MAARET AL-NUMAN, Syria: The rebels' capture of this strategic city was a key success in their advances in northern Syria against regime forces. But it's so far proven an incomplete victory. Maaret al-Numan remains a shell of a city.

One major reason: Rebels have been unable to take a large regime military base on the edge of the city. Artillery fire from Wadi Deif and other nearby government strongholds regularly thuds into its largely empty residential buildings, while warplanes pound surrounding villages. The vast majority of the population has fled and it's too unsafe for them to return.

The fighters have the base surrounded, and deserters have told them the 350 troops from President Bashar Assad's army inside are short on supplies, outnumbered and isolated. But the rebels have supply problems of their own, with few bullets and fewer still specialized anti-tank weapons needed to deal the final blow to the base, where some three dozen tanks and armored vehicles are holed up.

"If I had ammunition, I could take Wadi Deif in 24 hours and stop the destruction of this town," said Sair Mandil, the commander of the local rebels. He spoke from his command post, set up in a 17th century caravan trading post that had been turned into a local museum. The caravanserai's old stone walls can withstand rocket strikes better than the city's more modern buildings.

This is one of dozens of small stalemates across northern Syria that have fueled rebel frustration over the international community's reluctance to provide their fighters with heavier and more weapons. The United States said last week it will begin providing non-lethal aid to the rebel fighters - mainly food and medicine . But rebel commanders say that without stronger arms they cannot take larger military bases and solidify their advances.

Over the past months in Idlib province, where Maaret al-Numan is located, rebels have overwhelmed a string of towns and villages, capturing military checkpoints and installations. But the bigger the base, the harder a nut it is to crack, giving the military a continued foothold.

In that way, Idlib is shaping up much like neighboring Aleppo province, to the northeast. Last year, rebels took over Aleppo province nearly entirely, gaining unquestioned control of towns and border crossings into Turkey. But they have been unable to take a number of key bases, from which regime artillery and relentless airstrikes continue to harry rebel towns. The province's capital, Aleppo city, remains one of the country's bloodiest battlegrounds as rebels and regime forces fight over it.

Rebel control in Idlib is similar. Idlib city, the province's capital, remains almost completely in regime hands, as do some of the province's larger towns. But the pattern is the same: Rebel control spreading, but undermined by the regime's hold on crucial bases.

Perhaps the rebels' biggest victory in Idlib province has been in Maaret el-Numan. The battle for the city began in October, with rebels systematically capturing the army's outposts in the town. The last to fall was an army post in a restaurant on the highway, leaving the town in their control. The city is strategic because it sits astride a major supply route linking the capital, Damascus, with Idlib city and, further to the north, Syria's largest city and commercial hub, Aleppo.

Some small signs of normal life have returned. A handful of shops have reopened. Rubble has been cleared away from most major streets. An Islamic court has been set up to resolve local disputes, one of the few vestiges of any sort of administration.

But only around 3,000 of its estimated 85,000 inhabitants remain in the city, local activists say. There is little electricity and no running water. Most residents have dispersed into the countryside or to refugee camps on the Turkish border.

Sometimes the regime's strikes cause casualties. Latifa Baqoul's two children were caught in a blast at their house in a nearby village in mid-February. Ahmed, 5, manages a brave smile as his parents show journalists the burn covering much of his lower back. But his 4-year-old sister Bushra, wounded in the arm, bursts into tears.

"God stop the planes," their mother sobs.

In the countryside elsewhere in the province, other units have found their progress stalled for lack of ammunition. So they have largely gone into a holding position. On a recent day, a squad from the Knights of the North rebel brigade moved up a rocky hillside to survey nearby regime outposts, probing for any weak points.

"To strike these positions, it will cost us losses. We're going to see if we can take them or not," said the brigade's military leader, a 37-year-old former manager of a cement company who goes by the nom de guerre of Abu al-Yiman. He spoke on condition his real name not be used for security reasons.

Their mission complete, the squad returns to its base in caves of the Jebel al-Zawiya hills. The thick limestone overhead protects against all the heaviest weapons in the army's arsenal, while carpets on the walls keep out the damp.

This unit of the Knights of the North was formed largely by locals in the Jebel al-Zawiya area. In the uprising's early days two years ago, Abu al-Yiman had joined peaceful protests against the regime, but when troops cracked down on the marches, he and others fled to the hills to create the brigade. It remains closely bound by family and local village ties - its political wing is headed by Abu al-Yiman's cousin, who was a businessman in Europe. Old men from nearby villages come to their cave hideouts to pay courtesy visits and roll tobacco together, while men dance the traditional debka to revolutionary songs.

Its non-ideological nature is a contrast to the well-supplied Islamic militant groups, like Jabhat al-Nusra, which have increased their profile in the rebel movement, often by dashing to the scene of crucial battles while local forces hold the line.

One member of the Knights, Abu Yazzan, says he tried a stint with one of the Islamic movements, the Falcons of Syria, but found it to be all, "Zeal, zeal, Islam, Islam." Smoking was banned and members scrupulously obeyed the rituals of the puritanical Salafi movement.

Abu Yazzan, who also spoke on condition he be identified by his nickname for security reasons, said he left to join the more easygoing Knights. Like most Syrian rebels they pray, and many grow heavy beards, but between operations they return to the rhythms of small-town life rather than hard core religious indoctrination. No one objects to the photos of fashion models on young fighters' laptop screensavers or motorcycle seats.

The rebels say they get most of their ammunition from capturing army positions, with a trickle brought from abroad by smugglers and supporters or distributed by the rebel Free Syrian Army's still nascent command. Heavy infantry weapons like wire-guided missiles or recoilless cannons, which are capable of punching through tank armor at long range, are rare.

Their fallback weapon, the handheld rocket-propelled grenade launcher, is useful for short-range urban ambushes. But it's little use in sieges of bases like Wadi Deif.

So for now, they hold. In the deserted buildings outside the walls of Wadi Deif, young rebels squint down the barrels of machineguns fitted through holes in the concrete, looking for any sign of movement inside the complex.

At a checkpoint on the road leading to the base, located about 500 meters (yards) from the edge of the city, a grinning Syrian rebel who goes by the nickname Ziko flips open his PKC light machinegun to show a band of 25 rounds. This is all the ammunition he has.

His comrade Mohammed Shahna points out at the highway toward Wadi Deif.

"If a tank were to come down this road, what could we do?" he asks.