ASH SHADDADI, Syria – Sitting at the edge of a vast and barren desert in Syria’s gas and oil production region, Ash Shaddadi, a city of 70,000, has become the nightmare that many fear if Syria’s radical Islamist forces triumph in this country’s civil war.

Since mid-February, the city has been under the control of the radical Islamist militia known as Jabhat al-Nusra, or the Nusra Front, which has pledged allegiance to al-Qaida. The spoils of conquest include much of eastern Syria’s petroleum resources: a major natural gas plant here, many oil wells in the countryside of Deir el Zour province to the south and much of the production of grains and cotton.

Nusra, which the U.S. government has branded a terrorist organization, captured Ash Shaddadi from forces loyal to Syrian President Bashar Assad with the help of the pro-Western Free Syrian Army rebels. But the better-equipped Nusra — many of its fighters veterans of battles against U.S. forces in Iraq — took the lead in the four days of fighting, capturing weapons, ammunition and government property.

Today Nusra runs the town. It controls the grain silos, the cotton warehouses, and most important the region’s gas and oil output. Yet the biggest windfall from victory may have been the proceeds from the sale of some 400 major construction vehicles, which they captured when they overran state facilities in January. The sale of the equipment netted 4 billion Syrian pounds, almost $40 million at the time, according to local Free Syrian Army commanders.

Townspeople have taken to the streets repeatedly to protest Nusra’s inability to provide basic services and its claim to piety and religious values while it seizes public property for use as it sees fit.

But the protests haven’t shaken Nusra’s hold on the area, and because Nusra is self-sufficient in Ash Shaddadi, its fighters say there’s no way for outsiders to shut down support.

With Assad’s forces ousted from the area, the United States is their primary foe, Nusra fighters say.

“America is our enemy. They must get out of Iraq, Afghanistan and Egypt, and they must put pressure on Israel,” said Abu al-Walid, 21, a student of petroleum engineering who’s now guarding the Ash Shaddadi gas plant.

How powerful Nusra and similar groups are as a force in the anti-Assad movement is hotly debated in the United States amid concerns that the sudden collapse of Assad’s government would end up placing al-Qaida-affiliated fighters in charge. U.S. Secretary of States John Kerry, in testimony before Congress when the administration was pressing for authorization to launch a strike on Syria, said they made up only a small part of the rebel movement and that moderate rebels, with democratic instincts, were in the ascendancy.

But there’s no doubt that Nusra runs this region and has no moderate rival for influence — and no plans for moderation.

Receiving a McClatchy reporter at the gas plant, Walid and his colleague, Abu Nawaf, 23, gave an unvarnished, if unofficial, description of how Nusra runs the area and what it plans for the future.

Walid said Nusra in Ash Shaddadi consisted primarily of local residents, apparently built on a base of conservative Islamists known as Salafists from a nearby village. Ten percent of the Nusra members here are non-Syrian, mainly Yemenis, Tunisians and Iraqis.

Nusra has been pressing the local population to be more serious about religious observance, Walid said.

People “were far from religion because of the regime,” but now they’re attending mosque more often, “and we have an office to teach and advise them. We are giving courses on the Quran.”

As for democracy, he said Nusra was opposed to elections and that if townspeople insisted on them, Nusra wouldn’t take part. But the movement is willing to allow girls to attend school, including higher education, provided they’re separated from boys.