In the ruined German city of Potsdam, six thousand miles from occupied Southeast Asia, American President Truman had something important to tell his Soviet counterpart: ‘On July 24 I casually mentioned to Stalin that we had a new weapon of unusual destructive force. The Russian Premier showed no special interest. All he said was that he was glad to hear it and hoped we would make 'good use of it against the Japanese.'’ His apparent indifference to the new American weapon was, of course, a sham. Stalin had already made plans to abandon the ‘Neutrality Pact’ signed in 1941 and join the war against Japan. He had in fact promised to ‘come in’ two years earlier at the Tehran Conference. At the same time, Soviet diplomats continued to hold out the possibility that they would help mediate in negotiations to end the war and save Japanese face. This was the principal reason why the Emperor was so reluctant to consider unconditional surrender terms. Soviet strategy was pure Machiavelli. Behind the smoke and mirrors of Potsdam, the United States and the Soviet Union maneuvered to control events in the Far East for their own ends. The chronology is revealing. On 6 August, the first atomic bomb ‘Little Boy’ exploded above the city of Hiroshima. On 8 August, the Soviet Foreign Minister Vyacheslav Molotov informed his Japanese counterpart that the Soviet Union declared war on Japan. The following day, ‘Fat Man’, a more powerful implosion bomb fell on Nagasaki and Soviet troops commanded by Marshal Aleksandr Vasilevsky marched into Japanese occupied Manchuria (Manchukuo) on three fronts. In the United States, plans were made to assemble and deliver more ‘Fat Man’ weapons to attack Japan.
Historian TsuyoshiHasegawa has convincingly argued that it was the Soviet intervention that played the greater role inducing Emperor Hirohito to surrender. Stalin was an active, indeed aggressive, participant not a secondary player in the drama of the Japanese surrender. Three months after the defeat of Nazi Germany, the world’s two superpowers were jockeying for position on a global scale. It was the interlaced shockwaves of the atomic bombs and the Soviet attack persuaded Emperor Hirohito on 14 August to decide, despite the threat of a coup d’etat by a ‘war party’, that Japan had run out of options and must capitulate. He insisted on one condition - that the declaration would acknowledge ‘the prerogatives of His Majesty as a Sovereign ruler.’ According to Japan’s Meiji Constitution of 1889, the Emperor was ‘sacred and inviolable’: this principle of ‘Kokutai’ would have to be respected. Hirohito confided to his uncle Prince Asaka that if the Allies refused to accept this condition, Japan would have no choice but to fight on.
The Emperor’s notorious broadcast made on 15 August was a slippery and devious acceptance of defeat. The ‘Imperial Rescript’ as it was called admitted that the war situation had ‘not developed necessarily to Nippon’s advantage.’ The Emperor defended the war as the expression of a ‘sincere desire to ensure Nippon’s self-preservation and the stabilisation of East Asia’. As it turned out, the Americans appreciated the political value of upholding the Emperor’s sovereign status. In Tokyo, the ‘war party’ had been preparing for a ‘kamikaze’ last ditch defence of the homeland. The Americans would exploit the Emperor’s semi divine status to enforce compliance. After 1945, Hirohito would assume the same kind of role under American occupation that the Japanese had allotted to the last Chinese emperor Pu Yi when he was appointed ‘ruler’ of the puppet state of Manchukuo in 1932.