https://www.vice.com/en_us/article/jgmnqd/obamas-presidential-library-has-thousands-of-files-on-ufos

The Barack Obama Presidential Library claims it has “3,440 pages and 26,271 electronic files” possibly related to the existence of UFOs and related phenomenon.  

We know this thanks to a Freedom of Information Act request filed by John Greenwald Jr. of The Black Vault, a clearinghouse of declassified government documents. Greenwald Jr. asked the Presidential Library for “documents and communications about the Advanced Aerospace Threat Identification Program and photos and videos of Unidentified Flying Objects, Unidentified Aerial Phenomena/Phenomenon and the Advanced Aerospace Weapons Systems Application Program.”