Across Syria, rebel-held areas are dotted with Islamic courts staffed by lawyers and clerics, and by fighting brigades led by extremists. Even the Supreme Military Council, the umbrella rebel organization whose formation the West had hoped would sideline radical groups, is stocked with commanders who want to infuse Islamic law into a future Syrian government.

Nowhere in rebel-controlled Syria is there a secular fighting force to speak of.

This is the landscape President Obama confronts as he considers how to respond to growing evidence that Syrian officials have used chemical weapons, crossing a red line he had set. More than two years of violence has radicalized the armed opposition fighting the government of President Bashar al-Assad, leaving few groups with both a political vision the United States shares and the military might to push it forward…

“My sense is that there are no seculars,” said Elizabeth O’Bagy, of the Institute for the Study of War who has made numerous trips to Syria in recent months to interview rebel commanders.