I think we have but kind of odd the navy wouldn't know about it unless it was a classified Air Force aircraft. They are decompartimentalized and the left hand don't know what the right and is doing. But there really are only two explanations. Either a human ship or an ET ship."Unidentified Aerial Phenomena"
Sounds like Pentagon-speak for classified aircraft.
Have we reverse engineered some alien spaceship?
Stranger things have (probably not) been known to happen!