After the war, it turned out that the Nazis weren't even working on a nuclear bomb. So had the US not done it, nobody might have. Other nuclear powers did it only because the US had them and had shown that it was possible.
> Nazi Germany undertook several research programs relating to nuclear technology, including nuclear weapons and nuclear reactors, before and during World War II. [...] The first effort started in April 1939, just months after the discovery of nuclear fission in Berlin in December 1938, but ended shortly ahead of the September 1939 German invasion of Poland, for which many German physicists were drafted into the Wehrmacht. A second effort under the administrative purview of the Wehrmacht's Heereswaffenamt began on September 1, 1939, the day of the invasion of Poland. The program eventually expanded into three main efforts: Uranmaschine (nuclear reactor) development, uranium and heavy water production, and uranium isotope separation. Eventually, the German military determined that nuclear fission would not contribute significantly to the war, and in January 1942 the Heereswaffenamt turned the program over to the Reich Research Council (Reichsforschungsrat) while continuing to fund the activity.
> The program was split up among nine major institutes where the directors dominated research and set their own objectives. Subsequently, the number of scientists working on applied nuclear fission began to diminish as many researchers applied their talents to more pressing wartime demands.
> [...] Heisenberg said that in 1939, the physicists at this second meeting concluded that "in principle atomic bombs could be made, but they also emphasized that it would take a number of years",[24] certainly not less than five. He also said that he "didn't report it to the Führer until two weeks later and very casually because I did not want the Führer to get so interested that he would order great efforts immediately to make the atomic bomb. Speer felt it was better that the whole thing should be dropped and the Führer also reacted that way."
> [...] Speer states that the project to develop the atom bomb was scuttled in the autumn of 1942. Though the scientific solution was there, it would have taken all of Germany's production resources to produce a bomb, and then no sooner than 1947.[39] Development did continue with a "uranium motor" for the navy and development of a German cyclotron. However, by the summer of 1943, Speer released the remaining 1200 metric tons of uranium stock for the production of solid-core ammunition.
There are ways of calling this "weren't working on a nuclear bomb", but it seems to me like "they wanted to, were moving in that direction, and would have done it if they had the resources and weren't distracted by shorter-term considerations".
https://en.wikipedia.org/wiki/German_nuclear_program_during_...
> Nazi Germany undertook several research programs relating to nuclear technology, including nuclear weapons and nuclear reactors, before and during World War II. [...] The first effort started in April 1939, just months after the discovery of nuclear fission in Berlin in December 1938, but ended shortly ahead of the September 1939 German invasion of Poland, for which many German physicists were drafted into the Wehrmacht. A second effort under the administrative purview of the Wehrmacht's Heereswaffenamt began on September 1, 1939, the day of the invasion of Poland. The program eventually expanded into three main efforts: Uranmaschine (nuclear reactor) development, uranium and heavy water production, and uranium isotope separation. Eventually, the German military determined that nuclear fission would not contribute significantly to the war, and in January 1942 the Heereswaffenamt turned the program over to the Reich Research Council (Reichsforschungsrat) while continuing to fund the activity.
> The program was split up among nine major institutes where the directors dominated research and set their own objectives. Subsequently, the number of scientists working on applied nuclear fission began to diminish as many researchers applied their talents to more pressing wartime demands.
> [...] Heisenberg said that in 1939, the physicists at this second meeting concluded that "in principle atomic bombs could be made, but they also emphasized that it would take a number of years",[24] certainly not less than five. He also said that he "didn't report it to the Führer until two weeks later and very casually because I did not want the Führer to get so interested that he would order great efforts immediately to make the atomic bomb. Speer felt it was better that the whole thing should be dropped and the Führer also reacted that way."
> [...] Speer states that the project to develop the atom bomb was scuttled in the autumn of 1942. Though the scientific solution was there, it would have taken all of Germany's production resources to produce a bomb, and then no sooner than 1947.[39] Development did continue with a "uranium motor" for the navy and development of a German cyclotron. However, by the summer of 1943, Speer released the remaining 1200 metric tons of uranium stock for the production of solid-core ammunition.
There are ways of calling this "weren't working on a nuclear bomb", but it seems to me like "they wanted to, were moving in that direction, and would have done it if they had the resources and weren't distracted by shorter-term considerations".