Knock off the genocide talk.
Noone is talking genocide, and I apologize if anyone sees it that way.
But it's a valid, historical parallel. In the past, we destroyed cities in Germany and Japan because their rulers were our mortal enemies. Japan was taken over by the Shintoists, a politico-religious movement. We destroyed some of their principal cities in order to win the war on two fronts.
The question is: Would destroying some key cities of under enemy control be an acceptable remedy to this war we face today? Why, or why not?
I believe it is clear that our enemies in this struggle would not hesitate to destroy our cities if they could.