The U.S. Navy acknowledged the existence of the information, which concerns a 2004 encounter between the USS Nimitz and strange unknown aerial objects, in response to a public records request from Vice.

Last year, the Navy for the first time acknowledged that three UFO videos -- one from the 2004 USS Nimitz incident and two from 2015 -- were real videos of unidentified flying objects.

Responding to Vice's Freedom of Information Act request, the Navy said it had "discovered certain briefing slides that are classified TOP SECRET. A review of these materials indicates that are currently and appropriate Marked and Classified TOP SECRET under Executive Order 13526 and the Originial Classification Authority has determined that release of these materials would cause exceptionally grave damage to the National Security of the United States."