From When the Shooting Stopped: August 1945, by Barrett Tillman (Osprey, 2022), Kindle pp. 118-120:
The Far East blitz represented the acme of Russian military operations in the Great Patriotic War. An American historian properly described the Manchurian offensive as “a post graduate exercise for Soviet forces, the culmination of a rigorous quality education in combat begun in Western Russia in June 1941.”
Red Army losses in the 25-day campaign were 35,000 overall with 11,000 killed, while naval components added 1,400 casualties. In the Kremlin’s hard-eyed accounting, it was nearly a bloodless conquest of an immense, productive area.
Overall in the Far East, the Soviets captured 594,000 Japanese troops, including 143 generals and 20,000 wounded. Almost certainly the astonishing bag of general officers would not have occurred a month before, suicide being the preference.
Postwar Western figures placed Japanese losses at 674,000 including 84,000 dead. American intelligence estimated that the Soviets captured 2.7 million Japanese, two thirds of them civilians. Eventually some 2.3 million were repatriated to Japan, with 254,000 known dead and 93,000 presumed dead.
Of some 220,000 Japanese farmers established in Manchuria, about 70 percent reportedly perished, including perhaps 80,000 in the severe winter of 1945–46. More than 10,000 were thought killed by outraged Chinese, or had committed suicide. Presumably the surviving 140,000 eventually returned to Japan.
The Russians dismantled much of Manchuria’s industrial plant within three weeks of the war’s end, ceding the territory to the Communist Chinese. Thus, without realizing it, Moscow had set the stage for the next war, only five years downstream.
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In the vacuum attending Japan’s defeat, Soviet forces entered Korea in mid-August, advancing southward to the designated 38th Parallel that would mark the boundary between Soviet and American occupation zones. The Russians lost little time exploiting their control over the area, especially since many Koreans welcomed an end to 40 years of Japanese rule.
In the north, Korea already possessed two military organizations: Kim Il-sung’s guerrilla force and the Korean Volunteer Army headquartered in China. The Soviets established headquarters at Pyongyang and almost immediately founded an air force academy.
Meanwhile, the Americans – thin on the ground in the south – planned to retain many Japanese for continuity of government. The reaction among South Koreans was stridently vocal, leading to a quick reversal by the U.S. administrators. However, frequently they consulted their Japanese counterparts, who naturally recommended Koreans who had cooperated with Tokyo. Two distinct Koreas were emerging and battle lines, however unwittingly, were already drawn for the coming Cold War.