Unidentified Aerial Vehicle (UAV)
On mid-afternoon, November 14th, 2004, off of the coast of San Diego, Commander Fravor and the other pilots in his squadron were diverted from a training mission to investigate a U.S. Navy cruiser’s report of strange craft that would drop suddenly from 80,000 feet to hovering at 20,000 feet or disappearing off radar. 
For two weeks, the Princeton had been tracking mysterious aircraft. Fravor described a 40-foot-long oval object with no wings or plume from any engine—a “flying Tic Tac”—conducting erratic flight maneuvers. Fravor cut his F-18 across to approach the unidentified aerial vehicle (UAV) , getting to within a mile. Once in sight and in line of intercept, however, it would either mirror Fravor's motions or conduct evasive maneuvers to stay several steps ahead of his next move.  Fravor conducted an interview with ABC News:
I can tell you, I think it was not from this world. I've seen pretty much about everything that I can see in that realm, and this was nothing close. I have never seen anything in my life, in my history of flying that has the performance, the acceleration—keep in mind this thing had no wings.
You know, you see a lot of interesting things. But to come up on something that's a 40-foot-long white Tic-Tac with no wings that can move, really, in any random direction that it wants and go from hovering over the ocean to mirroring us to accelerating to the point where it just disappears—like, poof, then it was gone. "