There might also a lack of long-term strategy play into this.

I have two pet theories about how to handle small wars as the one in AFG:

(1) As described, build foreigners into the force till it turned foreign completely, shedding the too technicized TO&E components in the process.

(2) Send your troops, but set a withdrawal table from day one and tell the locals about it. Also tell them that for every WIA you take two replacements will arrive and for every KIA you take ten replacements will arrive - so violence against your personnel will have a perverted effect and be discouraged strongly. This approach is supposed to buy a calm period, for whatever purpose that's required.


Both could be combined, but (2) would lose effectiveness in such a combination.


Meanwhile, the standard Western approach under U.S. leadership is to send relatively few occupation troops, rotate them and reinforce them if politicians get too much under pressure by poor news about the occupation.
In parallel, indigenous puppet regime forces are being built from scratch, perform rather poorly and are unreliable for many reasons.