Bob Lazar worked at Los Alamos. He then worked at area 52 (beyond Groom Lake) studying the gravity altering system in a “craft” that he was not sure of the origin.
Lazar stated he was ONLY allowed to work on this one system of the craft. He worked with one other person. Other two person teams studied other systems.
By altering the gravitational field around the craft it could fly at much higher speeds than anything the USA could produce.
It also had the ability to change direction dramatically almost instantaneously.
Then there is this:
“Zero Point - Classified Anti Gravity Craft - UFO Full Documentary by James Allen”, Film Maker (poisoned) as told by Mark McCandish, USAF Illustrator, (suicide)
https://www.youtube.com/watch?v=NBdS8jiTM6E