American cover-up of Japanese war crimes

The occupying United States government undertook the selective cover-up of some Japanese war crimes after the end of World War II in Asia, granting political immunity to military personnel who had engaged in human experimentation and other crimes against humanity, predominantly in mainland China. The pardon of Japanese war criminals, among whom were Unit 731's commanding officers General Shirō Ishii and General Masaji Kitano, was overseen by General of the Army Douglas MacArthur in September 1945.

Source: Wikipedia — American cover-up of Japanese war crimes (CC BY-SA 4.0)