Raytheon, Northrop and Lockheed have Been making manmade replicas for years and using them for their own purposes. That’s the majority of what people are seeing and identifying as UFO’s. Dr. Scott Greer speaks extensively about it in a two part interview with Shawn Ryan on his Vigilance elite podcast.
I'm not sure what to make of Greer lately. He's all alone in his theories and is angry as hell at the rest of the UFO "community."
He has become something of an enigma. Some people are loyalty to him and others call him a charleton and narcissist.