Halt Memo (DEFE 24/1948/1).
documentedgovernment_studyLandmark High-Strangeness Cases
One-page USAF memo by Lt Col Charles Halt (dated 13 Jan 1981) to UK MoD on the Rendlesham 'Unexplained Lights'; declassified 1983, in National Archives file DEFE 24/1948/1.
The memo is the documentary cornerstone distinguishing Rendlesham from most UFO cases: a formal USAF communication to a foreign defence ministry describing direct observation of unexplained objects by serving military witnesses. It was never classified and opens the digitised MoD file. The MoD concluded the event was of 'no defence significance' and never investigated it as a security matter. It describes lights, depressions, and radiation readings rather than asserting a craft.