The rising status of Islamists among the rebel groups has happened in part because the FSA depends on the work carried out by Jabhat al-Nusra. “Jabhat does the storming, and the FSA follows,” said Tony Badran, research fellow at the Foundation for the Defense of Democracies. “These are hard-charging, disciplined fighters, who seem to have won the sympathies of the population in a number of places. Unlike some of the FSA units they don’t seem to bother the local communities.” Jabhat al-Nusra has also fought against Kurdish groups, as has the FSA. At other times, the FSA has teamed up with Kurdish units to take on the regime. And there have been bouts of intra-Kurdish fighting.

What started as a war between the Alawite minority regime and Syria’s Sunni Arab majority in November 2011 has now dragged in other sectarian and ethnic groups, and the battle lines are no longer clear. “It’s a sectarian war, but there is plenty of switching sides, with shifts depending on given interests,” said Badran.

The key difference between Syria’s civil war and the region’s other recent, major sectarian conflicts is that there is no larger actor managing the balance of power. Though the Bush Administration made many mistakes in Iraq, the battle would not have tipped against al-Qaida without the U.S. military mediating that country’s sectarian conflict. In Lebanon’s long civil war (1975-1990), Syrian President Hafez al-Assad played a custodian of sorts, since he had the most invested in the result, backing a number of militias while taking the fight to others—and not infrequently switching sides.

No one is playing a similar role in the war for Syria.