With the global focus on the battle against the Islamic State of Iraq and Syria (ISIS) in the east, rebel groups fighting Jabhat al-Nusra on Syria’s southern front have been receiving increased support from Western and Arab allies.

The National reports that moderate rebel groups have made sizable advances in Quneitra province, now controlling more than three-quarters of the long-disputed territory. The province could be a link between rebels in the mountainous south and their comrades in and around Damascus.

Jabhat al-Nusra, the Syrian arm of al-Qaida, has maintained a sizable presence in the south, leading to the Israeli border in the Golan Heights, where earlier this month it captured and held more than 40 U.N. peacekeepers. Analysts say its position in the south looks increasingly shaky with the increase in outside support for more moderate groups like the Free Syrian Army.

We asked Faysal Itani, a fellow at the Atlantic Council who studies the military situation in Damascus and on the southern front, to weigh in on the inter-rebel dynamics there and Nusra’s changing role in the battle.

Syria Deeply: How is the ground situation changing to the south of Damascus?

Faysal Itani: It’s an interesting dynamic, very different from what’s happening in the north. Southern insurgent groups are trying to advance the front up to the southwest approach into Damascus. Whether or not this is coordinated with the new pressures that Nusra and the Free Syrian Army (FSA) are currently putting on Hama, I don’t know. But it’s strategically valuable in and of itself because it reopens what became a stagnant front in the areas southwest of Damascus.

Now we’ll be looking at how this breaks down in two ways: in terms of the division of power between Nusra and everyone else, and how it reflects the relationship between these insurgent groups and the Jordan-based command and control center that coordinates and supplies these rebel groups in the south.

We know that the relationship between the CIA, Jordan and southern brigades has been relatively good, but once Nusra enters the equation it becomes a bit more complicated. There are two theories about Nusra’s current role in the south.

One is that the Americans, Qataris and Saudis have all converged on the idea that Nusra needs to be pushed out of the south entirely, and that whoever is still reconcilable in the group needs to be reached out to – and whoever isn’t needs to be shut out of the arms stream. That seems to mean taking control of which rebel groups get what assistance, and the dissolution of arms to commanders in the field.

The other, conspiratorial take on it is that Nusra is also receiving support from a coalition of actors including the Qataris. I don’t think so, I think [these powers’ support of other rebel groups] is meant to shift the balance of power away from Nusra and limit their power in the south. Rebel brigades there are not currently in a position to take on Nusra. Their eyes are on taking the battle to Damascus, and not on displacing Nusra.

Nusra is a complicated beast. We don’t know which way factions within it lean or even what their exact ideology is. And their relationship with other rebel groups is a work in progress.

Syria Deeply: Is anyone in the south worried about an ISIS advance, and would any of the rebel groups there ever be considered to be U.S. ground partners?

Itani: It’s a function of the geography of this conflict – ISIS is not a major issue in the southwest, but it’s going to be an issue as this all progresses and if the rebel groups involved come into contact with ISIS. If those groups continue to move north into Qalamoun and if they make advances into the areas northeast of Damascus, suddenly they’re face to face with ISIS.

I’d assume that would mean conflict. I don’t see these groups reconciling with ISIS, particularly in the south where if rebels have the advantage, they can spare some capacity to make sure that this theater continues to belong to them.