<<Too obvious and might seem a bit, well, unseemly. Better to wait a few months and then ZAP him when he's on the lamb.>>
When nobody knows whose predator drone got him? Nothing unseemly 'bout that.
Fact is, it doesn't matter what you do to them. They were resolved to die the moment they joined the struggle, and there will be dozens, if not hundreds more to replace them.
I'm like Lincoln - - I believe you destroy your enemies by making them your friends. These guys have major beefs against the U.S.A. and you should listen to them. Otherwise, they'll always be able to inflict little mosquito bites on you (like the WTC/Pentagon attacks) and you'lll bust your balls trying to get them, in the process alienating most of the world, solidifying their movement with every "success" you have against it and in the end falling back to third-ranking or tenth-ranking position in the world while your rivals, China, the EU, India and maybe Russia and Brazil, soar past you, unburdened by the ever-escalating costs of fighting a self-renewing hatred engendered by their own actions.