[Pre-Sept 11, Al Queda was brought in as the military arm of the Taliban. Why is there still a Taliban???!]
As the president said, we could wipe out the Taliban very quickly. But that would entail exterminating their civilian supporters. Alexander killed the entire male population of Persepolis, the capital of Persia, and sold the women and children into slavery. No enemy civilians, no insurgency. The Afghan analog would be Pashtuns. I expect if we killed every male Pashtun, the Taliban would die with them. But there is zero possibility of us going that far.
https://www.livius.org/sources/content/diodorus/alexander-sacks-persepolis/