State Department report says al Qaeda affiliate in Yemen particularly lethal . Al Qaeda Central has had difficulty commanding influence and ordering directives . The civil war in Syria continues to be a magnet for extremists . NEW : A new study by the Combating Terrorism Center at West Point finds that more than half of all terrorist attacks since 9/11 have been carried out with improvised explosive devices, or IEDs.
State Department report says al Qaeda affiliate in Yemen particularly lethal . Al Qaeda Central has had difficulty commanding influence and ordering directives . The civil war in Syria continues to be a magnet for extremists . NEW : Terror attacks increase in 2013 ; More than 9,700 recorded resulting in more than 17,800 deaths .