Sectarian rifts are almost as old as Islam itself. They surfaced in 632, shortly after the death of the Prophet Muhammad, when Muslims disagreed over who should succeed him. Although the original sectarian split was violent, Islam’s two major branches — Shiism and Sunnism — have co-existed peacefully more often than not over the centuries. But recently, sectarian tensions once again have erupted into full-scale violence in the wake of the U.S. invasion of Iraq and last year’s Arab Spring democracy movement. The volatile situation is not just about theology. Competition for power and privilege intensifies the hostility and distrust. In postwar Iraq, sectarian attacks killed 325 people in July, the highest monthly toll since August 2010. Currently, the epicenter of the sectarian crisis is Syria, where the Sunni opposition is battling the Shiite Alawite regime of Bashar Assad. Experts fear the violence could engulf significant parts of the Middle East. Meanwhile, other countries have lined up on either side of the fight, with Iran, Russia and China supporting the Syrian regime and Saudi Arabia, Turkey, the Gulf States and the West supporting the rebels

Leda Hartman is a nationally award-winning print and public radio journalist who specializes in global affairs. Her articles have appeared in The New York Times and The Christian Science Monitor, and her radio stories have aired on programs such as "Morning Edition," "All Things Considered," "Marketplace" and "The World." She also was an editor for two public radio global affairs programs, "Lattitudes" and the "World Vision Report."