On two nights in December 1980, just after Christmas, strange lights were seen in Rendlesham forest, Suffolk, adjacent to the RAF Bentwaters and RAF Woodbridge airbases. The twin-base complex was operated by the American military as part of NATO's front-line defences. On both occasions, American personnel left the Bentwaters base to investigate the mysterious lights in the belief that an aircraft might have crashed. Disoriented and puzzled, their testimony, given sometime afterwards, has contributed to a widespread belief that the airmen had a close encounter with a UFO.

While it was known that the Deputy Base Commander, Lieutenant-Colonel Charles Halt, had sent a memo to the Ministry of Defence (MoD) about the disturbing incidents, he never received any official reply and the Ministry's subsequent denial of - or at least silence on - the incidents fuelled suspicions among UFO believers that the MoD not only knew the truth about UFOs but was covering up prominent cases.