The Japanese experimentally killed about 3,000 people - including American prisoners of war - in World War II, according to a Washington Post story based on an article in the Bulletin of Atomic Scientists. The article says the US military establishment made a secret arrangement with the Japanese to hide the experiments.
The United States agreed to grant immunity from War crimes prosecution to Japanese officers involved in exchange for being able to use the results from the tests. The victims were used as experimental animals, and were eventually killed with enormous doses of germs or radiation poisoning or in other grotesque ways.
Official records obtained by the article's author, John Powell, indicated that the bargainmaking Americans were aware that US soldiers were being killed in the experiments.