To commemorate 9/11 , al Qaeda 's leader issued new threats . Ayman al-Zawahiri called on his followers to `` land a large strike '' Al-Zawahiri has headed al Qaeda , since a U.S. military operation killed his predecessor and al Qaeda 's founder , Osama bin Laden , in May 2011 in Pakistan . He named the Boston Marathon bombings as an example . The attacks were carried out by two brothers who had been radicalized in Yemen and Pakistan.
To commemorate 9/11 , al Qaeda 's leader issued new threats . Ayman al-Zawahiri called on his followers to `` land a large strike '' He named the Boston Marathon bombings as an example . The attacks were carried out by two brothers who had been radicalized in Yemen and Pakistan.