1. The whole thing is a dis-info campaign to hook a near adversary into thinking we have spooky next gen technology. This all being public makes me lean this way. Similarly perhaps this is being used as a cover story for some impressive but not physics defying drones, similarly to how "UFOs" were used as an diversion away from projects like Mogul or the f-117 and B-2.
2. Pais is a conman, scamming the military into funding his fraudulent tech.
3. Pais is a breakthrough genius. The Tech is real and in years it will be revealed to the public.
4. The "Bob Lazar" option. "UFOs" as in foreign objects exist and occasionally crash, and are studied and reverse engineered when they do.
It's interesting to note that Pais was recently transferred to submarine command.