Well, it is done. It seems to me that if this weren't an effective tactic, it probably would have gone the way of the dodo. Attacking civilians has for millennia been a part of warfare. In WW2 the civilian populations on both sides were seen as fair game, insofar as the military machine was ultimately backed up by a civilian population. Al Qaeda had a policy of attacking only military targets until a fatwa was issued calling for attacks on civilians, as they "backed up" this military.

WHat if the civilians are the enemy? In many conflicts, this seems to be the case.