Epistemic status: Big if true/I am clearly an idiot for even posting this.
Some apparently real journalists have been approached by (& approached) several intelligence officials, some tasked specifically with investigating UFOs, who claim that the DoD has had evidence of alien intervention for a while in the form of partial & mostly-whole fragments of alien aircraft. A followup article where the publication outlines how the editors verified this persons' and others' claims and affiliations is here, and a part 2 is expected tomorrow.
For some reason - very possibly because it's complete nonsense, or because they haven't had time to independently verify - the story has only been picked up by NYMag so far. The consensus among the people I've been reviewing this article with, is that it's either a complete hoax (i.e., the entire thing nearly top to bottom is some deliberate deception) or there's a non-negligible (>5%) chance aliens are here. I would love for someone who has a good understanding of the material to give an explanation (including possibly on priors, just thinking clearly about the content of the article) of why my friend group should discount this out of hand.
Thus far I have been unconvinced by most stories of why we should to-the-point-of-not-caring-about-UFO-sightings-expect Aliens have to be big and obvious and tile the universe with fun, as opposed to operating some sort of noninterventionist monitored lightcone.
Reusing a response I made to a previous UFO story, on a mailing list, lightly edited because the same logic still applies.
There's one core truth that you need to understand, and then all the talk of UFOs, videos, and the reactions to them make sense.
The US military has secret aircraft. Other militaries also have secret aircraft. These are kept in reserve for high-stakes operations. For example, in 2011, a previously-unseen model of stealth helicopter crashed in the middle of the raid on Osama bin Laden's compound. Rumor is that the Chinese military got to inspect the wreckage; if true, this would be a pretty major fuckup, since it would enable them to plan around its capabilities, to design radars to detect it, and to attribute any operations using it to the United States.
The performance characteristics of secret military aircraft are military secrets. They are highly prototypical military secrets. That means the secrecy radiates a few conceptual steps outward: our own country's aircraft are secret, what we know about other countries' aircraft is secret, what we know that other countries know about our aircraft is secret, and so on. Deliberate disinformation is expected; if you look far back enough in time for things to be declassified, you'll find publicly-reported examples of the US putting out fake aircraft mockups for Soviet satellites to photograph, and similar tricks. There are a few videos taken from fighter-jet sensor packages floating around; these require some expertise to interpret, or else you'll wind up thinking that the sharpen filter is a glowing aura, or that the parallax is a fast movement speed, or that image-stabilization problems are fast accelerations. As it happens, the characteristics of fighter-jet sensor packages are *also* military secrets (perhaps a bit less well kept), which means that 100% of the people who are qualified to interpret those videos, are also legally forbidden from talking publicly about them.
With that as background, there's nothing left to explain. Given a specific video, it can be hard to tell whether it's an aircraft with a surprising capability, or a fake video, or a sensor issue. That's the point; foreign military strategists will also look at those videos, and encounter the same problems. Dispelling the confusion would mean accepting a substantial handicap in future military operations, and there's no reason to do that.
That seems to be a public justification for why the AATIP was started in 2007. It's worth noting that the US air force didn't want AATIP. Harry Reid forced them to do it because Robert Bigelow encouraged him to do so.
AATIP seems to come up with the term UAP to remove the stigma associated with the term UFO. That does not explain why AATIP reported having found the strange incidents that it found.
It certainly does not explain the reporting of a 90-year coverup of programs to retrieve UFOs. That's not the kind of news you would want to produce if you want to reduce stigma.