September 11 attacks advance-knowledge conspiracy theories

Various conspiracy theories allege that certain institutions or individuals had foreknowledge of the September 11 attacks in the United States in 2001. Some of the primary debates include whether the Bush administration or the United States Armed Forces had awareness of the planned attack methods, the precise volume of intelligence that American agencies had regarding al-Qaeda activities inside the United States, whether the put options placed on United Airlines and American Airlines and other trades indicated foreknowledge, and why the identities of the traders have never been made public.

Additional facets of the theories include debate as to whether warnings received from foreign agencies were specific enough to have warranted preventive action, whether domestic intelligence about planned al-Qaeda attacks was thorough enough to have mandated intervention, the extent to which the alleged hijackers were under surveillance prior to the attacks, and whether Mossad or the Pakistani Inter-Services Intelligence were aware of an imminent attack.