For the past two days, rebels backed by Turkey and the US in northern Syria have been fighting for their survival against the self-proclaimed Islamic State.

With support from Turkey and the US-led coalition, including cross-border shelling and air cover, rebels in the northern province of Aleppo have been fighting for months to clear the Islamic State (IS) from the Aleppo countryside, the jihadist organization's last connection to the Turkish border.

On Friday, IS punched through rebel territory north of Aleppo, cutting off a key rebel supply route from Turkey to rebel territory. Rebels in one town along the supply route, in Marea, have now been cut off from their connection resupply and reinforcements further north in the border town of Azaz, which is near the Bab al-Salamah border crossing with Turkey.Since Friday, IS has launched wave after wave of attacks against stranded rebels in Marea and areas to the north.

Yet even before IS launched its latest attack, the battle with IS was obviously faltering. In interviews in Turkey and speaking remotely over social media from inside Aleppo, Western officials and Aleppo rebels and civilians blamed the Islamic State's battlefield successes on everything from rebel dysfunction to insufficient foreign backing, and even on an international anti-rebel conspiracy.

One Aleppo-based Syrian journalist in the Turkish city of Gaziantep said rebels' foreign backers have ordered them to wage a Sisyphean fight for the same handful of towns, which rebels have repeatedly taken from IS but have then been unable to hold.

"[Rebels] get the order, 'Go out, we'll support you,'" he said under condition of anonymity so he could speak more freely. "So Turkey helps out and shells, and [rebels] enter the village. Daesh [IS], meanwhile, immediately withdraws from the village as soon as there's American airstrikes and Turkish shelling. So [rebels] liberate it, then two days later, Daesh attacks and takes it back."

Inside Aleppo, anger had been mounting over a battle some Syrians believe is in the service of foreign agendas, and whose only tangible result seemed to be more rebel wounded and dead.

"There's been a lot of frustration," the journalist said. "[Residents of north Aleppo] are surrounded, and they've been left to their fate."

Rebels have been bottled up around Azaz and the Bab al-Salamah crossing since February, when the Syrian regime's forces cut the road linking the border with the rest of opposition-held northern Syria. Simultaneously, the Syrian Democratic Forces (SDF) in Aleppo's neighboring Afrin enclave seized a number of other towns from rebels, leaving rebels caught between the SDF and IS.

The SDF is led by the Kurdish People's Protection Units (YPG), the Syrian affiliate of the Kurdistan Workers' Party (PKK), although it also includes other, smaller allies. The PKK is now waging an insurgency against Turkey to the north. The SDF now controls much of Turkey's Syrian border, and Turkey refuses to allow the SDF to take more of it, including IS-held eastern Aleppo province, due to its aversion to allowing the Kurds to expand their territory.

Instead, Turkey and the US-led coalition have backed the Arab and Turkmen rebels around Azaz in the hopes that they could push east and capture those IS-controlled parts of Aleppo province. IS's regular shelling of the Turkish town of Kilis from inside Aleppo province has only lent more urgency to the internationally backed rebel push.

Local rebels have coordinated through a joint "operations room" in the border town of Hawar Kilis, said Colonel Ahmed Uthman, military commander of an Aleppo rebel faction Firqat al-Sultan Mourad. Speaking to VICE News in an office in the Turkish city of Gaziantep, Uthman said the operations room is split into three rebel blocs, each responsible for a section of northern Aleppo province. Each bloc includes embedded units that graduated from the Pentagon's "train and equip" program and that are responsible for coordinating airstrikes with the international coalition.

"These trained factions — like [Liwa] al-Mutasem and [Firqat] al-Hamzeh — coordinate, but they're not able to act on their own, so you need al-Sultan Mourad," Uthman said. "They don't have many men. As for al-Sultan Mourad, it's a force on the ground. So al-Mutasem and al-Hamzeh arrange the air cover, and we coordinate closely with them."

Turkey has also facilitated the movement of rebel reinforcements to northern Aleppo province through Turkish territory, Uthman said.

Uthman and others said international backers had not provided rebels with the support they most needed.

IS, they said, has seeded the villages it surrenders to rebels with improvised explosive devices (IEDs), some made with plastic bottles in order to not set off metal detectors. IS has left stay-behind "sleeper" fighters among civilians in rebel-captured villages and, using thermal and night vision goggles, launched nighttime attacks on rebels who are blind in the dark. IS has also regularly peppered rebel positions with suicide car bombs.

Rebels said they needed night vision goggles, mine clearance vehicles, and anti-tank weapons that could pick off car bombs at a distance.

"All the areas in the Aleppo countryside are farmland, and these crops can sometimes be more than a meter [three feet] tall," said Nasser Bilal, spokesman for Pentagon-trained unit Liwa al-Mutasem. "That allows Daesh to sneak up, and of course the Free Syrian Army lacks thermal vision goggles."

Uthman said his requests for mine clearance vehicles had been declined on the grounds that America classified those vehicles as "lethal weapons" and refused to provide them.

"They gave us [handheld] minesweepers, which don't do the job," he said. "With one of those, you can uncover IEDs in a room or two, a small area. But a big area like a village, you can't do it with one of those."

"I have more than 180 martyrs, and 80 percent of them are from IEDs," Uthman said.

Spokespeople for the international coalition and the Turkish Ministry of Foreign Affairs did not respond to requests for comment.

Yet international support aside, the more than 30 rebel factions operating in this tiny pocket in northern Syria have also suffered from problems of their own making.

Aleppo residents emphasized that there were rebel factions fighting IS honorably. But others, according to local sources and Syrians' angry posts on social media, had descended into criminality and dysfunction. One major faction, interviewees said, was so preoccupied with its own internal fissures that until recently it declined to fight IS. Rebel failures to more aggressively pushback against IS around Marea meant that the flank of a rebel offensive along the border strip in April was left fatally exposed, and the rebels' impressive gains quickly collapsed. Other factions' fighters have returned home from the fronts at night, leaving their positions undefended against IS.

"For most of these factions' commanders, this is just a desk job," wrote Azaz-based cleric Yasser Abu Omar on Twitter. "They come in from Turkey in the morning and go back at night, and they don't care if the area falls or not."

"You factions fighting Daesh in the north, you've divided us and wasted the prestige and reputation of the Free Syrian Army," wrote Azaz activist Mahmoud Hassanou on Twitter. "You've made people disgusted with the revolution and with revolutionaries."

Yet both Hassanou and Abu Omar said they mostly blamed the international backers of the local rebel factions for the rebel failures. They and other Syrians said they were keenly aware that Aleppo's rebels were being measured against the SDF and Kurdish YPG.

"People here understand that America wants the area to fall to Daesh, so it can then destroy Azaz on top of Daesh and these terrorist PKK can advance and take the area," Abu Omar said.

Northern Aleppo province "has been a killing field, but it's been necessary," said the journalist. "Because if you leave your place and don't fight Daesh, then the Kurdish factions will take your place, and Syria will be partitioned thanks to them."

The SDF in neighboring Afrin is watching northern Aleppo province closely, an SDF commander said.

"We'll only get involved if we have to," said Ahmad al-Sultan, a member of the SDF's leadership and a commander in a largely Arab SDF faction. "Right now, we're defending our fronts. Currently, Daesh is on the brink of entering Azaz. If Daesh enters Azaz, we won't stay with our hands tied."

"The factions in the northern countryside have clearly failed, by every standard, and in spite of the volume of logistical and other support [they received]," Sultan said over the messaging app WhatsApp.

Asked if some Aleppo factions might join the SDF, Sultan said the SDF was already coordinating with some north Aleppo brigades but declined to name them. On Saturday the SDF reportedly facilitated rebel movement to and from Marea in exchange for control of a neighboring town.

If the northern Aleppo rebels are defeated, their international patrons may have no choice but to support the SDF against the Islamic State in eastern Aleppo province.