"an unprecedented and sophisticated attack on an electric grid substation with military-style weapons."

A bunch of yahoos with AKs light up a power substation and it's "sophisticated", as though literally any cowboy and his buddies couldn't have pulled this off drunk with no planning.

I'd bet against the feds doing it. They reputedly did attacks like this in Latin America during the various dirty wars, and taking out electrical grids is pretty standard during invasions, so I imagine the spooks have had practical experience doing it outside America. And they could just do a training exercise and have engineers work out what kind of damage rifles would do. My bet would be towards fashy survivalists and Amon Bundy types.