FBI had information about Pearl Harbor attack four months before Japanese offensive
One of the major conspiracy theories that has stood the test of time is the "Pearl Harbor advance-knowledge conspiracy theory," wherein the argument is that US Government officials had advance knowledge of Japan's December 7, 1941, attack on the island in Hawaii.
The attack will always be remembered as a dark day for the US, but for many the "surprise attack" on Pearl Harbor may not have been such a surprise after all.
Episode 4 of Smithsonian Channel's 'America's Hidden Stories', "Pearl Harbor Spies" mines declassified documents to make a case that the FBI was well aware of Pearl Harbor being a probable target during World War 2, but the agency was unable to prevent it from happening.
The documentary reveals that the FBI was aware of the existence of an extensive network of Japanese and German spies who had allegedly been present in the United States for around 20 years prior to the attack.
According to information gathered, it is believed that agencies knew of the interest of these secret operatives in the US Pacific fleet.