I agree with kidd for most parts. Environment does change people, and many of these soldiers lost conscience under the many influences of leaders who were encouraging them to lose their humanity and act like beasts to the chinese people.
And K2 - you do make a little sense- but seriously its not like their people and citizens in general wanted their troops to torture, put down and do such horrid things to our people. Im sure many of them felt bad, hoped their soldiers would quit such inhumanity and brutalness to innocent beings, and how such acts really provided a horrible reprsentative to them and their country, causing them to be hated by many.