I think we should open dialogue, and before people jump on me, this is exactly the mistake we made with the taliban. They rules for a decade, and there was nothing anyone was going to do to stop them. Instead of opening working relations, we let them harass and kill their people for several years. A ISIS Iraq is still Iraq, whether or not its a republic. Not recognizing an extreme state is only enabling them to be extreme. Just because we recognize a state, doesn't mean we need to like them.