What we know from decades of UFO government investigations

This image released by the U.S. Department of Defense shows a 2004 encounter between two Navy fighter jets and an unknown object near San Diego. But are UFO sightings like this one a sign of extraterrestrial life, spies from a rival nation—or just weird weather?
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This article has been archived by Conspiracy Resource for your research. The original version from National Geographic can be found here.