The Navy is very clear: They don't know what it is. The audio of the pilots is also clear - they saw it with the Mk0 Eyeball, the camera also saw it,, and the radar got a weak hit... so the camera was able to track it.
It's far more scary that they don't know than if they were certain it was an alien. If we knew it were aliens, it would be a comfort, but also change entirely the DoD response.
It's interesting that the debunkers I've seen are flatly ignoring that one of the released vids is aircraft-cam footage, but with radio & intercom voice over it. The vid has the pilot confirming that what's on the screen is also seen by eye out the window, and with a wingman, who also confirms video and visual contact. 4 people, 2 planes, 2 very different systems (eye vs camera) with different refractive indices and fstop/lens configurations... and the debunkers, all 3, claiming it's purely camera artifacts. The debunkers debunk themselves...
But that vid, despite confirming visual recording in IR, and noting visual sighting of the recorded object by 4 people, is evidence there are transsonic objects being observed in flight... but nowhere near to being evidence of aliens.
What could it be?
- Per DoD spokespeople, potentially a european nation¹ with an unannounced advanced drive.
- It could be aliens.
- It could be terran non-human intelligence which fled earth and returned
- It could be some loon with a gift for engineering who made a super drive and is hiding from the gov't to avoid it becoming a tool of war
- It could be a sensor of a Von Neumann machine - be it of the Earth or not.
- It could be mass hallucination caused by camera error... but that's not really that likely, since the USN has hundreds of similar sightings. The mass is just too many bodies to have a significant chance of being the correct solution...
- It could be a time travel experiment. (Possibly from the other end. Thanks, Michael Crichton...)
- It could be a huge disinformation campaign...
- If it is, sooner or later it will turn up in federal records
- if it is, sooner or later one of the principals will recant.
Occam's razor only gets us to "it's probably a real phenomenon"... because the conspiracy and mass hallucination triggered by malfunctioning gear are a bit too far out.
... and if real, we don't have enough to know which nations are in possession, nor if those nations are modern and terrestrial Terran.
Perhaps there are some tool using tentacular Terran intelligences hiding deep under the water... think something between octopus and sliug... with human level intelligence and coöperation... I doubt that idea, but man it would make a fun episode of some conspiracy shows.
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¹ Remember: Russia is also European. Technically, so is Turkey. Even as both also count as Asian nations...