I thought the "rules of war" covered by the Geneva accords were rules agreed upon by nations who are signatory to the accords. It covers combatants who are in the armies of the signatory nations. Combatants are supposed to wear uniforms, among other things. The people the Marines are fighting in Fallujah are not "combatants" according to the Geneva convention. They are not members of a national army that has signed the accords. They are armed terrorists as far as I can tell. They have no status and therefore are not accorded the protections of the convention. Comments?
I don't really care about the Geneva Convention, but your thinking sounds right to me.