Most would be led to think every U.F.O. that's witnessed is the product of a distant alien. I believed this for a while until I started looking into the proof that humans have been creating flying saucers since world war one. In recent times, dating back to the 1940s and 1950s, humans have patented "vertical take-off and landing"(VTOL) aircraft. These are circular-winged aircraft built to move with reflex in any direction: up, down, forward, backward, left, right and diagonal in any direction - more like being able to shift to any point within a bubble rather than a winged plane's very limited forward and side motions.
You will find various propulsion systems in these documents - everything
from accelerated particles to the awful rocket. The ethical concern here is the mainstream's approach to the "UFO". In their opinion, every UFO is either the misconcetion of a strange person or it is displayed as being the product of another world. I do not discredit the existence of "the fallen", but I do not believe they come here in mechanical flying discs. These are the product of humans and have been since before the first half of the 1900s. Link to Human-Made Flying Saucers Document collection: http://human-made-flying-saucers.webnode.com/