Japan:
In reply to USA (msg # 21):
...or the reason for the rebellion is improved/removed, ie conditions improve, certain rights are extended to the population.
That's a "special case" of getting them to lose interest in insurgency. I suppose I phrased it badly when I said "getting them to lose heart" - but of course at extremes this blends into "insurgency ends because it wins" (succeeds in achieving enough of their goals/objectives that the insurgents see it as fullfilling their victory conditions).
Russia:
But this could serve equally well in an insurgency, where so many of the rebel units have Stealth (sec 12.11), they can avoid combat long enough to be repaired (sec 12.7), so the core of the rebellion can survive to return again and again until finally rooted out
While that works in a sense I'm still not sure it replicates the "strength" of an insurgency; insurgent economies tend to be "weak" by official stats, but they can keep fielding units rather repetitiously. Not, say, once every five years or even once every year or so.
What makes insurgencies bothersome, at least to powers as represented in this game, isn't their threat to win battlefield victories against a great power (typically), they'll get repeatedly defeated. But they just don't go away and they raise a disproportionate cost threshold on their opponents. Basically in "game theoretical" terms, insurgents try to affect the cost/benefit ratio to the point where intervening powers question whether it's worth continuing to stomp the anthill month after month year after year. (Contrarywise, the government/intervening allies attempt to affect changes as mentioned above, aimed at making the insurgency go away. And, yes, "carrots" can be part of changing the perceived cost/benefit ratio in the minds of the "base population" of insurgencies).
It's probably going to be kludgy to try and satisfactorilly model insurgencies in the game system, since overall it's intended for interstate war rather than intrastate conflicts. But I decided to babble anyhow.