UFOs are classified as those from outer space or made by the extraterrestrials. But there’s a fact based on evidences that there are UFOs that are terrestrials in origin – made by man.
The video here is a documentary proving that superpowers during the earlier times of aviation research have invented flying saucers but were highly classified and used only for special missions.
Today, the flying saucer technology is used for the making of drones though there are speculations that militaries are using real flying discs in covert operations.