Pearl Harbor Advance-knowledge Conspiracy Theory - Ten Official U.S. Inquiries

Ten Official U.S. Inquiries

The U.S. government made nine official inquiries into the attack between 1941 and 1946, and a tenth in 1995. They included an inquiry by Secretary of the Navy Frank Knox (1941); the Roberts Commission (1941–42); the Hart Inquiry (1944); the Army Pearl Harbor Board (1944); the Naval Court of Inquiry (1944); the Hewitt investigation; the Clarke investigation; the Congressional Inquiry (1945–46); a top-secret inquiry by Secretary of War Henry L. Stimson, authorized by Congress and carried out by Henry Clausen (the Clausen Inquiry; 1946); and the Thurmond-Spence hearing, in April 1995, which produced the Dorn Report. The inquiries reported incompetence, underestimation, and misapprehension of Japanese capabilities and intentions; problems resulting from excessive secrecy about cryptography; division of responsibility between Army and Navy (and lack of consultation between them); and lack of adequate manpower for intelligence (analysis, collection, processing).

Investigators prior to Clausen did not have the security clearance necessary to receive the most sensitive information,. Clausen claimed that, in spite of Secretary Stimson having given him a letter informing witnesses that he had the necessary clearances to require their cooperation, he was repeatedly lied to until he produced copies of top secret decrypts, thus proving he indeed had the proper clearance.

Stimson's report to Congress, based on Clausen's work, was limited due to secrecy concerns, largely about cryptography. A more complete account was not made publicly available until the mid-1980s, and not published until 1992. Reaction to the 1992 publication has varied. Some regard it as a valuable addition to understanding the events, while one historian noted Clausen did not speak to General Walter Short, Army commander at Pearl Harbor during the attack, and called Clausen's investigation "notoriously unreliable" in several aspects.