Alexandria
We should do what the Great One did. Find the friendliest, most moderate ethnic group in Afghanistan, and build them up. Take all of the billions we're spending in Afghanistan and put it into one region. Create an ultra modern city for the capital of the region, and populate it with moderates and/or secularists. By creating an Israel or Kurdistan in the Northern area of the country, we could use them as our proxy to strike throughout the region as needed.
The Pashtuns are too primitive and radicalized to continue messing with. Poison their wells and blight their land with biological agents, then quarantine the region of southern Afghanistan and the tribal regions of Pakistan. Let them rot in their little corner of Hell.