On April 15, 1987, bin Laden’s mentor Abdallah Azzam published the book Join the Caravan, a call to jihad. In it, he wrote: ” ‘Jihad, which entails donating one’s money and risking one’s life, is an individual duty in every place conquered by the unbelievers, and remains so until every piece of land that was once Muslim has been liberated.’ ”

 – Gilles Kepel and Jean-Pierre Milelli, eds., Al Qaeda In Its Own Words, Page 121