Here are two laws that supervise UFO encounters and exotic material recovery. It shadows project Blue Book and certainly pinpoint a real recognition of a real phenomena by the US authority of the time.
Air Force Regulation 200-2 : This Regulation establishes procedures for information and evidence material pertaining to unidentified flying objects and sets forth the responsibility of Air Force activities in this regard. It applies to all Air Force Activities.
JOINT ARMY-NAVY-AIR FORCE PUBLICATION 146