Not until the day he was sworn in as president after FDR died.
ultimately it was Truman's.
The Manhattan Project
he was surprised but decided to go along with it to protect the country
The project was codenamed "The Manhattan Project" in the United States under the Truman administration.
MacArthur knew nothing about the Manhattan Project until after the bombs were dropped.
The Manhattan Project IS the codename. So no, there is not.
The Manhattan project
Truman authorized the dropping of the bombs.
Truman was not even aware of the existence of the Manhattan project until he became President. There WAS no communication prior to that.
The Manhattan Project.
The atom bomb research and development were conducted under the Manhattan project.
Manhattan Project