Pages 40-41 from FCO 105259 - South Africa and the Nuclear Situation 1979

This document reports the receipt of indications from satellite-borne nuclear detection instruments suggesting the possibility of a low-yield nuclear explosion in a broad area encompassing the South Atlantic Ocean, Antarctica, southern Africa (including South Africa), and the southwestern portion of the Indian Ocean. The nature of the event is inconclusive, but the indications are consistent with those associated with atmospheric testing of a nuclear device. Further collection activities are being prepared to ascertain the nature of the event. The US government seeks cooperation and any relevant information from the recipient government, including evidence of unusual air or ground activity. The document also mentions a rough map indicating the satellite position south of latitude 40S.