“The atomic bomb played no decisive part, from a purely military standpoint, in the defeat of Japan.”

1960s, Beyond Vietnam: A Time to Break Silence (1967)
Context: War is not the answer. Communism will never be defeated by the use of atomic bombs or nuclear weapons. Let us not join those who shout war and, through their misguided passions, urge the United States to relinquish its participation in the United Nations. These are days which demand wise restraint and calm reasonableness. We must not engage in a negative anticommunism, but rather in a positive thrust for democracy, realizing that our greatest defense against communism is to take offensive action in behalf of justice. We must with positive action seek to remove those conditions of poverty, insecurity, and injustice, which are the fertile soil in which the seed of communism grows and develops.

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

April 25, 2006
The Areas of My Expertise (2005), Appearances on The Daily Show with Jon Stewart

The Irony of American History (1952)

1950s, Farewell address to Congress (1951)

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.

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.

The Secretary was deeply perturbed by my attitude...
The White House Years: Mandate for Change: 1953–1956: A Personal Account (1963), pp. 312-313
1960s

Report on the Potsdam Conference (1945)
Context: The atomic bomb is too dangerous to be loose in a lawless world. That is why Great Britain, Canada, and the United States, who have the secret of its production, do not intend to reveal that secret until means have been found to control the bomb so as to protect ourselves and the rest of the world from the danger of total destruction.