Whether ISIS holds on in Yarmouk or not, its southward expansion is a further sign that fighting the group in Iraq and eastern Syria will not be enough.
During the first week of April, the "Islamic State"/ISIS captured as much as 90 percent of the Yarmouk Palestinian refugee camp in southern Damascus -- an important and somewhat surprising development in the protracted struggle for the Syrian capital. Previously, the group had a presence in al-Hajar al-Aswad just south of the camp but was not considered a dominant force in the Damascus area. Although the most recent reporting indicates that ISIS is now being pushed out of the camp, its sudden eruption as a significant military factor near the regime's heart poses challenges to Bashar al-Assad's forces as well as the various rebel groups operating in the area.
The advance into Yarmouk camp also represents the strongest ISIS encroachment into southern Syria thus far. Other countries have been working to keep the group out of the south even at the cost of tolerating al-Qaeda affiliate Jabhat al-Nusra (JN), which has been fighting alongside Islamist and more moderate factions in the area. Success or failure in Syria's largest Palestinian camp could reverberate politically elsewhere in the country. In addition, the situation is another sign that ISIS and jihadist groups in general are expanding their hold even as the United States bombs ISIS targets in Iraq and eastern Syria. Regardless of the final outcome in Yarmouk, the current trendlines raise the question of whether American military strategy against ISIS -- coupled with the lack of a robust strategy for Syria -- is helping to create a political context for the group's expansion west and south.
The Yarmouk camp is only six kilometers from the Damascus city center and regime-controlled areas. Since at least late 2012, it has been part of the complex battle that the regime and rebels have waged for the capital and its suburbs. To reassert control in the camp, the regime has besieged, bombarded, and periodically assaulted it several times since 2012, achieving only modest success while brutalizing the civilian population.
The latest battle is part of the longstanding ISIS effort to establish an effective presence in the south, but the circumstances under which it began are unclear. It may have been a result of local rivalries and incidents rather than a grand strategic move by any party. Initial fighting erupted on April 1 when ISIS attacked the camp's main Palestinian armed faction, Aknaf Bayt al-Maqdis. ISIS forces were compelled to retreat at first, but they reentered the camp on April 3 and began driving Bayt al-Maqdis back. By April 4, ISIS reportedly controlled as much as 90 percent of the camp.
The operation may have been aided by JN, which reportedly allowed ISIS fighters to pass through its checkpoints to reach the battle while blocking certain rebel groups from joining the fray. For their part, the Palestinian fighters are said to have received assistance from JN rivals in the southern Damascus area, including the Syrian rebel group Jaish al-Islam. Pro-regime forces have also reportedly been involved in the fight, including Palestinians from the Popular Front for the Liberation of Palestine-General Command (PFLP-GC) and Fatah al-Intifada. The regime has conducted a number of airstrikes on the camp as well, though the targets of these strikes are unclear.
Fighting continues as of this writing, producing a very unclear situation on the ground. The camp now appears to be divided, with ISIS, regime-aligned forces, and various Palestinian and Syrian opposition elements controlling different sectors.
A key question is whether ISIS can sustain its positions in the camp in the face of resistance on several fronts. As mentioned above, the group is reportedly being pushed back by either Palestinian or Syrian opposition forces. Whatever the case, the longer ISIS is present, the more it will be able to prepare defenses and eliminate rebel leaders and groups. And if it establishes control in the area, it would be right in the middle of the protracted fight for Damascus.
The ISIS relationship with JN is important in this context. If ISIS can secure JN's cooperation -- whether active or passive -- its ability to maintain and expand local control will increase. Fighting in Damascus is also important to ISIS politically. Operating in remote Raqqa or Deir al-Zour is one thing; fighting in the capital is quite another. Enduring success in the area could boost the group's image and recruiting prospects, especially in light of recent setbacks in Iraq.
For the Palestinian and Syrian elements opposing the regime, the ISIS advance in Yarmouk is a substantial threat and complication. Already facing significant pressure from Assad's forces, they must now contend with aggressive jihadist opponents. Any rebel operations in the area will have to take ISIS into account, whether as a potential opponent, an obstacle, or perhaps even an ally.
For the regime, the Yarmouk situation presents both threats and opportunities, further illustrating Assad's complex relationship with ISIS. The threat is that ISIS is now only a few kilometers from the presidential palace, and the group has shown that it is capable of giving regime forces a tough fight when it so chooses. To eliminate this threat, the regime would have to devote significant forces and probably accept substantial losses. For now the regime seems focused on combatting ISIS elements in the camp, primarily using allied forces. Yet Damascus has been quite supple in dealing with the group in the past, and it could shift focus at any time. For example, it may come to see the ISIS presence as a benefit in its struggle to pacify the capital area; if so, the regime could seek an accommodation with the group that allows both to concentrate their efforts against Syrian and Palestinian opposition forces, as they have done in other areas.
Overall, the Yarmouk situation is the latest sign that ISIS is extending its reach in opposition-controlled areas of Syria where conditions for civilians are desperate, the international community has failed to provide protection, and more moderate factions do not receive sufficient material and political support. The group's ability to pull other factions into its ranks has allowed it to expand quickly in political vacuums, with unclear and potentially destabilizing consequences. If regime forces push ISIS out of the camp, it could spur yet another call to battle for foreign fighters or other ISIS supporters. And if the group holds on in Yarmouk, it will have a foothold from which it can expand to other areas or periodically shell regime-controlled parts of Damascus, demonstrating Assad's inability to provide order. Either way, its growth in Syria could well increase as U.S. and Iranian-backed forces in Iraq push the group from the east, and as Washington continues to sidestep a coherent strategy for assisting the opposition in Syria.
Jeffrey White is a defense fellow at The Washington Institute and a former senior defense intelligence officer. Andrew J. Tabler is a senior fellow at the Institute and author of "Syria's Collapse and How Washington Can Stop It" (Foreign Affairs, July-August 2013).