I have no personal experience with unidentified flying objects and don't have an opinion - one way or the other - as to whether or not they are visitations from the spirits. My now deceased husband had seen a UFO and was asked to appear on a television program with a panel. He was a pilot but the others there were not and were quite excitable and had all kinds of ideas of what the UFOs were, their "purpose" and such. My husband was not pleased to be in that company and ended his part in the panel by simply observing that what he saw was unidentifiable - if he could have identified it, it wasn't a UFO.
I do note that in Scripture, angels may appear as normal people ("Be not forgetful to entertain strangers: for thereby some have entertained angels unawares." - Hebrews 13:2") They may also appear with frightening demeanor (Daniel, etc.)
But even if the UFO's were some visible form of angelic visitation - I do not put any weight on a claim that they are among the Watchers. The angels in heaven do not have sexual relations (Matt 22:22-33) The Watchers (who according to Enoch were angels made in heaven but assigned to earth) were a uniquely assigned group of angels who had a physical manifestation such that they could and did have sex with women and produced giants (see also Genesis 6). For that conduct and more, they are all imprisoned for the final judgment. (Jude, 2 Peter 2, Enoch)
Without the evidence of such giants (Genesis 6, Enoch) walking the earth today, I do not accept the testimony of women claiming to have had sex with angels.
I understand. I think!
Thanks.