Simply cut the power in that grid and make them pay to turn it back on. Cut the Cell Towers and tax Verizon, AT&T, etc. foreign rates. Tariff any goods that come and go from there. After-all they put up the sign saying they aren't a part of the US.
This is appears to be the most benign hostile occupation by terrorists I’ve ever heard of.
I still get a good chuckle from people who don’t have a college education ridiculing those with college educations. Classic.