Miami : The US Air Force is understood to be developing a spy plane that travels at more than 4,600mph (7,400km/h).
Now, a conspiracy theorist claims he has spotted an image of the mystery craft on Google Earth’s view of Florida.
The satellite image appears to show an object similar to the artist’s impression of the secretive hypersonic plane being developed by defence firm Lockheed Martin.
It comes a day after Lockheed Martin’s secretive Skunk Works unit said it had already finished making the radical hypersonic update of the long-retired Mach 3 SR-71 Blackbird spy plane.
The Google satellite images were compiled in a video by Tyler Glockner, known for uploading images of UFO sightings to his YouTube channel.