The saga of Unit 731 and how they received zero punitive action is just one of the several horridly fucked-up things that came out of the end of the Second World War, and how both the Western Allies and the Soviets cleaned up afterwards.
The Soviet Union and the United States gathered data and evidence from the Unit after the fall of Japan. While twelve Unit 731 researchers arrested by Soviet forces were tried at the December 1949 Khabarovsk war crimes trials, they were sentenced only to the Siberian labor camp from 2 to 25 years, seemingly in exchange for the information they held.[1] Those captured by the US military were secretly given immunity,[2] while being covered up with stipends to the perpetrators. The US was purported to have co-opted the researchers’ bioweapons information and experience for use in their own warfare program (resembling Operation Paperclip), and so did the Soviet Union in building their bioweapons facility in Sverdlovsk using documentation captured from the Unit in Manchuria.[1][3][4] In 1956, those still serving their sentences were released and repatriated to Japan.
The saga of Unit 731 and how they received zero punitive action is just one of the several horridly fucked-up things that came out of the end of the Second World War, and how both the Western Allies and the Soviets cleaned up afterwards.
https://en.wikipedia.org/wiki/Khabarovsk_war_crimes_trials