Why did president roosevelt originally authorize the development of the atomic bomb? he believed that germany was trying to develop one. he wanted to end the war quickly. he feared that the united states could not defeat japan without it.

The correct answer is He believed that Germany was trying to develop one

Many of the scientists who worked on the project were actually originally German scientists who were saved from the Nazis and taken back to the United States. The US knew that Germany was working on developing atomic weaponry so they needed to make their own in order to protect themselves.