Here is one of your UFO's:
Thank you Kelly Johnson and the Skunk Works. It should come as no surprise that UFO sightings proliferated as the US started developing technology like the SR-71 with capabilities that even those in the industry would deem impossible. The US government even encouraged it.
Quick bit of trivia, the SR-71 leaked fuel while on the ground. It wasn't until the fuselage heated at high speeds and expanded as much as a foot during flight that the leaks would seal. It became more efficient the faster it flew, figure that one out.
Amazing considering development started in the late 50's.