“A senior law enforcement official said that 17 of the 19 hijackers were not known to intelligence or law enforcement officials before the Sept. 11 attacks. Two of the hijackers, Khalid al-Midhar and Nawaf alhamzi, were placed on the government’s official watch list for suspected terrorists before the attacks.”
– Lowell Bergman and Don Van Natta Jr., “Agents Pursue German Leads On Terror Trail,” The New York Times, Sep. 25, 2001