Peleiu, Iwo Jima, Okinawa, Invading Japan would have been no picnic.

[SidneyCarton]

Starting with Peleiu the Japanese Army switched tactics to oppose the U.S. "Island Hopping" strategy. Instead of massive resistance on the beach in a series of "banzai" charges, they turned to a strategy of attrition, where they held out in the volcanic caves and highlands of these islands, and fought long, grinding delaying campaigns.

Who is to say that such would not have been the case on Kyushu and Honshu, targets of Operations Olympic and Coronet?

Furthermore, those who advocate blockade... Assuming a blockade of Japan was both feasible and workable, what is your position on the decade of sanctions we held on Iraq? If our starvation of a generation of Iraqi children was immoral, would it not have been equally so to do so to the Japanese?

Finally, let us consider the Soviet angle for a moment... By the dropping of the bombs on Hiroshima and Nagasaki, the Soviet Army was already in motion, engaging the Japanese in Manchuria, as well as sweeping down Sakhalin and the Kuriles, toward a possible occupation of Hokkaido and northern Honshu. Considering the fate of other regions occupied by the Soviets in east Asia, there is the possibility that, much like on the Korean peninsula, we would still be maintaining an armed border between a U.S. backed South Japan and a pseudo-Stalinist North?

Hiroshima and Nagasaki were awful events, horrors without true parallel in human history (if for no other reason than that so little ordinance was necessary to cause so much death) They also stand as awful harbingers of the ultimate cost of total war, which is the total annihilation of the human race. Yet the alternatives in August 1945 were by no means marvelous. Did Truman make the wrong decision, maybe. But as the grandson of two men who enlisted in the Navy in 1945, any alternative would have had more than academic consequences for me and my family, as it would have had for the families of countless thousands, if not millions of Americans and Japanese (as well as likely Russians) that were otherwise spared.

http://en.wikipedia.org/wiki/Battle_of_Peleliu
http://en.wikipedia.org/wiki/Battle_of_Iwo_Jima
http://en.wikipedia.org/wiki/Battle_of_Okinawa
http://en.wikipedia.org/wiki/Operation_Downfall

Edited to add reading material