The occupying United States government undertook the selectivecover-up of someJapanese war crimes after theend of World War II in Asia, granting political immunity to military personnel who had engaged inhuman experimentation and othercrimes against humanity, predominantly inmainland China.[1][2] Thepardon of Japanese war criminals, among whom wereUnit 731's commanding officers GeneralShirō Ishii and GeneralMasaji Kitano, was overseen byGeneral of the ArmyDouglas MacArthur in September 1945. While a series of wartribunals and trials was organized, many of the high-ranking officials and doctors who devised and respectively performed the experiments were pardoned and never brought to justice due to the US government both classifying incriminating evidence, as well as blocking the prosecution access to key witnesses.[3] As many as 12,000 people, most of them Chinese, died in Unit 731 alone and many more died in other facilities, such asUnit 100 and in field experiments throughoutManchuria.[4][5]
The American government sent GeneralMacArthur to oversee rebuildingpost-war Japan and the shift to ademocracy from a previouslyauthoritarian system of governance. During the occupation, MacArthur assigned Lieutenant ColonelMurray Sanders to gather data on Japan's biological warfare, which was obtained throughhuman experimentation. At Sanders' suggestion, MacArthur offered full political immunity to high-ranking officials who were instrumental in perpetrating crimes against humanity, in exchange for the data about their experiments. Among those wasShirō Ishii, the commander ofUnit 731. During the cover-up operation, the U.S. government paid money to obtain data on human experiments conducted in China, according to two declassified U.S. government documents.[6]
The total amount paid to unnamed former members of the infamous unit was somewhere between 150,000 yen to 200,000 yen. An amount of 200,000 yen at that time is the equivalent of 20 million yen to 40 million yen today.[7]
Japan's emperorHirohito gave his consent regarding the policies and activities ofUnit 731,Unit 100 and other human experimentation facilities.[citation needed] Though it is unclear on whether Emperor Hirohito was made aware of the full extent of Unit 731, the emperor's younger brother,Prince Mikasa, had toured the headquarters of Unit 731 and wrote in his memoirs that he watched films of how Chinese prisoners were "made to march on the plains of Manchuria forpoison gas experiments on humans."[8]
MacArthur, abiding by thePotsdam Declaration, gathered a jury for theTokyo trials, where a number of Japanese officials were successfully tried and convicted.[9] In 1981, one of the last surviving members of the Tokyo Tribunal, JudgeBert Röling, expressed his unhappiness that the war crimes committed in Unit 731 had been protected by the US government and wrote, "It is a bitter experience for me to be informed now that centrally ordered Japanese war criminality of the most disgusting kind was kept secret from the court by the U.S. government."[10]
American POWs returning home from Japanese custody were told not to discuss their experiences with the media or anyone who was not cleared by the military.[11]: 145
