Lol
Not easy to get a weapon that is much more advanced than anything around kept a secret.
Like with the atom bomb.
Chinese are probably the hardest to spy on but there are usually ways.
And we can’t discount that it is some kind of weapon of ours
Or simply aliens watching us like and we watch animals in the wild
The “out there” hypothesis is not persuasive to me, and I have followed this stuff for decades.
Given the quantity of sightings of all kinds (and I think many are legit), I am convinced they have lived here and continue to live here.
Homo sapiens is very uncomfortable dealing with the possibility that we are not the top of the food chain.
Or simply aliens watching us like and we watch animals in the wild
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We may be vaguely interesting to some alien anthropological study group. The ones unlucky enough to pull an assignment in this galactic backwater.
“Earth? Earth! You’re seeing me to Earth! How come Joe keeps getting all the choice assignments?”
Highly unlikely another country has something so far advanced and sends it to play around our bases, we see them but have no idea where they’re from.
Seems unlikely it’s ours and gets chased by our own planes
Then again a somewhat nutty friend says an ex CIA guy told him they definitely are ours.