on this one.

from wm
Two points:

(1) The final question above ["Do we have the forces available to do it?"] indicates the wrong mindset. I not so humbly submit that prevention (action during BW's Phase 0) is not a military option; it does not require "forces." One's military may be used for things like civil works projects (the kind of stuff the Corps of Engineers does for example) but not for doing warfighting or policing type activities.

(2) Prevention outside of one's own sovereign land is not possible. Trying to stop an insurgency elsewhere is an example of the "leading a horse to water" problem. As noted by others in this thread, the host nation has to see that the nascent problem exists and desire to do something about it. The only thing outsiders can really do is to keep identifying that, as Marcellus said in Hamlet (Act I, Sc 4), "Something is rotten in the state of Denmark."
So, we are solidly based (IMO) on political action as the key to Phase 0 problems.

To paraphrase Ross Perot, the devil is in the details. The first problem is the outside nation's sense of smell. If that sense is impaired (as badly as my own is in reality), it will smell nothing or get the wrong scent. The same thing applies to the HN. Given all the variations in cultures and politics, outsider and indigenous recognition of the existence of the problem, the nature of the problem and the solution(s) to the problem, are more likely than not to be on different pages.

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While wm calls this an "aside", it opened up a window and provided some daylight in my swamp,

An aside:
I just started reading The Wars of German Unification (Modern Wars), by Dennis Showalter, published in 2004. In the first chapter, he discusses the period around 1848, describing, among other things, the work done by the armies of Prussia, Austria and the various Germanic principalities in counter-insurgency (he actually uses that term). He notes how poorly they did at it and how blind the various Germanic states were to the causes of the insurrections. He also briefly discusses the debate in Prussian military circles about the value for officers of an academic preparation/study in the art of war.
because it gave me a jump start to my problem of "I guess I need some more cases of Phase 0 - successes or failures - to grasp the parameters we face."

My thought is that we can take any rebellion, revolution, etc., and find a Phase 0 - which in those cases was obviously not handled well because an armed conflict of some kind resulted. We can then beat the horse to death finding the causes and the solutions - and all of that will be in hindsight and shaped by our present sense and mindset. From that, perhaps, we can glean some general principles and some future guidence - maybe.

What we want to head off in a Phase 0 situation is a Detroit Riot: Something north of 600 buildings torched directly or indirectly (DFD had to withdraw from the scene in many blocks); besides local LE, some 400 MSP troopers deployed (insufficient and beyond their operational scope); some 9200 NG troops (who were then at "summer camp" in The Mitten, 200 miles away - their Detroit deployment a total cluster flop) and 2700 regulars (Airborne), whose quadrant was the only TAOR with any sanity. A "police action" ?

Could reasonable steps have been taken before the "blind pig" raid to avoid what happened (other than the obvious - don't raid the bloody place). Maybe, but whoever wants to tackle that will have to have more time on his hands than I have.

And, in searching any given revolution for its Phase 0, how far do we want to go back to find that Phase 0 ?

I can make a case that Phase 0 before the French Revolution was broken some 180 years before heads were cut off - this incident from 1610 as an example - a map here.

L’échauffourée légendaire du pont Monseigneur en 1610, au cours de laquelle François de Vigny fut mortellement blessé par ses paysans ...
The bottom line is that François de Vigny was un plus grand SOB, who abused his peasants, called in the army (probably the gendarmerie) to quell them, and got whacked in the process - which then meant more troops had to be called in, who settled all armed conflict issues in the effective manner of those times. 179 years later, the situation existed on a larger scale and most troops refused to fire.

So, how far do you want to go back to find causes and to develop hindsight solutions ?