The leaks to the state controlled media (New York Times etc) strongly imply they are probably NOT aliens. Same with “experts.” For some reason, they are pushing this line.
The most logical explanation, if our military pilots are to be believed, that they can do things no power can do, then it is likely they are not of any known Earthly origin.
Not true.
Both the NY Times and WaPo have said "they are not the U.S., China, or Russia.
And though there is no "evidence" in hand as yet, the alien hypothesis cannot be eliminated.