Following Osama bin Laden’s February 23, 1998, fatwa calling for the killing of Americans, “Osama also had received the support of forty Afghan clerics who issued a fatwa calling for a jihad against the Americans on March 12 [1998], and another similar fatwa by a group of Pakistani-based clerics, signed by Sheikh Ahmed Azzam, in late April 1998. Critics who claimed that Osama had no legal authority to issue at fatwa were neutralised when these two bodies issued similar fatwa.”

 – Rohan Gunaratna, Inside al Qaeda, Pages 46-47