The existence of aliens has been wildly debated, although you'd be a fool to think that there isn't life outside of the planet earth. While there hasn't necessarily been concrete evidence proving that aliens exist, it appears as though the Department of Defense has some documents and footage related to UFO spottings.
In response to a public records request filed by Vice, the Navy has revealed that there have been briefings about UFO spottings including one between the USS Nimitz and an unidentified flying object. The Navy responded to the FOI request, writing they 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 Original Classification Authority has determined that release of these materials would cause exceptionally grave damage to the National Security of the United States." Adding, "We have also determined that ONI possesses a video classified SECRET that ONI is not the Original Classification Authority for.”
Despite admitting to the existence of the footage, a rep for the Pentagon said that there are no plans to release it. "However, I can tell you that the date of the 2004 USS Nimitz video is Nov. 14, 2004,” the spokesperson told Vice. “I can also tell you that the length of the video that’s been circulating since 2007 is the same as the length of the source video. We do not expect to release this video.”