Question

why was the manhattan project kept top secret?

The United States did not want Great Britain or France to know that it had nuclear technology.

No one was sure if the atom bomb would actually ever work and they didn't want negative feedback.

The Allies were afraid that the technology would be stolen by spies belonging to Germany or Japan.

The United States was developing the technology illegally and with stolen technology and materials.

Answer 1

i think No one was sure if the atom bomb would actually ever work and they didn't want negative feedback.

Answer 2

if correct please click best response.

Answer 3

Actually in this case, I'd say that the Allies were afraid the tech would be stolen by spies. At the time, the US and the physicists involved -- many of whom had fled Germany -- believed that the Nazis were close to building their own atomic bomb and feared what would happen if they got it first. And since the Japanese were allied to Germany, they were also concerned about any technical information shared between them.

When the Nazis were crushed, the US got a good look at their nuclear program and discovered that they were actually far behind them. They had the basics down, but their nuclear program was still in its infancy compared to how far the Americans had come. What was probably more valuable were the stocks of uranium that the Nazis seized from other nations, uranium that could be used in the US program.