I thought everyone knew what the real story was. After the Soviet Union fell, some of their KGB documents and defectors showed they used UFO reports in the United States and several other nations to spread distrust of their governments. But wait, as they say on TV, there's more.
Later FOA requests some few years ago from the CIA and other agencies described how, after the defeat in WW2, the US gained several rocket scientists/engineers, including, famously, Dr. Werner Von Braun. Also imported were several experiment aircraft seized at Pannemunde (not sure of the spelling), including at least one prototype with a circular (saucer-like) wing arrangement. As I am quite an ancient dude (ignore the handle) I remember seeing grainy photos of some of these aircraft, possibly taken by servicemen, which were published in either or both Popular Science or Popular Mechanics magazines. I was just a small kid at the time, so it was probably ca. 1947. These planes, according to the CIA response to the info request, were taken to a testing airbase in the New Mexico desert (think area-51) where they were studied and test-flown, and found to be quite unstable as they were involved in frequent collisions with the ground, causing numerous pilots' deaths. Contemporary reports of these crashes by civilians spread throughout the US, while its government denied the existence of these crashes and the erratic, saucer-shaped craft. It was the Cold War, and the USSR used their network to spread other fictitious reports (see above paragraph. Rinse and repeat.)
The CIA saw what they were doing and did it back to them, spreading false reports throughout northern Asia and then to the more populous western regions. Suddenly, UFOs were a worldwide phenomenon!
As Paul Harvey https://en.wikipedia.org/wiki/... used to say, "And that's the rest of the story."