"[Your information is] too precise, too complete to be believed. The questionnaire plus the other information you brought spell out in detail exactly where, when, how, and by whom we are to be attacked. If anything, it sounds like a trap."
FBI response to the top British spy, Dusko Popov (code named "Tricycle") on August 10, 1941, dismissing Popov's report of the complete Japanese plan for the attack on Pearl Harbor.
Pearl Harbor: The Verdict Of History by Gordon Prange, appendix 7 published in 1986. Based on records from the JOINT CONGRESSIONAL COMMITTEE on the Investigation of the Pearl Harbor Attack, Nov 15, 1945 to May 31, 1946.