John E. Greenewald, Jr is an author and podcaster who runs the Black Vault, an online archive with 2.2 million pages of government documents, mostly dealing with UFOs and the paranormal. Basically, he's FOIA X-Files. And he recently published a huge trove of CIA files on Unidentified Aerial Phenomena. He explains:
The Black Vault's connection to the CIA in getting some of these UFO documents released goes back to 1996.
Originally, the CIA would only release about 1,000 pages that had been previously disclosed after a FOIA court case in the 1980s. They never addressed the records that were dated in the years after the case.
The Black Vault spent years fighting for them, and many were released in the late 1990s. However, over time, the CIA made a CD-ROM collection of UFO documents, which encompassed the original records, along with the ones that took years to fight for.
In an effort to make sure The Black Vault stayed up to date, in mid 2020, this CD-ROM was purchased to have one particular data dump available for all users of The Black Vault. You will find this below for download in its original state, along with a converted/searchable .pdf format. (Although the CIA claims this is their "entire" collection, there may be no way to entirely verify that. Research by The Black Vault will continue to see if there are additional documents still uncovered within the CIA's holdings.)
There are notes on Bosnian fugitives arguing with extraterrestrial contacts, your token unexplained explosions in small Russian towns and Soviet Ukraine, a 1976 record of UFOs in Morocco, and so much more to sort through. There are also entirely separate but supplemental Black Vault archives of official FBI files on paranormal activity and the CIA's Remote Viewing program.
Also worth noting that the CIA apparently sends these documents to Greenewald as cumbersome multi-page .TIF files, which he has to manually convert into searchable PDFs. Woof.
If you're not able to comb over all these documents by yourself in the next six months, don't worry—the COVID relief bill included a passage requiring the Pentagon to release some more documents by June 2021.
UFOs: The Central Intelligence Agency (CIA) Collection [John E Greenewald, Jr. / The Black Vault]