Althought I have read a lot of what has been written about the Manhattan Project I am more interested in the science of it than the politics. I think the USA was considering an amphibious assault of Japan and the loss of life would have been totally unacceptable SFAIK. The atomic bomb was used and the loss of life became very one-sided. This probably suited the USA but raises moral questions which are still discussed today; Hiroshima, Nagasaki and Dresden.