War is never civilized, but in America I think that we have always tried to be as professional about it as possible (with notable exceptions).
Even in WW2 we didn't kill every single Japanese American, we just moved them around so that they would be less of a risk. And in a lot of cases when we get POW's they actually don't mind being an American POW, because they know we will not kill them for any reason.
Also the military has invested heavy amounts of money in munitions that reduce civilian causalities (laser guided bombs are one example).
Also weather or not you agree with the war in Iraq or America's reasons. The Iraq people are better off and in return we get this.
Of course you can bring up situations that could happen but have not happened yet: Civil war and other such things. If you can bring up things that have not happened but could, I can bring things that won't happen but could have happened. They could have developed WMD's and destroyed the whole area.
In a larger sense it is the Islamic culture of revenge that gives birth to these actions. I wonder how the rest of the Islamic world views their brother’s actions.