Sure, they have "highly advanced prototypes" where those prototypes obey the known laws of physics and experience inertia.

They have drones that are better than the existing drones. They absolutely don't have drones that are anything like the impossible vehicles in these UFO reports though.

If some radio and optical trickery may lead an observer to believe that the device moves in impossible ways, it's valuable.

Remember that we have strategic bombers with a radio signature of a trash can, or whatever. This is seen as normal, and has been publicized for decades. Same with Russian supersonic fighter jets that can stop in the air for a moment.

If we (or "they") have a drone with a visual signature of an inertia-less device (under certain angles, doing a special manoeuvre, etc), this does not mean they are actually inerta-less, but that they can fool the aiming systems.

> If some radio and optical trickery may lead an observer to believe that the device moves in impossible ways, it's valuable.

Pretty sure this was ruled out by the multiple methods of observation used.

I don't think so. It's at least conceivable that an induced plasma phenomenon could be visible to radar, IR and the human eye.

>it does also seem possible the USAF could have highly advanced prototypes that aren't ready for mass production yet.

And have had them for decades now, if UFO reports are to be believed?

UFO sightings aren't new. The capabilities people report don't seem to be getting better over time. If UFO reports are (sometimes) real and they're advanced US prototypes not ready for production, what were they 30 or 40 years ago? Have UFO reports only been real for the last 10 or so years?

My bet is that none of them are real. Of the ones I've seen, each one is different, each one had zero measurable impact other than some people and some cameras seeing something, and each one has its own perfectly reasonable explanation, usually involving photo editing, lies of a witness, and natural phenomena like e.g. internal reflection in the camera housing structure that changes as the camera rotates trying to track it.