There is nothing to disclose. There have been lots of reports over the years, but there has NEVER, EVER been a verified, confirmed, unequivocal sighting of any space ship or life form from another planer. Never. Period. Full Stop.
Almost everything that people claim is a UFO is in the category of aircraft of some sort, stars, planets, satellites, weather phenomenon, Chinese lanterns or is a deliberate hoax.
As an illustration of how easy it it to be fooled, on one of my morning walks recently, I saw lights in what looked like a formation of 4 of something in the sky. The lights were clearly not from a commercial plane or any helicopter - I see plenty of those. They appeared to be very high and were moving very slowly and curiously, maintaining a very tight formation, but clearly not all attached to the same craft - or whatever. It took me about 10 seconds to figure out that those lights were the reflection off of the underside of wet power lines from the outside lights of a house farther down the road.
If I was prone to believing in aliens, I could have called the police with a report of 4 unidentified space craft - thus generating another erroneous report of a "sighting" of aliens.