From Wikipedia

FDR Pearl Harbor Conspiracy

The Pearl Harbor advance-knowledge debate is a dispute over what, if any, advance knowledge American officials had of Japan's December 7, 1941 attack on Pearl Harbor.

Ever since the Japanese attack there has been debate as to how and why the United States had been caught off guard and how much and when American officials knew of Japanese plans for an attack.

Several writers, including journalist Robert Stinnett and former United States Navy Rear Admiral Robert A. Theobald, have argued that various parties high in the U.S. and British governments knew of the attack in advance and may even have let it happen or encouraged it in order to force America into war via the "back door." Evidence supporting this view is taken from quotations and source documents from the time and the release of newer materials.

Examination of information released since the War has revealed there was intelligence information available to U.S. and other nations' officials. Rather than attribute the lack of preparedness at the base to failure-to-process, some have argued that the U.S. must have had some degree of advanced knowledge of the attack.