I read an article by some guy named Chris Hedges, where he discusses how war in general, and Iraq in particular, can turn a soldier from a killer into a murderer. Of particular note:
The rage soldiers feel after a roadside bomb explodes, killing or maiming their comrades, is one that is easily directed over time to innocent civilians who are seen to support the insurgents. It is a short psychological leap, but a massive moral leap. It is a leap from killing– the shooting of someone who has the capacity to do you harm– to murder– the deadly assault against someone who cannot harm you. The war in Iraq is now primarily about murder. There is very little killing.
He goes on with this blunt assessment of the side of the war we see:
The American killing project is not described in these terms to a distant public. The politicians still speak in the abstract terms of glory, honor, and heroism, in the necessity of improving the world, in lofty phrases of political and spiritual renewal. Those who kill large numbers of people always claim it as a virtue. The campaign to rid the world of terror is expressed with this rhetoric, as if once all terrorists are destroyed evil itself will vanish.
Very true. And very scary.