9,800 is enough for a small reaction force, a moderate number of trainers, liaison, civil affairs, intel, special operators, and logistic support including airfield ops people. Spread around a place the size of Afghanistan, it's about the size of the force you'd leave if the situation was pretty stable and you just wanted to keep a lid on the scattered die-hard hold-outs in the mountains.
Unfortunately, the situation is not stabilized, and there are a whole lot of heavily-armed, ruthless, fanatical SOBs in the mountains, not just some isolated hold-outs.