Manbij, which lies near the Syrian border with Turkey, has long been a point of contention between the two powers. In 2016, the United States, together with allied Kurdish forces, made a push to oust the Islamic State from the city. The mission was meant to block the militant group from access to the Turkish border, and it came in preparation for a larger campaign to liberate Raqqa slated for the following year. But the operation violated a long-standing Turkish red line against any Kurdish presence west of the Euphrates River.

Ankara was none too pleased. It viewed the westward march of Kurdish militias as a threat to its national security. And so, just after the fall of Manbij, in the summer of 2016 Turkish troops invaded northern Aleppo. The Turkish operation, dubbed Euphrates Shield, ousted the Islamic State from its last positions along the border. But it also blocked all potential overland routes for the Kurds to push west toward the isolated canton of Afrin, where they would have joined with another contingent of Kurdish forces holed up there. In early 2018, Ankara followed Euphrates Shield with a second operation, dubbed Olive Branch, through which it took full control of Afrin and drove out the Syrian Kurds.

During the buildup for that operation, Turkish President Recep Tayyip Erdogan signaled that Manbij could be next. And in a January speech, he warned U.S. troops not to get too close to the People’s Protection Units (YPG), the most powerful Kurdish militia among those with which the United States works in Syria. The YPG also happens to be connected to the Kurdistan Workers’ Party (PKK), an insurgent group that has been active in Turkey since 1984.

To smooth things over with Turkey, former U.S. Secretary of State Rex Tillerson traveled to Ankara in February to meet with Turkish Foreign Minister Mevlut Cavusoglu. The two agreed to establish two working groups, one on Syria and one on broader issues in the U.S.-Turkish relationship, including the detention of U.S. citizens, the conviction of a Turkish national in New York, and Ankara’s purchase of Russia’s S-400 missile system.

The working groups, which launched soon after Tillerson’s trip, had mixed results. In June, though, the two sides did reach an agreement on Manbij. Together, they crafted a road map to work together, rather than at cross-purposes, in the city. The plan called for independent patrols by each country along the area’s border, which would be followed by integrated military patrols down the line. Now that the joint patrols have started, the road map’s second phase is supposed to kick in. That will involve the United States and Turkey vetting members for the Manbij Military Council, which currently governs the city.

But the Manbij Roadmap has been plagued by a lack of clarity from the start. Ankara has insisted that the agreement was supposed to have a tight timeline. But the United States, for its part, has maintained that both sides were supposed to meet specific conditions before moving from stage to stage. The back-and-forth has undermined the road map’s intended effect: Tensions between the erstwhile allies remain high, and no one is sure what will come next.

Over and over again, Erdogan has made clear that he views Manbij as a stepping stone for clearing all YPG presence from eastern Syria. To underscore the point, Turkey has recently bombarded YPG positions near Manbij and elsewhere along the Syrian-Turkish border with artillery fire. Turkey intends to use the military pressure to accomplish two things: first, to try to convince the United States to drop its Kurdish partners, and second, to force Washington to negotiate Manbij Roadmap-style agreements for other towns in eastern Syria. Implicit is Turkey’s threat that if the United States doesn’t do what Turkey wants, it will continue to rain munitions down on territory that has, for the past several years, been relatively conflict free.

The United States, despite having had ample public warning from the Turkish government, appears to have been caught off guard by the recent uptick in shelling. It is struggling to respond, vacillating between trying to placate Turkey by privately hinting about future concessions along the border and quietly rebuking the Turks and warning that U.S. forces will defend themselves if fired on.

The United States’ top priority is to prevent Turkey from destabilizing northern Syria. The Turkish attacks challenge a central assumption about the direction of the Syrian civil war: that the various front lines have hardened and that the combatants’ existing positions can be used as the basis for negotiations to end the conflict. But the United States doesn’t really have a good option for responding to Turkey—it is not going to drop the Kurds, like Turkey wants, or start bombing Turkey in order to get that country to fall in line.

The United States’ only realistic interim step is to try to fix the Manbij Roadmap in an attempt to take the immediate point of conflict out of the equation. Without another round of talks to flesh out the agreement, the process of vetting new members for the governing council is certain to be fraught, with each side withholding national intelligence about why it deems certain people to be off-limits. If the process breaks down entirely, Ankara will likely only increase the pressure on the Kurds in Syria.

To keep it on track, the United States could exchange Turkish assurances that it will stop its shelling in return for U.S. promises to place restrictions on YPG operations. Such a freeze-for-freeze should be a minimum near-term U.S. goal. That would require trust, of course, which has been lacking. But a good-faith effort to clarify the road map should help.

Turkey, of course, will also want pledges from the United States to pursue talks about governance and security in other towns in northeastern Syria, but the United States doesn’t really have much incentive to agree to that. After all, that part of Syria has been relatively free of violence for years now, and a return of some external forces to these territories could prompt Kurdish-Arab or Kurdish-Turkish clashes. That would undercut efforts to end the Syrian conflict. If the United States wanted to seriously consider expanding the Turkish presence in northeastern Syria, it would have to figure out how to do so while also lowering the temperature on Turkish-Kurdish relations.

Indeed, over the long term, of course, a stable Syria will depend on doing so. Ultimately, the only thing that will prevent a future conflict will be peace talks between Turks and Kurds, but the proper incentives aren’t yet in place for such negotiations. There might not be much the United States can do for now, but, at a minimum, U.S. policymakers need to be clearer with Ankara—and with themselves. Turkey has clear security priorities and will use force to achieve them. Its objectives are irreconcilable with those of the Syrian Kurds and, of course, of the United States. Because of that, Ankara cannot simply be managed with an ill-defined road map and a plan to muddle through, which will only reinforce the strained status quo.

As the United States and Turkey continue their joint patrols, and as the countries begin the difficult process of vetting lists of people they know little about, the lack of detail in the Manbij Roadmap is certain to lead to more tensions. No matter what happens, Turkey will share a border with Syria long after the United States leaves. The Syrian Kurds, too, will maintain their presence in the region. If only to prevent the Islamic State from regaining a foothold in disputed territory, it is in the United States’ interest to get the Turks and Kurds to cooperate, which will require clarity about U.S. intentions and a commitment to tackling the vexing issue of Turkish-Kurdish relations. None of this will be easy. But it is the only way to stop Turkish artillery strikes in eastern Syria and end never-ending speculation about invasion.

Aaron Stein is a resident senior fellow at the Atlantic Council’s Rafik Hariri Center for the Middle East.

Foreign Policy

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