As noted in the recent Pentagon report, the first four categories don't seem to explain what is being seen. Those categories being 1) Airborne materials like trash, balloons, birds, etc. 2) Atmospheric phenomena; 3) US or private industry developmental craft; 4) Russia, China or other adversaries. Ruling out those categories leaves " OTHER " which is unspecified as to being alien, ET or anything else.

These incidents seem to be increasing in frequency, and many of them seem to involve surveillance of Earth's military assets. Violent confrontations usually result in military losses.

What else do you want to know?