"Enigma of the Flying Black Triangles"

Reports of huge flying black triangles have been part of the UFO phenomenon since the late 1980's.  There are many credible pictures and even more eyewitness reports, with a huge flap occurring in 1997, where one of the best examples occurred in the Nevada area as several media outlets have produced investigative reports claiming that something very real and out of the ordinary occurred.  As expected, the U.S. government stated that the entire event was the result of A-10 exercises with flares and nothing more. Some eyewitnesses have reported seeing these triangles in the daylight claiming to see USAF markings!  Interestingly, those to whom serious studies and follow-up are done suggest that some are indeed of Alien origin and our government has their own "copy-cat" versions, so some sightings could be of Alien origin and others ours.  However, when they behave in super exceptional fashion that defy gravity and the like, it is hard to imagine that America has been able to meet or exceed the capabilities of the alleged "Visitor's" Crafts. Naturally, this is all speculation and it is up to the individual as to what he/she wants to believe.  Are we being visited by UFO's?  What are the Flying Black Triangles and are they REAL?  What do you think?