US military chiefs say IS far more difficult enemy than Al-Qaeda.

US defence chiefs have explained in simple terms their conviction that a multifaceted long-term war will be needed, with intervention in both Syria and Iraq, if Islamic State is to be uprooted from those two countries.
IS is greatly rich and well-armed, achieving an independence in both arms and money. They are already a far more formidable foe than their original disapproving parent organisation al-Qaeda ever was, as the US military chiefs acknowledge.