Kill one person, it's murder
Kill a few more, it's mass murder
Kill a few dozen, it's a "terrorist incident". This is the "grey area". It may become a CNN special presentation or it may just be quickly forgotten, depends entirely upon who is affected. If it's in Africa, it won't be more than a footnote.
Kill hundreds or thousands, it's "legitimate war" - women and children become mere statistics. Holy men pray for victory. Medals and speeches all around. Movie rights. And best of all, the victor writes the history.
The bottom line is that you only get away with murder, if you kill enough people.
We're a very efficient species.
