Self quoting Fred Kaplan summarizing NYU Professor and Afghanistan expert Barnett Rubin:
Iraq’s insurgency is based in Iraq; Afghanistan’s Taliban insurgents are based mainly across the border in Pakistan. Iraq is urban, educated, and has great wealth, at least potentially, in its oil supplies; Afghanistan is rural, largely illiterate, and ranks as one of the world’s five poorest countries. Iraq has some history as a cohesive nation (albeit as the result of a minority ruling sect oppressing the majority); Afghanistan never has and, given its geography, perhaps never will.
Moreover, the Taliban’s insurgency is ideological, not ethno-sectarian (except incidentally). Therefore, while some warlords and tribes have allied themselves with the Taliban for opportunistic or nationalistic reasons, and therefore might be peeled away and co-opted, the conditions are not ripe for some sort of Taliban or Pashtun “Awakening.” Nor is there any place where walls might isolate the insurgents.