To what end?
The purpose of United States psychological operations is to induce or reinforce behavior perceived to be favorable to U.S. objectives.
1. https://en.wikipedia.org/wiki/Psychological_operations_(Unit...
To spook enemies of the US and create a mystical aura of superiority around the US military and its capabilities. They're literally creating the impression that the US military has technology beyond the "Clarke threshold." (The Clarke threshold refers to Arthur C. Clarke's maxim that "any sufficiently advanced technology is indistinguishable from magic.")
To shake out moles, spies, and unreliable people / leakers.
As a cover for very terrestrial extremely advanced technology such as hypersonic weapons, drones, laser and directed energy weapons, etc.
To repeatedly float the idea of "alien disclosure" and then dash everyone's hopes in order to discredit the idea of extraterrestrial life and visitation. Why? Maybe they're concerned that we will eventually detect aliens and they want to blunt the cultural impact by making the public skeptical. Maybe they actually do have evidence of aliens (but maybe less sexy than crashed UFO parts) and want to keep it quiet, so they want the topic to be discredited and marginalized. Maybe there's some ideology at play like religious fundamentalism. Why knows.
A lot of them are still fighting the Soviets
I have zero confidence that any government or their populace will be able to handle that realization without going completely bonkers. We simply can't handle it as a civilization. For every sane person who is curious and wants to interact positively with the artifact/being there will be a dozen different types of maniacs out to destroy whatever it is.
And if you believe that governments reflect the neurosis of their people, it fundamentally impossible for any government to deal with something like this rationally.
US adversaries can easily turn their drones into a panic when they fly in US airspace, and I believe that the instances where actual drones are involved, those are attempts at adversaries to surveil our military and government and to scare the populace. That's to say adversarial drones have an additional use as psyops weapons against civilians and military members. Being able to send whatever you want into US airspace and the US being unable to do anything about it can be perceived as being threatening and scary.
A counter narrative to that involving some UFO/alien mystery can quell panic and instead foster wonder and distraction.
When I hear about this alien stuff or other "big government" conspiracies I'm always reminded of this saying, not sure where it's from.
"Behind every vast conspiracy theory is a sincere hope that somewhere out there, someone knows what they're doing."
(i.e., conspiracy nuts in a sense really want to believe in an all-powerful government because it would give them an assurance that someone really does know what's going on).
Modern civilian OSINT would have been adequate to deduce fission work was being performed, assuming no one posted centrifuge schematics on their gaming Discord.
And it still didn't succeed, the first world leader to learn that fission weapons work was Stalin.
"... the conspiracy theory Project Blue Beam, which concerns an alleged plot to facilitate a totalitarian world government by destroying traditional religions and replacing them with a new-age belief system using NASA technology."