On December 2, 2001, al Qaeda second-in-command Ayman al-Zawahiri wrote, in Knights Under the Prophet’s Banner: “Today we are witnessing a new phenomenon that continues to gain ground: young Muslim fighters who have abandoned family and country, neglected wealth, left their studies and jobs to join the battlefields of jihad. …What led us to the conclusion that ‘jihad is the only solution’ was the brutality and injustice of the new Jewish crusade, which treats the Muslim community with utter contempt.”
– Gilles Kepel and Jean-Pierre Milelli, eds., Al Qaeda In Its Own Words, Pages 194-195