything he wrote, so it comes out extremely complicated, but it's a beautiful piece. It's arguing that the essential thing for the survival of the world with nuclear weapons is openness, and that I think is still true.
Making the weapons illegal is by far the best way of having openness. If they are legal at all, then you have to have secrets which are officially protected. That already gets you into trouble. By having this illegal status for the weapons, you can then make it compulsory, according to international law, also to be open, that you have to tell what you have. That's roughly the way Bohr was arguing. I don't think Bohr ever supported the Soviet proposal position, but he came close, certainly closer than we did.