What happened
Underwood's jet carried an ATFLIR targeting pod. He recorded a 76-second infrared clip of a small oblong target that drifts and then leaves the frame to the left. This is "FLIR1". He named it the "Tic Tac", partly from a joke in Airplane! He says it jammed his radar. He did not see it with his own eyes. He told New York magazine in 2019 that he cannot confirm the object actually accelerated as the video seems to show. The clip leaked in 2007, ran in The New York Times in December 2017, and was released by the Department of Defense on April 27, 2020.