A Mehdi Army fighter loyal to Shia cleric Moqtada al-Sadr gestures during military-style training in Najaf, June 19, 2014.
Alaa Al-Marjani / Courtesy Reuters

The news that the Islamic State of Iraq and al-Sham (ISIS) had taken control of Mosul on its way toward Baghdad caught Americans by surprise. 

It shouldn’t have. More than a third of all ethnic civil wars restart within five years. And about a third of all post-conflict power-sharing agreements fail within the same time frame. For example, in Angola, concessions to increase representation through multiparty elections led to a new bout of war in 1991. In Afghanistan, the losing side remobilized in 1992, 1996, and 2001. And in Sri Lanka, a 2002 ceasefire collapsed in 2006.

In other words, today’s reignition of the 2006–07 Iraqi civil war fits a well-established pattern. And that pattern has several implications for U.S. strategy in the region. 


Peace after an ethnic civil war is so tenuous because violence reifies ethnic identities and post­–civil war politics is inevitably cast along ethnic lines. This creates

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  • KEVIN RUSSELL is a Ph.D. Candidate in Political Science at Yale University. He was an Iraq policy analyst for the Department of Defense from 2006–08 and State Department Governance Specialist in 2008–09. NICHOLAS SAMBANIS is Professor of Political Science at Yale University.
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