Japanese in WWII were no different. We didn't need to kill all of them either. It's just that we got the message across to them that we were prepared to kill all of them if that's what it took.
That's correct.
What do you do to someone who is willing to DIE to kill you? You must kill them FIRST.
Of course, we can't go around killing all of the Muslims in America. But we can "level" one or more of these nations. They will get the picture. That we are serious about killing them off. They will quiet down for a while.