Bolding the part that's a given - and not necessarily only by the global powers. How many times have you heard proponents of Balkanisation even on here?
Stand by my figures though - because the rural parts simply don't matter at first. If I were doing it and could expect only sporadic resistance from the military, I'd put troops in the major nodes - NYC, LA, Atlanta, Chicago, DC, Houston, Miami - probably Portland too and KC. Come down incredibly hard locally - yes people would escape, but to where? They'd do the pre-pacification of the hinterlands for me - look at Syria for a fine example of that. I'd be encouraging the exodus!
First problem is that the hinterlands aren't so much anymore. You'd have to cover many more cities. Even places now like Omaha, Des Moines, Milwaukee, Huntsville, Oklahoma City, or Cleveland have half a million to a million people in their metro. There are 106 metros in the US with more than half a million population. If you don't have a significant troop presence spread around, you will encourage secession, especially in the interior. Americans have a tendency to think local and making examples of far away cities may not have the desired effect. Alot of that will hinge on the leadership of our Governors.
Which brings us back to the paradox. Assuming even that they could keep the gangs under control, the cities are still going to burn. Which will crash the economy, tax revenues dry up, welfare and unemployment claims spike, and we won't be buying foreign goods to recycle back to bond purchases. Then interest rates will spike, and the economy will simply implodes. Our currency will be worthless so fast it'll make people's heads spin. People just don't understand how precarious our financial situation truly is.
None of which factors in that even though it'd be a stupid move, they still may try it. I just think it'll not go down as they think it will, and will mostly backfire. They always have that longshot to pull it off and everyone be compliant, but in the end I think they'll just run out of money.