Alien conspirarcy theories worked as a baseline test for the CIA to track how effective propoganda and misinformation is before they rolled out the same techniques in places that it mattered for US foriegn policy interests.
https://sgp.fas.org/library/ciaufo.html
https://lareviewofbooks.org/article/the-truth-was-out-there-on-the-legacy-of-art-bell
https://www.nytimes.com/1997/08/03/us/cia-admits-government-lied-about-ufo-sightings.html
I should say, this is mostly speculation based on reading a lot of COINTELPRO and MKULTRA stuff, it seems likely a way to test obsfoucating military technology through misinformation.
Furthermore if you notice the global UFO reported sightings, it seems to only line up with where American media has a hegemony, which is strange considering China has nearly 2 billion people in it, you’d think one of them might have seen one; it seems to only be where american media has reach that ‘UFOs’ start to appear and I dont think thats an accident.
