Sorry for taking so long to reply!

Those of you wishing to believe that the Japanese might have surrendered in any other circumstances than post-The Bomb(s) are living in cloud cuckoo land. Prime Minister Suzuki stated that, without the atomic bombs, Japan would not have surrendered (& he ought to know).

Russian invasion made no bloody difference. The Japanese didn't know what had happened in Manchuria for several days, & didn't care anyway. They'd already stripped all the first class units out of those armies for home defence. As to the suggestion that Russian intervention was a complete & unpleasant surprise... The Japs made a remarkably good job of fortifying Maritime Province (Far East - Vladivostock way) in anticipation of such an event. Such that the projected 9th August invasion of Hokkaido would have been at least a fortnight behind schedule, due to the tenacious resistance of Japanese forces, especially on Sakhalin (an important staging post for the Soviets).

Economic collapse meant nothing, & blockade would not have affected the "Big Six" that ruled Japan. Millions would have died from starvation in Japan (including all Allied POW's & internees), which would not have affected Japanese determination in the least. They were dying for their God.

The entire Japanese strategy was to win the "decisive battle". Not "decisive" in any military sense, but to make the cost of any Allied victory so high as to make negotation (acceptance of Japanese terms, in other words) preferable. This had been High Command strategy for many months.

The advent of nuclear war, as Suzuki admitted, made an invasion of Japan redundant. At that point, given that they didn't (& couldn't possibly) know that there were only two bombs, the only strategy remaining was national suicide. Even then, it took unprecedented intervention from the Emperor to initiate surrender. God knows what would have happened if Japan had bluffed for a week or two. The longer it went without the USA obliging with a third bomb...

Fact: there is no pre-Hiroshima document from Japan that suggests that any terms that Japan might have considered were at all acceptable to the Allies.

Fact: no Japanese government had surrendered in over 2,000 years.

Fact: no Japanese unit surrendered before 15/8/45. Even after that date, many units refused to believe in the Emperor's surrender, & many (particularly officers) committed suicide rather than shame themselves.

Fact: the first time the Japanese government seriously discussed surrender is the day Fatman fell (I do not know whether this discussion took place before, after, or with knowledge of, the Nagasaki bomb). Even then, the Big Six were split 50-50 as to surrender terms.

History Lesson: The Political Reality of Japan

Japan was ruled by an Imperial Council, colloquially known as the Big Six. In the twenty-odd years preceding 1945 there are no less than 64 assorted purges, including 2 prime ministerial assassinations. No-one is going to say "Boo" to the Big Six in 1945, gentlemen. Not no way, not no how. The only attempt at a coup in war years is post-surrender & an attempt to continue the war!!! As, I think, Hawk has already pointed out.

For the 'Six' to function, they must be unanimous (it is, if you will, a variation on the Shogun governments that plagued a slightly earlier Japan). Of the 6 members, only one (the Foreign Minister) is a civilian. Of the remaining 5, one is a retired Admiral (I think this is Suzuki, the PM, retired 1937), the rest are serving Flag Officers. Japan is firmly in the hand of militarists.

Even on the day of Fatman, the discussion is split equally between two camps. Both are conditional surrenders. Condition one (common to both) is that the Imperial system must continue. Conditions two through four are: Repatriation of all Japanese combatants; all "so-called war crimes trials" Japanese wording! to be conducted under Japanese supervision; no Allied occupation of Japan. Because of the split, the official position will be that of the "all four conditions" party.

Hirohito made an unprecedented intervention at this point. The surrender was offered with only condition one as a rider. The US Sec. of State responded swiftly - only unconditional surrender was acceptable & the Emperor was to be subject to the Supreme Allied Commander. More heated discussion ensued in the Japanese cabinet, but on 14/8/45 the Emperor made a unilateral decision. Radio messages were sent to all Japanese armies, & at noon 15/8/45 many Japanese heard the voice of their god for the very first time as he declared the surrneder...

Now don't drop The Bomb...

The Imperial High Command are already seriously considering declaring martial law. Invasion by any of the Allies will certainly trigger this. At this point, Hirohito no longer has an mechanism by which he can intervene. His power is entirely based on the willingness of the government & military to obey him. Take away the Big Six, & there is zero chance that any such opportunity will occur. Moreover, the infrastructure to communicate a surrender would have disintegrated before Hirohito had a chance to announce it.

Fact: Before Fat Boy, the US General in charge of bombing operations over Japan had already decided to change focus. In light of the German/European experience, he had given orders to target communications & infrastructure, instead of cities. Japanese infrastructure is incredibly vulnerable. Keeping the rail network cut in just half-a-dozen or so places (given that their maritime transport network is, in the current circumstances, at a complete standstill) will result in the the civilian (not military - betcha they'll get fed?) starvation of the south.

Fact: In post-war Japan, even with the nuclear-induced victory of the Allies, the ration was cut as low as 1,040 calories/day. Imagine what Japan would have been in the wake of a protacted conventional campaign...

Congratulations to the morally upright amongst you who would not have dropped The Bomb. Conservative estimates suggest you will kill around 5 million Japanese through military intervention & starvation, & 5-10 million others before the war ends. The war will last another 2-5 years. Japan (without substantial economic help) will remain an agricutural backwater. Of course, the Marshall Plan for Western Europe probably won't happen because resources will be lacking, & so on & so forth...

You've just made the world a better place, haven't you... (I'm glad you think Truman was a cold-hearted, gullible, evil, whatever-adjective-you-like bastard - Me? I prefer to think of him as a pragmatist. He didn't choose a good choice, cos there weren't any. He chose the best one he could find, & I reckon history won't judge him too badly whatever the nay-sayers may claim)