IOW, kill 'em all.
That just ain't gonna fly in America, at least not till after we've lost a city or two to smuggled-in nukes.
Does COIN always work? Of course not. Nothing always works. (Except of course for Roman/Mongol/Nazi methods, if you've got a sufficient superiority of force.) But COIN is the only thing that might work.
You could make the argument that is(or was) the traditional method of the Muslims, and especially the Arabs. Until Saladin rose to power in the 12th Century and instated a more "ecumenical" rule after the 3rd Crusade, the Arabs - as a matter of course - would just kill every man, woman and child they came across when attempting to re-take Jerusalem. The Saracens exemplified this kind of barbaric and unforgiving behavior.
After Saladin's death, things returned to "normal" for the Arabs - back to their more barbaric ways. The Moors were a rather unsavory lot as well. Sure, the Nazi's get all the bad press, but as far as barbarism goes, they're in plentiful company, mostly with Muslims.