Mass killing administered by US military and its allies took place in both Vietnam War and in Korean War, who was held accountable for the killing and for the cover-up, except for may be a few low ranking military personnels? And Oh, history, right!
I am not condemning Americans for this matter. In fact I agree Americans probably are among those who tried harder to prevent mass killing in wars. But, please, no morality and free-press and "I am not like you" crap. In war people just die in massive scale. How they are killed makes little difference.