Whilst the this thread's topic is "green on blue" as one observer remarked I do wonder how many ANSF on ANSF deaths or violent incidents there have been?
Given the multi-ethnic composition of the ANSF, surely some of the causation we have all remarked upon applies within too.

I have checked two of my books on the Imperial era on the North-West Frontier, for the experience of the British officered 'Scouts' and found a 1985 review by the late General William Jackson of 'The Frontier Scouts' (my standard text on the Scouts).

Mutual respect and trust...They were all poachers turned gamekeepers: Pathans recruited to keep the peace amongst Pathans....the Pathan's loyalty transcended his tribal affiliations. But loyalty between different races and creeds rests upon the knife edge of suspicion... (there were) so few defections and mutinies occurred in the ruthless atmosphere of the frontier.