On its lightning-fast advance through Iraq, the radical jihadi group the Islamic State of Iraq and al-Sham (ISIS) has captured Mosul, Iraq’s second-largest city; Tikrit, Saddam Hussain’s birth city; and many other towns along the way. Now, with help from former Baathists and Sunni tribal forces, the group is making its way toward Baghdad. ISIS’ astonishing success could be a harbinger of a tectonic shift within the jihadi movement. Namely, ISIS could supplant al Qaeda as the movement’s leader.
This showdown has been several years in the making. The friction between the two groups goes back years. But the relationship did not reach a breaking point until April 2013, when Abu Bakr al-Baghdadi, the leader of ISIS, expanded his group into Syria and attempted to subordinate the local al Qaeda branch, Jabhat al-Nusra (JN), to his own authority. JN rejected Baghdadi’s leadership, and Ayman al-Zawahiri, al Qaeda’s chief, tried to calm the dispute by announcing that JN would remain responsible for jihad in the Syrian arena and ISIS would keep to Iraq. ISIS refused to accept Zawahiri’s decision and continued its expansion into Syria. Along the way, it trampled other Syrian rebel groups, including radical
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