UFOs are real, just about 90% of all reported sightings aren't. The real sightings and incidents (military radar and visual contact sightings) prove that the capabilities of some of these are insane. The most recent in the US was the US Navy F-18 pilots off of San Diego USA in 2004, their aircraft carrier's radar picked up dozens of 10m wide objects dropping from an altitude of 80,000ft (24,000m) dropping down to the surface of the ocean, hovering in the water for several seconds then going back up to 80,000ft in a matter of seconds.
By the time the US Navy F-18s were scrambled from the carrier to intercept, only one UFO (in the literal sense, they did not know what it was) was left that was in their range to intercept which is when they caught it on video, traveling at 280kts (500 km/h, 320 mph), they caught several minutes of it before it went supersonic and dipped off their visual contact on the FLIR and ultimately off of their radar and the aircraft carrier's radar in seconds (the radar on the carrier has enough range to probe incoming missiles from space and still lost them in seconds).
In the government release, the pilot flying the lead plane said that the G-forces subjected to the UFO craft would not have been survivable for any living being on board at least to our understanding a human in an object that fast would die in several seconds. So they might not have even been piloted, they could have just been drones, as might be most real UFOs that are spotted in the world. So potential UFO technology would not even be useful to humans other than for learning of better energy and power sources, since they move too fast for humans to survive in them under normal physics.
Only 40 seconds released from the F-18s FLIR, the pilot interviews revealed more than the government did about the incident.
https://www.youtube.com/watch?v=3RlbqOl_4NA 
