In my opinion (my thread on this was deleted) this is a Psy-Op by the FAA/AF & corporations that is not coincidentally occurring at same time as the Draconian FAA NPRM to destroy the recreational drone community. The 'mystery' drones are reportedly up to 6 ft in span(not recreational), operate at night (needing FAA waiver), hover with spot lights on for up to 10 minutes at a time(big batteries), fly in coordinated grid patterns(programmed routes), make lots of noise. You can't tell me that the FAA can't figure out what large fleet of registered drones are operating under a night time waiver. You can't tell me that the drones can't be tracked, that is ridiculous. Put some good storm chasers on them and if you have several fanning out in several directions it should be a simple investigative task. The FEDS are just trying to terrorize certain people into reacting with cries for more drone regulation to stop these 'alien' privacy-breaking spies in the sky in my opinion. I thought that the big drones all had some kind of id that could be tracked much like the manned airplanes have called ADSB.
If you ask me, some corporate operator is flying the drones, the Air Force is allowing the rumors of their involvement as some 'secret' testing for terrorist attacks as a cover story and the FAA is happy to use the 'mystery' for their purposes to destroy the recreational drone community. They don't like the competition that this would give to the commercial drone operators. It is all about making the sky's 'safe' for the coming commercial drone fleets. This is just a Psy-Op if you ask me.