the pentagon and dia released a cluster of decades-old ufo documents this week, including 1947 metal-fragment files and a dia memo calling a 1976 iranian f-4 sighting a legitimate case for study, while congress members separately announced a possible mkultra document release and a hidden 1952 briefing tape. in the same window, the us government sealed 23,000 acres around area 51 including the last remaining civilian viewpoint, closing public access even as historical files open.