AKHTARIN, Syria — The rebel fighters peered through small holes in the wall of the abandoned poultry plant and across the farm fields where forces of the Islamic State had massed.
Hidden here, breathing the rank air, the rebels could see evidence of their foes’ recent victories: U.S.-made Humvees captured from the army in neighboring Iraq and driven almost all the way across Syria, as if the borders between the countries no longer existed.
More than a military advantage, the American vehicles serve as a psychological tool against more moderate Syrian rebels.
In Akhtarin, one village on a 30-mile front line that extends from the Turkish border to Aleppo, rebels buoyed by the arrival of hundreds of reinforcements from neighboring provinces have held off several attacks by Islamic State fighters. But they fear they are outmatched by the extremist group, which is enjoying momentum and the spoils of the Iraq war.
The rebels may soon face another complication. They could find themselves squeezed between the Islamic State, which broke away from al-Qaida, and al-Qaida’s affiliate in Syria, Al Nusra Front, as the two battle for dominance in the global Islamist militant movement.
The Islamic State, emboldened by its swift advance in Iraq — along with allied Sunni Muslim groups it now controls an estimated one-third of that country — and flush with new cash and oil wealth, hopes to push westward in Aleppo province.
As recently as January, several rebel groups had united to expel fighters of the Islamic State — then known as the Islamic State of Iraq and Syria, or ISIS — from parts of northern Syria. But the group’s lightning advance in Iraq and declaration of a caliphate encompassing Iraq and Syria have given it enormous momentum, said Badee Muhammed, a commander with the Islamic Front, a rebel faction that opposes it.
“We were expecting them to return, because we know that their goal is not just Aleppo … their ultimate goal is the entire region,” he said.
Since June, when Islamic State leader Abu Bakr Baghdadi announced the establishment of an Islamic caliphate, the group has consolidated its control over much of the oil-rich eastern province of Dair Alzour. It continues to make gains in Hasakah province in northeastern Syria.
It recently began clashing with President Bashar Assad’s forces. The two sides had so far mostly avoided confrontation, leading many to conclude there was collusion between them to weaken Syria’s various rebel groups.
But last month Islamic State fighters seized two military bases in the north, beheading some government soldiers and displaying their bodies and heads at a busy roundabout. They also captured and briefly held an important gas field in central Homs province.
The Islamic State now controls about a third of Syria, according to the opposition Syrian Observatory for Human Rights.
In Aleppo, rebel groups see themselves as the last line of defense against the territory-hungry Islamic State. Since its resurgence in the province, Islamic State fighters have seized control of only three villages, but rebels doubt they can stem the advance given the imbalance in weaponry.
Even nonlethal equipment gives the extremists an edge. Many of the clashes take place at night, and Islamic State fighters appear to have night-vision goggles. In contrast, their foes say they often are forced to fire blindly at night, wasting ammunition.
“If we don’t get more military aid soon, it is impossible for us to hold them off. I go to the front lines and try to lift the fighters’ spirits, but in the end we have no idea how we’re going to resist,” said Muhammed, the Islamic Front commander, adding that they have received only $200,000 from the Western-backed Supreme Military Council.
“It is fear and a lack of ammunition,” said Abu Hussein Debo, a local commander in Akhtarin. “Because they are coming and slaughtering with no mercy.”
Fighters here have direct knowledge of the public executions and other brutal tactics that Islamic State forces used before they were expelled from the area earlier. And they’ve heard of the recent beheadings elsewhere.
Soon after the Islamic State began seizing territory in Iraq, a map purporting to show the group’s five-year plan was released. It showed the Middle East, South Asia and the northern half of Africa under the group’s black flag.
“The map keeps getting bigger and their goals keep getting more extensive,” Muhammed said. “And if we can’t stand in their way and push them back, that could happen.”
Al Nusra Front might stand in the way as well. The al-Qaida affiliate is an ally of more moderate rebel groups fighting Assad, but it is starting to replicate some of the Islamic State’s strategies in an effort to avoid becoming irrelevant in the global militant movement.
A month after the Islamic State declared a transnational caliphate, Al Nusra said it would eventually announce its own governing entity, an emirate in Syria.
Humam Halabi of Manara Al Bayda, Al Nusra’s media channel, said that could happen within a month, and that in the meantime the group was undergoing an internal restructuring.
The Syrian al-Qaida branch, much like al-Qaida’s central command itself, has been overshadowed by the rapid rise of the Islamic State, which espouses more extreme views and has more social media savvy. Al-Qaida renounced the Islamic State this year after it repeatedly failed to heed orders from Ayman al-Zawahri, al-Qaida’s leader.
“Obviously, Syria has become a battleground between al-Qaida and IS,” Halabi said.
So far, Al Nusra has engaged in heavy clashes with Islamic State fighters only in eastern Syria, where battles have raged over control of oil fields. Many Al Nusra fighters are unwilling to kill fellow Sunni Muslims, but now leaders are taking drastic measures.
Al-Qaida-linked religious leaders have traveled from Afghanistan, Chechnya and Saudi Arabia to persuade them that there is proof that Islamic State fighters are “khawarij” — Muslims who have turned against a rightful leader — and must be fought, Halabi said.
In announcing plans for an emirate, Al Nusra hopes to lure back some of the groups that have pledged allegiance to the Islamic State, as well as attract the foreign fighters who have been drawn to the conflicts in Syria and Iraq.
“The foreign fighters want either an emirate or a caliphate,” Halabi said.
Al Nusra fighters also have reportedly withdrawn from some front lines against Assad’s forces in Aleppo and turned their attention to capturing what the group describes as corrupt rebel groups there and in Idlib province. On July 23, Al Nusra drove out the Western-backed Syrian Revolutionaries Front from Harem, a town on the Turkish border. Not long ago it had fought alongside the group.
When Abu Mohammad Golani, the shadowy Al Nusra leader, recently made an appearance among his fighters in Aleppo, he spoke of battling the Islamic Front and thieves, Halabi said.
Mohammad Sheik, a media activist with the more moderate Islamic Front, said Al Nusra was following the path of the Islamic State by declaring war on criminal elements among the rebels. Before the Islamic State turned on the rebels, it established its reputation by cracking down on theft, kidnapping and other crimes.
“Then they will move on to other (rebel) groups,” Sheik said of Al Nusra. “They want to focus on the military operations that will bring back all the foreign fighters who left.”
Earlier this month, the Dawood Brigade rebel group, which had been allied with the Islamic Front, claimed it was going to reinforce opposition fighters on the front line with government forces attempting to besiege the city of Aleppo. The convoy consisted of about 200 Dawood fighters along with dozens of tanks and other armored vehicles.
Instead of Aleppo, however, it headed east to the Islamic State stronghold of Raqqa province and pledged allegiance to the radical group.
Al Nusra also is feeling the effects of the Islamic State’s momentum. It has suffered a drop in revenue because it has lost control of the oil wells it once held in eastern Syria as some of its groups have withdrawn and others have joined the Islamic State.
“They are trying to regroup and reestablish their financial support,” said Mustafa Sultan, a rebel with the Islamic Front.
Al Nusra also is distancing itself from mainstream rebels, especially those allied with Western backers, in an attempt to regain credibility. It recently withdrew from the Sharia Committee, a legal authority in Aleppo it helped establish, and has formed its own version, Halabi said.
The al-Qaida group might soon also withdraw from a joint operations room, which has coordinated all the opposition battles in Aleppo province in recent months, he said.
But first, Al Nusra plans to form its own army, Halabi said. “An emirate without an army won’t do.”