I don't argue that a certain set of protocols have existed in the Western World about things that 'weren't done' because of a longer term realization that as bad as war is, things could be worse with no rules at all. The problem is that the your garden variety Islamic radical has already thrown all those rules out the window with the use of civilian terror, civilian hostages, non-uniformed combatants, human shield warfare, drilling military capability into civilian infrastructure, etc, etc. There is a paradigm in game theory where the best course is to hold to the rules when your adversary first violates them, but if the behavior continues, you win by meeting fire with fire. The US has pretty much always followed that course in wartime, so we are in no position to criticize Israel for doing the same.