I'm skeptical of the idea of the idea of bases with fallen angels underground. I think the government is genuinely stumped, and still mostly toying with the extraterrestrial hypothesis. Many people are. Even though there's plenty of folkloric evidence that "UFO's" and "aliens" are a quite old phenomenon that predates modern space flight, going back thousands of years, and may be part of a conscious control system, similar to the "principalities and powers" mentioned in some of the Pauline epistles. They communicate through symbols, offer their own kinds of "communion", usually in the forms of symbolic, often intrusive, initiation rituals, sometimes sexual and coercive in nature. Playing around with them risks intellectual and spiritual seduction, and in some cases insanity, illness, or death. And there's a long record of their fear of Christian religious symbols and prayer.
The fact the US ranks highest in UFO sightings in the world per capita may be a sign that the US basically lays out a metaphysical welcome mat to everything of the occult, and might also represent a kind of divine judgment, perhaps the gates of the Abyss have been opened upon the United States? The rampant narcissism and unmoored spiritual yearning is an invitation to these beings, who often will attempt to play up the "choseness" of their victims, enticing them with intellectual and metaphysical seductions that appear deep but often amount to nonsensical riddles and seeming profundities devoid of context, or outright lies (like claiming to be from Mars, Venus, or Zeta Reticuli, even though we know for a fact none of those places can support intelligent life).