Struggles between Sunni and Shia forces have fed a Syrian civil war that threatens to transform the map of the Middle East, spurred violence that is fracturing Iraq and widened fissures in a number of tense Gulf countries. Growing sectarian clashes have also sparked a revival of transnational jihadi networks that poses a threat beyond the region.
Islam’s schism, simmering for 14 centuries, doesn’t explain all the political, economic and geostrategic factors involved in these conflicts, but it has become one prism by which to understand the underlying tensions.