The 9/11 Commission's final report on July 22, 2004 stated that the FBI and Central Intelligence Agency (CIA) were both partially to blame for not pursuing intelligence reports that could have prevented the September 11, 2001 attacks. In its most damning assessment, the report concluded that the country had "not been well served" by either agency and listed numerous recommendations for changes within the FBI. While the FBI has acceded to most of the recommendations, including oversight by the new Director of National Intelligence, some former members of the 9/11 Commission publicly criticized the FBI in October 2005, claiming it was resisting any meaningful changes.

What agencies were to blame for 9/11?