Your right if we use current US military doctrine. I am certain that the Mongols, if brought to our time, would be able to pacify Afghanistan in under a year with ruthless, lethal, efficiency. Every village that resisted would be put to the sword, most males would be enslaved and castrated, the women would be either married to or concubines of the Mongols and in 10 years the populace would be genetically half Mongol.
We need to fight them in the winter which is when fighting usually quiets down as travel in the mountains becomes extremely difficult. That is when villages that are Taliban strongholds are very vulnerable. the US should form packs of attack and troop helicopters and focus on one mountain valley at a time. At nightfall helicopters would transport small combat units to blockade strategic trails and passes to seal all escape routes with snipers.
Once that was done the starting at the lower elevation, open end of the valley invade several villages at a time and kill every taliban that can be found. Every man in the village should be identified, photographed and issued a picture ID that they must have on them at all times or face execution. The leaders of the village, the Khan, the elder, and the Mulla should be taken as prisoners and removed for several weeks for intense but mostly human interrogation and reeducation. Then onto the next village up the valley.
Any leader found to be a militant should never be allowed to return anywhere near their home village for at least 5 years. When freed these militants should never be able to associate with one another. If a leader of the village is found back in hi home territory he should be executed on the spot along with the leaders of the village.
Why?
Why would we want to expend that much time and effort?