General Chassin was the Chief of Staff of the French Air Force, and after the war became NATO's Air Defense Coordinator for all Europe. Just after the war, Chassin and his chief assistant, Colonel Clerouin, became extremely interested in the UFO problem, going even so far as authoring articles in support of investigating them. Chassin argued that an international program of UFO observation and data-gathering should be begun and that this was critical to avoid confusion between sightings of UFOs and enemy missiles (UFOs and Accidental War). When he was asked if he then thought that the UFOs could be extraterrestrial devices, he responded simply: Why not? (Unknown source)  In 1958 he penned the foreword for Aimé Michel's book "Mysterieux Objects Celestes" (USA edition: "Flying Saucers and the Straight Line Mystery"). In 1964 he accepted the presidency of the UFO organization GEPA [Groupement d'Etudes des Phénomènes Spatiaux], which he co-founded in 1962, and remained in that position until his death in 1970.  (Eduardo Russo)