Offical Japanese Intelligence PDF

The Manchurian Strategic Offensive Operation, along with the two atomic bombings of Hiroshima and Nagasaki, combined to break the Japanese political deadlock and force Japan's surrender; they made it clear that Japan had no hope of holding out, even in the Home Islands.

Japan's decision to surrender was made before the scale of the Soviet attack on Manchuria, Sakhalin, and the Kurils was known[9], but had the war continued, the Soviets had plans to invade Hokkaidō well before the other Allied invasion of Kyushu.[10][11]

Tsuyoshi Hasegawa's research has led him to conclude that the atomic bombings were not the principal reason for capitulation. Instead, he contends, it was the swift and devastating Soviet victories on the mainland in the week following Joseph Stalin's August 8 declaration of war that forced the Japanese message of surrender on August 15, 1945.[12] His claim, however, has been criticized because it ignores the fact that the Imperial Headquarters in Tokyo was unaware of how badly the fighting in Manchuria was going.[13]

Manchuria, cleansed of any potential military resistance by Soviet forces, provided the main base of operations for Mao Zedong's forces, who proved victorious in the following four years of civil war in China. In fact, military success in Manchuria prevented the Soviet Union from receiving bases in China — promised by the Western Allies — because all land gained was turned over to the People's Republic of China after they gained power. Before leaving Manchuria, however, Soviet forces dismantled its considerable industry and relocated it to restore industry in war-torn Soviet territory.

As agreed at Yalta, the Soviet Union had intervened in the war with Japan within three months of the German surrender, and they were therefore entitled to the territories of Sakhalin and the Kuril Islands and also to preeminent interests over Port Arthur and Dairen, with its strategic rail connections. The territories on the Asian mainland were transferred to the full control of the People's Republic of China in 1955, and the other possessions are still administered by the Soviet Union's successor state, Russia. Though the north of the Korean peninsula was under Soviet control, the logistic machine driving the invasion forces had given out before the entire peninsula could be seized. With the American landing at Incheon — some time before the Red Army could have remobilized and secured the entire nation — Korea was effectively divided. This was a precursor to the Korean War five years later.