I stand corrected. For some reason, I thought Oppenheimer was a foreigner.
Robert Oppenheimer’s father was German immigrant.
There have been several foreign or foreign-born top scientists working on or making great contributions to the Manhattan Project - including Albert Einstein (indirectly, to an extent) Enrico Fremi, Emilio Segrè, Niels Bohr, (János) John von Neumann, (Jenó) Eugene Wigner, Edward Teller, Stanislaw Ulam, Josef Rotblat, Leo Szilárd, Hans Albrecht Bethe, just to name a few.
Of course, there was also Klaus Fuchs, but he was a Communist first, German-born Brit second.
The atomic bomb project in Germany, headed by brilliant German physicist Werner Heisenberg (of Heisenberg Uncertainty Principle fame), was not far along because Heisenberg “miscalculated” the amount of uranium needed to make the bomb by orders of magnitude - thus setting their reactor effort back several years, and to the U.S. nuclear program benefit when more than two tons of the German uranium stockpile was taken to Britain and then moved to the U.S.
When it's so easy to google someone...