It’s also defensible to say, as Eisenhower did, that their defeat was inevitable. the blockade of Japan was already having a mammoth toll.
Indeed. Allied victory was actually inevitable from December 8, 1941.
However, Japanese civilians of the day were also being trained to defend their homes with bamboo spears. Defeat may have been inevitable but the means for achieving that defeat had yet to be found.
So how would it have happened? A blockade of Japan, with ensuing mass starvation? Invasion, to end the war and return America’s citizen soldiers to their regular lives at huge human cost? Or a way to end the war, however cruel it appeared, through projection of irrefutably awesome power?
That was Truman’s choice.