In America, it was decided to attempt the production of atomic bombs with an effort that would constitute a large part of the collective American war effort. In Germany, an effort one thousandth the scale of the American was applied to the problem of producing atomic energy that would drive engines.

Reports in Washington show that our reasoning was just like that of your physicists. With all this information available, at least to privileged persons, I cannot understand why it is generally held in the United States that we completely missed the basic principle of the bomb until after Hiroshima.

The German physicists knew at least so much about the manufacture and construction of atomic bombs that it was clear to them that the manufacture of bombs in Germany could not succeed during the war. For this reason, they were spared the moral decision whether they should make an atomic bomb, and they had only worked on the uranium engine.

Werner Heisenberg Quotes