What holds the Syrian Democratic Forces (SDF) together? This is an important question, as Washington has thrown its support behind this coalition of politically disparate factions in the fight against ISIL. Indeed, the SDF reportedly now controls 60 percent of Raqqa — the collapsing caliphate’s self-proclaimed capital — in addition to most of northeast Syria.

SDF promotional material tells the story of a multi-ethnic band that strives together towards decentralized, participatory government, which would protect the rights of all ethnic groups without emphasizing their distinct identities. While it does count large numbers of Arabs among its ranks, the SDF is dominated by Kurds affiliated with the Democratic Union Party (PYD), itself an offshoot of the Kurdistan Worker’s Party (PKK). Even more than a shared vision for governance, or hatred of the self-proclaimed Islamic State, it is obedience to PYD authority that sits at the core of the coalition.

A look at the SDF’s history reveals that Kurdish leadership has taken a scattershot approach to Arab participation, accepting, and subsequently marginalizing, a succession of rebel and loyalist outfits — in addition to fo­rcibly conscripting Arab youth. The common thread linking these actions is an insistence on netting Arab soldiers while maintaining PYD control over the coalition and the territory it captures. This strategy has precluded the formation of strong bonds between the SDF’s Arab auxiliaries and Kurdish core, ensuring that power dynamics and mutual interest keep them whole. Participating enables Arabs to fight a winning battle against ISIL alongside northeast Syria’s dominant, American-backed force, and possibly reap benefits in a PYD-led political system. Failure to buy in can mean a group’s demise.

The PYD has its reasons for monopolizing power within the SDF, including the fact that its armed wing, the People’s Protection Units (YPG), is a disciplined and motivated force, as opposed to many of its Arab partners. And as long as the PYD remains the strongest player in northeast Syria, able to incentivize or force participation, the coalition is likely to hold together.

The problem is that the PYD’s dominance is not guaranteed to last. Washington has sent conflicting signals about whether it will continue its military and political support to its Kurdish partners after ISIL is sufficiently degraded. Such support has so far protected them from possible Turkish and regime attacks. If the PYD’s supremacy is compromised by a withdrawal of American backing, or by any number of future scenarios, the party might face defections and infighting among the SDF’s estimated 23,000 Arab fighters — some of whom have been alienated by overbearing leadership, and others who were loyal to other factions from the beginning.

Rebel Defections

Since its predecessor coalition began operations against ISIL in 2014, the SDF has adopted revolutionary language, and recruited Arab-majority rebel groups. Both the PYD and certain rebel brigades have a common enemy in ISIL, and both were in a position to receive U.S. support after previous efforts to back moderate opposition units failed. On an ideological level, the term “revolution” has resonance for the PYD’s two main domestic audiences: Kurds sympathetic to the revolution in Rojava (western Kurdistan) and residents of Arab-majority areas. These residents tend to be wary of the PYD because of its supposed separatist designs and relationship with the regime. So the SDF uses anti-Assad branding in order to gain parts of the Arab opposition’s trust.

But the PYD’s rigid authority over the coalition has led to repeated waves of rebel defections. First, two groups broke off and announced their hostility to the YPG after it took control of the border town of Tal Abyad in June 2015 and joined it to the PYD’s political project. Kurdish leadership had promised to hand over administration of the ethnically-mixed town to rebels when it was captured from ISIL, according to a participating brigade’s spokesman. But Tal Abyad proved too lucrative a prize to give up, because it is crucial to creating a band of contiguous Kurdish-held territory across northern Syria.

Another participating Arab rebel outfit disbanded six months later. The Tribes’ Army was gaining local support in Tal Abyad and issued a strongly worded denouncement of Kurdish forces’ alleged human rights abuses against Arab civilians there. These actions challenged YPG superiority and prompted a crackdown. Finally, when Turkey launched Operation Euphrates Shield, a joint Turkish and rebel advance into northern Syria in summer 2016, an Arab SDF commander fled to rebel-Turkish territory with his fighters. In a subsequent interview he complained that the YPG had kept supplies and weapons from its Arab counterparts and denied them the chance to rule territory as ISIL was pushed out (accusations echoed by other commanders).

Today, the SDF’s historically largest rebel participant has been sidelined from the battle for Raqqa City and its leadership is under YPG-enforced village arrest. Other longtime partner brigades have been riven by internal splits over fighting alongside the YPG. A stream of rebel defections continues.

New Arab self-proclaimed rebel groups have joined the SDF over the past year. With the revolution effectively over on the military stage, these outfits appear to be more committed to fighting ISIL and reaping whatever material or political gain can be found through alignment with the PYD. Like their predecessors, they are subject to the strict control of the PYD, which has forced one brigade to withdraw repeatedly from the Raqqa front after trying to position itself as a partner rather than subordinate.

The balance of power in northeast Syria has left few alternatives for local rebels other than falling in line behind Kurdish SDF leadership. The only other resident powers they could align themselves with are the Syrian regime and ISIL, which controls a shrinking slice of territory. Seeking greater autonomy within the SDF is likely to provoke an unwinnable fight with the YPG, and defecting to the Turkish-rebel region to the west is a dangerous option, because the YPG has pursued defectors as a security threat.

On the other hand, fighting for the SDF enables rebels to defeat a longtime enemy, ISIL, and in some cases to free their hometowns from ISIL rule — all while Washington protects them from regime and Russian airstrikes. This course also offers the prospect of some power in a post-ISIL, PYD-run government. For example, the political wing of one rebel brigade was reportedly allotted several seats on the future Raqqa City Council, which is set to rule that city after its capture. The same brigade’s leader appears to be using participation in the SDF as a way to bolster his credentials on the international stage, to ensure he can play a role in a future peace settlement.

Still, the balance of power could change quickly. If the United States reduces or ends its assistance in the post-ISIL phase, and the PYD comes under serious external threat, the coalition is full of fighters whose main reason for joining will have vanished — and some of whom have a bitter history with their Kurdish partners.

Mandatory Service

The PYD has forced thousands of Arab (and Kurdish) youth to serve in the SDF and its associated military entities. This strategy has stirred resentment among northern Syria’s residents, and could backfire in the long run if the party loses its grip on power.

Young men in the PYD’s three cantons are conscripted into “Self-Defense Forces,” and local militias by other names in Arab-majority areas farther south. On paper, these forces are separate from the SDF, but in reality they share the same leadership (e.g., see the career path of commanders Shurfan Darwish and now-deceased Adnan Abu Ajmed), and sometimes wear the same uniform and participate in the same operations, so for our purposes the distinction is nominal.

Arab individuals join the SDF by choice, to be sure. Some sign up for the salary, while others are convinced by the coalition’s ideology. But the rate of enlistment among Arabs appears to have fallen concurrent with the PYD’s alienation of rebel brigades in northern Syria, and reports of human rights abuses against Arab residents. So PYD-affiliated security forces have resorted to regular month-long arrest campaigns to net new soldiers. Youth can hide at home or try to flee abroad to avoid service, but stories of Arabs killed while resisting conscription are increasingly common.

Among other reasons, recruits object to service because PYD leadership controls the SDF and its self-defense forces. A Kurdish journalist who regularly meets with Manbij civil and military leaders, and requested anonymity, told us over messaging app that in Manbij, “the thing that upsets residents is that 80 or 90 percent of internal security are from all ethnicities…but the final decision lies with Kurdish leadership.”

In the best of cases, these conscripts would drop their weapons and return to civilian life after their term of service ends. Or they could work as “police forces, or border guards,” an option for SDF personnel in the post-ISIL phase, spokesman Haj Mansour told us over the phone. But if a credible challenge to PYD rule appears in the future, SDF leadership might come to regret the thousands of Arab men whom the coalition has armed and trained, but whose loyalty it has compromised through heavy-handed conscription.

Dual Allegiances

The SDF has also accepted pro-regime loyalists to boost Arab enlistment over the past two and a half years. As long as these groups do not proclaim their allegiance to Damascus too loudly, their presence in the coalition is tolerated. This strategy has helped solve short-term recruitment problems, but gives the regime a future advantage in dealing with the PYD at the negotiating table or on the battlefield.

“There are Ba’athist leaders and rank and file in the SDF” Ivan Hasib, an al-Hasakah based journalist, told us over messaging app. In al-Hasakah Province, over 100 fighters with the loyalist National Defense Forces defected and joined the SDF in summer 2016 “because the YPG arrested most of them, and besieged the village of al-Diba” where they were from, said al-Hasib.

Perhaps the most high-profile loyalist brigade in the SDF is Liwa Suqur al-Raqqa, whose commanders were secretly recorded last year discussing logistics with regime officials, and who sent a representative to meet with Ba’ath Party national leadership in Qamishli. A short-lived affiliate group openly announced its allegiance to Assad and the head of his intelligence services, prompting a crackdown by another SDF outfit.

If the PYD and regime are to negotiate control over northeast Syria, Assad can push for a more favorable deal because his soldiers constitute a portion of his rival’s security forces. The regime already provides phone service and civil records, maintains parts of the electricity and water grids, and pays public sector employees’ salaries in PYD areas. Having fighters in the SDF is another card Damascus can play to show the international community, and supporters, that it remains the legitimate authority in these territories.

A more worrying scenario emerges in the event of an open regime-PYD confrontation. Currently this is unlikely because the latter has demonstrated its military superiority in previous rounds of fighting. In addition, Russia pressures both parties to strike a deal, and the new U.S. administration has attacked loyalist forces that threaten its SDF partners.

However, Assad stated that he intends to retake all of Syria, and regime officials have consistently threatened the PYD’s project. These threats could turn serious if the regime concentrates its troops near Kurdish areas once ISIL and holdout rebels are mostly defeated. If widespread clashes break out, in the event the United States withdraws its support or due to other unforeseen events, the SDF contains loyalist soldiers who could pass along intelligence and potentially act as a fifth column.

Tribal Bonds

The presence of tribal groups in the SDF illustrates the extent to which Arab loyalty to the coalition originates with the PYD’s authority.

The SDF has prioritized outreach to northern Syria’s Arab tribes, in recognition of how important their support is both for the military alliance, and the political project it brings with it. One of the PYD’s staunchest allies in the SDF is a tribal militia loyal to Hamaydi Daham al-Jarba of the Shammar tribe, who has historically sided with Syrian Kurds against regime efforts to quash their national rights.

But tribal support is complicated and fluid. Rarely does a single leader command the allegiance of any given tribe, e.g., even the Shammar, with its pro-PYD bent, has minority camps oriented towards the opposition and regime. In addition, northern Syria’s tribes are opportunistic and non-ideological actors, with tribal leaders shifting alliances multiple times over the course of the war to secure the best deal for themselves and their communities. Hamaydi Daham al-Jarbah dreams of cementing his power along the Iraqi border through his relationship with the PYD, and already profits off an oil trading agreement with them.

“In this area, people obey the ruling power,” al-Jarbah said in a 2015 interview.

It is an open question whether the SDF will succeed in gaining Arab tribal support in remaining ISIL-held areas. Even if it does, continued tribal backing after ISIL will depend on the PYD’s ability to dole out benefits and suppress dissent. This dynamic raises troubling questions about the extent of tribal loyalty to the PYD, in the event it falls from its northeastern Syrian throne.

We do not intend to present a doom-and-gloom perspective here. It is undeniable that the SDF has proven successful in its anti-ISIL mission, and enjoys popular support in some areas because it brings order, relative economic prosperity, and personal freedoms after stifling ISIL governance.

But the PYD’s approach to Arab participation — accepting and coercing groups of divergent political orientations, and conscripting youth — means that the party’s authority, and resulting mutual interests, form the glue that holds the SDF’s disparate components together. Ideally, Washington would keep this point front and center as it plans for the post-ISIL phase, in order to avoid the worst-case scenario of defections or infighting among the alliances’ Arab groups.

Dan Wilkofsky is a Syria Analyst at the Navanti Group LLC, a commercial research company focused on development and stabilization issues. Dan is a former editor at Syria Direct. He’s on Twitter as @Dwilkofsky1.

Khalid Fatah is a Voice of America (VOA – Kurdish service) TV and radio reporter, and a Kurdish-Middle East analyst at the Navanti Group. Previously, Khalid wrote for the newspaper al-Itehad and Khabour magazine, where he focused on Iraqi Kurdish issues.

Image: U.S. Army photo by Sgt. Mitchell Ryan