You don't seem to know too much about (1) what tac nukes actually do nor (2) what the terrain is like in central Afghanistan. If you put a tac nuke 5 miles from a target on an open plain it wouldn't do anything to that target - that is one. If you draw a circle with a radius of 5 miles in central Afghanistan around a random point on the ground, there will be peaks 5000 feet above the level of your point between you and the target i.e. -cubic miles- of solid rock. Oh, and the Afghans have only been tunneling safe locations out of the rock for about 22 years, to avoid air surveillence and attack.
Elaborate firepower is not what the terrain is suited for. It rewards skilled infantry warfare, especially by stealth. You are more likely to get a particular man by stalking him for a month with half a dozen four man teams with sniper rifles and advanced vision gear, than with all the air power you'd care to waste.