I'd rule out E.T. They wouldn't give a damn (let alone even know about) green and red lights.
I'd rule out foreign adversaries. Chinese balloons were one thing. Drones we can easily track on radar, knowing direction, altitude, speed, etc.
That leaves nothing else left but us. The question is why? And that's the concern. Does it have something to do with what we suspect Russia in planning (in Europe) or China (in the Pacific)?
Or are we testing new technology? But why over populated areas where our foreign adversaries can learn from our tests? I don't think Trump will give us a answer (or at least not a truthful one) in January, either. I suspect he's already been read into what the real answer is.
