“The atomic bomb is too dangerous to be loose in a lawless world.”

Report on the Potsdam Conference (1945)
Context: The world will note that the first atomic bomb was dropped on Hiroshima, a military base. That was because we wished in this first attack to avoid, insofar as possible, the killing of civilians. But that attack is only a warning of things to come. If Japan does not surrender, bombs will have to be dropped on her war industries and, unfortunately, thousands of civilian lives will be lost. I urge Japanese civilians to leave industrial cities immediately, and save themselves from destruction.

Responding to President George W. Bush remarks on Iran, November 21, 2007 https://www.reuters.com/article/us-venezuela-chavez-bush/chavez-says-bush-belongs-in-asylum-for-ww3-comment-idUSL2062324220071120
2007

The Awakening of Humanity (2008)

Statement about Julius and Ethel Rosenberg having performed espionage for the Soviet Union, as quoted in The FBI-KGB War : A Special Agent's Story (1995), by Robert J. Lamphere and Tom Shachtman, p. 306
Context: Someone helped us a lot with the atomic bomb. The intelligence (service) played a huge role. These Rosenbergs suffered in America. It is not excluded that they helped us. But we shouldn't really speak about it, because we might receive this kind of help in the future.

Announcing the Bombing of Hiroshima (1945)

On the issue of nuclear weapons, in England Their England : Monsters, Maniacs and Moore (1987) http://www.youtube.com/watch?v=Hv44V4d_fDQ
Context: It doesn’t even matter if we ever fire these missiles or not. They are having their effect upon us because there is a generation growing up now who cannot see past the final exclamation mark of a mushroom cloud. They are a generation who can see no moral values that do not end in a crackling crater somewhere. I’m not saying that nuclear bombs are at the root of all of it, but I think it is very, very naïve to assume that you can expose the entire population of the world to the threat of being turned to cinders without them starting to act, perhaps, a little oddly.
I believe in some sort of strange fashion that the presence of the atom bomb might almost be forcing a level of human development that wouldn’t have occurred without the presence of the atom bomb. Maybe this degree of terror will force changes in human attitudes that could not have occurred without the presence of these awful, destructive things. Perhaps we are faced with a race between the Four Horseman of the Apocalypse in one line and the 7th Cavalry in the other. We have not got an awful lot of mid ground between Utopia and Apocalypse, and if somehow our children ever see the day in which it is announced that we do not have these weapons any more, and that we can no longer destroy ourselves and that we’ve got to do something else to do with our time than they will have the right to throw up their arms, let down their streamers and let forth a resounding cheer.

King's comment to Commander Whitehill on July 4, 1950, which was transcribed in Whitehill's notes. As quoted in The Decision to Use the Atomic Bomb and the Architecture of an American Myth (1995) by Gar Alperovitz, p. 321

Source: 1950s, Human Society in Ethics and Politics (1954), p. 47
Context: Suppose atomic bombs had reduced the population of the world to one brother and one sister, should they let the human race die out? I do not know the answer, but I do not think it can be in the affirmative merely on the ground that incest is wicked.