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.
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 . Drone strikes have weakened al Qaeda in Yemen .