Back in the 1950's my FIL was working for a un-named company that was cataloging films taken by the military. He had to take the "50 year oath" to not disclose what he saw on those films.
Over 50 years later he was talking to a friend of spouse and told him a story or two. FIL ALWAYS believed there were UFO's. Living among us? I don't know. Based on this family friend FIL mostly saw flying UFO's.