Pak army is fighting only a segment of pakhtun society i.e talibans yet they are dying in thousands in FATA....the whole Afghanistan is like FATA, it can not be conquered, it is graveyard of empires, you can not occupy it for long..those pakistanis who talks of conquering afghanistan are PC warriors, nerds wearing glasses and good only at typing fast.
Dude no one in their right senses want to occupy or conquer Afghanistan. There was never any talk of unification even when Taliban were in control. Its tit for tat among many Pakistanis and Afghanis both boosting senselessly.