The CIA invented the modern conception of the alien whole cloth in order to carry out psychological studies on the public and to provide some cover for military actions. They used a combination of mass manipulation, the media, dupes, knowing individuals, and drugs to do it all. They tortured people to convince others that abductions happened. They purposefully sowed confusion and arguments about the nature of our universe. Historical accounts that misinterpret astronomical phenomena are then purposefully and accidentally misinterpreted as accounts of alien visitors. In other words, if those people had never heard of aliens, never seen an alien movie, etc they would interpret manuscripts, tapestries, wood carvings, and paintings as something else. But because those things are so pervasive in modern culture, they’re interpreting those things as aliens. It’s like how nobody before the advent of the helicopter confused hieroglyphics in Egypt of portraying helicopters. But after the Apache was invented you suddenly get ancient alien doofuses thinking certain damaged hieroglyphs are depictions of helicopters. This is part of how the CIA can brainwash tons of people. If you put that shit in the media hard enough, people will start to see it everywhere. They will make it real. And the CIA spent pretty much all of the Cold War fucking with the public. This is what would eventually transform into methods used to initiate the existential threat of terrorism too.