Both sides continue to call up reinforcements in the buildup to what will likely be a major showdown. A concern for the rebels: The Liwa Dawud battalion sent to back them up from Idlib has defected and joined IS and may well head their assault in the northern part of Aleppo province. This is now a major concern of the rebel leadership. As the IS menace draws nearer, smaller rebel factions might choose to side with the stronger force and spare themselves a messy and brutal annihilation.

The regime’s forces, backed by various local and foreign militias, have made dramatic gains in the last 10 days, taking the strategic Sheikh Najjar industrial zone to the northeast and planning an imminent push into the infantry school and the Handarat camp. Controlling them would mean that rebel-held parts of Aleppo city would be completely besieged and cut off from their main supply routes in the countryside. It is a strategy previously used successfully by the regime in Homs and Damascus, where it yielded results in the form of localized cease-fires and settlements. At the moment, it seems that unless something dramatic changes on the ground, the regime will manage to accomplish this feat and the rebels are quite helpless to stop it. This point was driven home by the opposition Syrian National Coalition as it met recently in Istanbul to elect a new president and warn of the impending fall of Aleppo to regime forces.

Like a helpless lamb fought over by wolves, Aleppo is the major prize of north Syria, and any side that manages to capture the former industrial hub will almost certainly guarantee eventual victory in this long and bloody conflict. The regime and the opposition know this well, as does IS, which also has its eyes on the prize as it plots to expand the territory of its new caliphate and diversify it economically, bolstering it with large population centers. IS has been in Aleppo before and had a fleeting, tantalizing taste of what lucrative gains can be made by controlling it.

“Our fear now is without reinforcements and more weapons we will lose Aleppo [city] to the regime, and the [countryside] to the Islamic State,” he said.

ALEPPO, Syria — “I have to be honest. It is not looking good,” Aleppan Liwa al-Tawhid commander Abu Hammoud told Al-Monitor when asked about the rebels’ preparedness for assaults on Aleppo by the Syrian regime and the Islamic State (IS, formerly the Islamic State of Iraq and al-Sham).

Aleppo's rebel factions have made attempts to build a unified elite force of 600 men to salvage and protect what areas they still control against both the regime and IS. It's unclear yet whether such a force is any more than ink on paper or whether it will be effective at all, as previous such attempts have been less than successful. In a rather ominous development, Jabhat al-Nusra, the officially sanctioned al-Qaeda affiliate and one of the strongest rebel factions operating in Aleppo, has withdrawn from the rebel Sharia Council it helped create. The Sharia Council was responsible for running affairs in rebel areas, as well as arbitrating in disputes between factions. It's still unclear yet what this move will mean, but many see it as a sign of a weakened organization, driven out of its strongholds in Deir ez-Zor by IS, becoming increasingly paranoid and isolated.

IS continues to push slowly but steadily from its eastern strongholds in Manbij and al-Bab. Its next major assault on the northern countryside will most likely begin with the border town of Azaz, as was the case in September 2013.

The embattled Aleppo rebels are becoming desperate and their leadership nervous. Their losses and setbacks on the battlefield have taken a heavy toll on their morale and cohesiveness on the front lines, which were never really all that steady to begin with, given the fractious and often bickering nature of the various rebel groups.

The two major rebel groups left operating in Aleppo are the Muslim Brotherhood-affiliated and Qatari-backed Liwa al-Tawhid and the al-Qaeda-affiliated Jabhat al-Nusra. They bear the brunt of defending the various front lines around Aleppo province and inside the city itself.

The Aleppo rebels find themselves in a vice, caught between advancing regime forces and a resurgent IS. With regional and global powers jittery by the meteoric rise of IS in Iraq, funds, weapons and men are increasingly harder to come by. The persistent refrain of the rebels since the beginning of the conflict has been: Send us more and better weapons. It's unclear, however, if they would actually make a difference at this stage, and the likelihood that they would fall into the hands of IS is very real, not to mention that any nation sending arms to Aleppo’s rebels would also be de facto directly arming al-Qaeda’s official wing in Syria.

Unless there is a dramatic change of fortune for the rebels on the ground, it's likely that the regime will besiege Aleppo city in the coming weeks, and then force settlements and cease-fires on any remaining rebels still garrisoned inside, as was its successful strategy in Damascus and Homs.

IS will likely push into the north and east countrysides, routing rebels from their strongholds and establishing its authority via rigid and barbaric law, "cleansing" them of any resistance to its rule, marking the end for Aleppo’s rebels.

If Liwa al-Tawhid’s two strongholds of Tall Rifat and Marea fall to IS, then the group is effectively finished. Jabhat al-Nusra will fare no better, as its string of crushing defeats in Deir ez-Zor at the hands of IS means that it has lost many of its men, including those who defected to IS, and important financial resources. The remaining smaller local rebel groups will either be assimilated by IS or completely destroyed.

With the vultures circling overhead, the unhappy residents — what’s left of them — of this once magnificent metropolis now ponder their fate and that of their beloved city. Regardless of which group wins, this city will never be the same again. It will take a decade or more to rebuild and get back on its feet, and maybe a generation or two until the bitter social rifts can heal. But that’s what the Aleppans long for: the end of the war by any means possible, and by whomever.