In an undated handout image taken from a video released by the Defense Department's Advanced Aerospace Threat Identification Program, a 2004 encounter near San Diego between two Navy F/A-18F fighter jets and an unknown object. UFOs have been repeatedly investigated over the decades in the United States, including by the American military.

U.S. Department of Defense via The New York Times

In an undated handout image taken from a video released by the Defense Department's Advanced Aerospace Threat Identification Program, a 2004 encounter near San Diego between two Navy F/A-18F fighter jets and an unknown object. UFOs have been repeatedly investigated over the decades in the United States, including by the American military.