>>115553334 pilots saw something with their own eyes, 1 other pilot saw something on FLIR, and presumably radar operators odd stuff on their screens. It's not inconceivable that they were all seeing different signatures of the same thing.
One consistent thing across all of these observations? The detection of bizarre, erratic movement. My best guess is that what they were seeing wasn't an aircraft but some artificially created plasma excitation that could be moved around rapidly (e.g. by pointing energetic beams at some point in a sky so that they'd dump energy there and create a localised plasma). Presumably this technology would have been created by the US military, an obvious application would be radar spoofing/causing confusion.
Oblique reference to this kind of thing 13 years ago here:
https://www.wired.com/2007/05/plasma-laser-uf/ 
