<P> Japan 's geography made this invasion plan quite obvious to the Japanese as well ; they were able to predict the Allied invasion plans accurately and thus adjust their defensive plan , Operation Ketsugō , accordingly . The Japanese planned an all - out defense of Kyūshū , with little left in reserve for any subsequent defense operations . Casualty predictions varied widely , but were extremely high . Depending on the degree to which Japanese civilians would have resisted the invasion , estimates ran up into the millions for Allied casualties . </P>
how many american casualties were predicted during the planning for the invasion of japan
Casualty predictions varied widely , but were extremely high estimates ran up into the millions for Allied casualties