“On October 7, 2001, Osama broke with Al Qaeda’s tradition of never claiming responsibility for attacks and praised the 9/11 operations, vowing that the United States would never ‘enjoy security’ till ‘infidel armies leave’ the Gulf. [Al Qaeda second-in-command Ayman] Al-Zawahiri called on Muslims everywhere to join in their battle against the United States while his spokesman and confidant, Sulaiman Abu Ghaith, announced that Muslims were duty bound to attack US targets worldwide.”
– Rohan Gunaratna, Inside al Qaeda, Page 111