The Flying Saucers are Real is a book that investigates numerous encounters between USAF fighters, personnel, and other aircraft, and UFOs between 1947 and 1950. Keyhoe contended that the Air Force was actively investigating these cases of close encounter, with a policy of concealing their existence from the public until 1949. He stated that this policy was then replaced by one of cautious, progressive revelation. Keyhoe further stated that Earth had been visited by extraterrestrials for two centuries, with the frequency of these visits increasing sharply after the first atomic weapon test in 1945...