The Pentagon checked and determined - have aliens visited the Earth and what are all the UFO sightings? - Voila! Technology. The report details new technologies tested over the years including high-altitude balloons - which have inspired waves of UFO speculation.
The increase in UFO sightings in the 1950s and 1960s was likely caused by testing of advanced American spy planes and space technology. Officials also said there is "no evidence" that the US government itself has encountered aliens or is hiding them.