(One of many reasons why, to be exact.)
Warning:
Contains descriptions of rape, massacres, torture, and other atrocities.
ETA: Replaced the URL. For unknown reasons (most likely linking to libgen, but it might have been a copyright violation or the content simply being disturbing), Imgur deleted my album.
The same thing happened here on Brasil during the dictatorship, thousands where brutally tortured, and there is proff that the torturers where trained by the US, who also got the torture techniques from japanese soldiers. They used more then 300 torture techniques.