I think it would be useful to consider the enemy's perspective on your statement and question. I'm not sure, but I suspect that they'd question our insistence that our actions in their part of the world are justified, either by natural law or by our religious beliefs (as diverse as they may be). They'd refer to their people dying at the hands of forces that they'd claim we control, and would expect us to offer them an answer to the question you ask with regard to their actions about our own actions. They'd consider their actions far less barbarous than our actions.
I'd disagree with them, and would find our actions utterly defensible. However, looking at it through their point-of-view may help folks better understand why things like this happen, and perhaps understand why addressing the issue from the standpoint of "How can we make them realize they're bad people?" won't be effective.
