Japan was using Pearl Harbor for pilot bombing-attack training for at least that long before the actual attack, they had a full size mock-up apparently. None of this was a big secret.
“Japan was using Pearl Harbor for pilot bombing-attack training for at least that long before the actual attack, they had a full size mock-up apparently. None of this was a big secret.”
Japan had been training for combat with the U.S. Navy ever since the Russo-Japanese War. The fact that the naval air forces were preparing for a strike against the U.S. Navy was expected, whether or not such training was novel or routine. Even if you had a U.S. naval attaché invited to the Japanese training exercise, the choice of target would have not excited too much surprise or concern. What made the difference was the U.S. Navy’s ignorance of the secret Japanese preparations for shallow running aerial torpedoes and operational underway refueling methods. An astute U.S. naval attaché witnessing the experimental aerial torpedoes may have focused the attention of U.S. naval leaders upon the risks of such an attack in Pearl Harbor, but the Japanese successfully kept such secret preparations away from the prying eyes of U.S. intelligence operations.