History in your hands... literally.
J. Robert Oppenheimer, met with Truman in the oval office, after the end of the war.
He tried to convince Truman, that we (usa) needed to slow down the progression of nuclear weapons... after the Japan A bombings.
Truman basically stopped the conversation, and kicked him out, after that.
Oppenheimer, had regrets for what he was in charge of developing, after seeing the total annihilation in Japan, knowing that other countries... (Soviet Union in 1949) would soon develop their own version of the "Bomb".
The monster had been unleashed, that we, as a world community, are still dealing with today.