In Syria's largest city, Aleppo, rebels aligned with al-Qaida control the power plant, run the bakeries and head a court that applies Islamic law. Elsewhere, they have seized government oil fields, put employees back to work and now profit from the crude they produce.
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 Barack 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 Assad, leaving few groups with both a political vision the United States shares and the military might to push it forward.
Among the most extreme is the notorious Al Nusra Front, the al-Qaida-aligned force declared a terrorist organization by the United States, but other groups also share aspects of its Islamist ideology in varying degrees.
"Some of the more extremist opposition is very scary from an American perspective and that presents us with all sorts of problems," said Ari Ratner, a fellow at the Truman National Security Project and former Middle East adviser for the State Department. "We have no illusions about the prospect of engaging with the Assad regime - it must still go - but we are also very reticent to support the more hard-line rebels."
Of most concern to the United States is the Nusra Front, whose leader recently pledged fealty to al-Qaida's top leader, Ayman al-Zawahri, Osama bin Laden's longtime deputy. In the oil-rich provinces of Deir al-Zour and Hasaka, Nusra fighters have seized government oil fields.
"They are the strongest military force in the area," said the commander of a Hasaka rebel brigade reached via Skype. "We can't deny it."
But most of its fighters joined the group for the weapons, he said, not the ideology, and that some left after discovering the al-Qaida connection.
"Most of the youth who joined them did so to topple the regime, not because they wanted to join al-Qaida," he said.