Clearly there was war in scripture (from where I draw my personal morality), however, ordained by God. Ron Paul clearly demonstrates that most wars are not holy, or just, or produce anything good. Answers my questions about how atrocities like "incident on hill 192" and the "My Lai Massacre" in just Vietnam can happen. When there are no real answers for all this killing (I would turn into a monster too) the morally damaged conscience can cause a world of hurt. They aren't robots, they are men with consciences.
I.e. Please read this book.
Here is a review.