The war is over, God ultimately has final judgment on what happened.
My Cousin was in Chu Lai in late 68-69, he was not with Lt Calley though.
My Father was attached to the Australian troops in WW2. He told me that the Aussies commonly cut ears off of Japanese they killed and hung them from a necklace they made. They were not in a particularly good mood, it was payback for atrocities from P.I. to the Southern Islands.
There is no such thing as “rules of war”. That is just a way to assuage guilt for those who send troops, but who do not get “muddy boots”.