Unfortunately, a COIN doctrine published by the US military, whilst great, is no good unless its commanders have actually been taught exactly how to implement its doctrine.

There are many books similar to Nagls. I broadly agree with all of his assessments but remain sceptical that these lessons have been learnt, they have only been identified.

There are also wider issues. The evangelical christian movement within the US does not assist with the way in which its political objectives are pursued. A religiously motivated military, much like a politically motivated military is to be avoided. They should be apolitical through and through. Only then can the military commanders ensure that their objectives are realistic and that their political masters understand (as they frequently don't) what the military can and cannot be realistically be expected to achieve. Being 'yes' men is not good enough. Polticians need it spelt out to them.