Photo: Turkish military vehicles drive towards the northern Syrian town of al-Bab, Syria March 7, 2017. REUTERS/Khalil Ashawi

The trajectory of the Syrian conflict has changed considerably in recent weeks. The United States, working by, with, and through local ground forces is poised to begin the assault on Raqqa, the Islamic State’s most important urban area in Syria.US-Turkish relations now hinge along a 50 km (31 mile) front line, snaking east to west along the Sajur river, and down to a smattering of small villages south of the town of Arimah. Various forces are now in control of intersecting front lines, including: Syrian Kurdish, Kurdish allied Arab forces, American Special Forces, Syrian regime elements, Russian Special Forces, Iranian units, Turkish military units, and Turkish allied forces. These groups—many of them hostile with one another and engaged in battle elsewhere in Syria—are now within mortar range. The events that led to the current state of affairs began years ago, but the implications of the recent moves in Syria could signal a potential settling of conflict lines, perhaps resulting in a de-facto outcome for iterative talks between the various warring parties, first to de-escalate along front lines, and then for a broader peace arrangement.

Manbij: A Failed US-Turkish Effort

In November 2014, former Vice President Joe Biden reached a tentative agreement with then Turkish Prime Minister Ahmet Davutoglu to cooperate in Syria. For much of that year, the United States and Turkey were locked in negotiations about Incirlik Air Force Base in Adana, Turkey for strike missions and an airbase in Diyarbakir for Combat Search and Rescue (CSAR). The two sides remained at odds over how best to pursue shared goals: using military force to defeat the Islamic State (ISIS, ISIL, or Daesh), while simultaneously providing arms and training to elements of the Arab dominated opposition to force Bashar al-Assad to make political concessions.

For Turkey, Incirlik was a key source of leverage with the United States. The base is 113 km (70 miles) from the Syrian border, which would allow coalition pilots to remain on station for longer and to ease the burden placed on US tanker assets that assist pilots flying from airbases in the Persian Gulf. Turkey, as a condition for opening the base, demanded that the United States establish a no-fly-zone over northern Syria, extending as far as Aleppo. For the United States, the threat of ISIS superseded that posed by the regime. The negotiations were inconclusive.

Meanwhile, east of the Euphrates, American airpower (flying from outside of Turkey) continued to give support to the Syrian Kurdish People’s Protection Units (YPG), a militia linked to the Kurdistan Workers’ Party (PKK). The PKK has waged an insurgency inside of Turkey for more than three decades, first for Kurdish independence, and then for political autonomy. The YPG’s advance, in turn, prompted Turkey to re-evaluate its demands with the United States, in favor of joint action west of the Euphrates. Ankara sought to limit Kurdish expansions west of the river to block the YPG from consolidating control over a strip of territory along Turkey’s longest land border.

In late July 2015, the Turkish government opened Incirlik to coalition aircraft to armed intelligence, surveillance, reconnaissance (ISR) missions. The first strike from an armed MQ-1B took place in early August, outside of Tel Abyad, and in support of advancing YPG. Shortly thereafter, American aircraft began strike missions. The Turkish government, in turn, began discussions to clear the Manbij pocket with Arab and Turkmen forces, based in towns stretching from Azaz to Marea. These negotiations resulted in three interrelated agreements: 1) The United States, with Turkish support, would expand its training program to include the rebels then based in northern Aleppo; 2) Turkish aircraft would patrol this area, which, along with artillery moved to the border, would support this group’s operations against ISIS; 3) The US would deploy Special Operations Forces to Kurdish held territory and began the training of Arab forces, dubbed the Syrian Arab Coalition (SAC).

The Pentagon, however, lacked the legal authority to operate in these areas, prompting the passage of H.R. 3979, which included the Title 1209 authorities governing American military support to the Syrian opposition. The authorities bar the United States from directly arming the YPG (without a Presidential waiver), but allow for the provision of weapons to the SAC—which fights with the YPG as part of the Syrian Democratic Forces (SDF).

The Train and Equip (T&E) program was intended to close the Manbij pocket without violating Turkey’s stated redline: No YPG presence west of the Euphrates. For Ankara, the YPG’s presence east of the river was, without question, viewed with suspicion, but was less threatening than a contiguous Kurdish presence along the border. The T&E program was intended to train smaller units to help guide US air strikes, a seemingly minor task, but important for how the United States conducts air operations by, with, and through local actors, within circumscribed rules of engagement. The media coverage focused on two incidents: when Syria’s al-Qaeda affiliate, then known as the Nusra Front, attacked T&E forces near Azaz, and how one US-trained leader handed his weapons over to Nusra to buy protection. These incidents, while regretful, undermined political support for the program, leaving no viable alternative to close the Manbij pocket (other than the SDF).

The Turkish downing of a Russian Su-24, and subsequent Russian bombing in support of the YPG north of Aleppo city in February 2016, nearly wiped out the rebels fighting along the Marea line—upending the T&E program. In response, the program was scaled back. However, its successes should not be overlooked: Two T&E groups, Liwa al-Muatism and the Hamza Brigade, are now fighting as part of Euphrates Shield, alongside a smattering of other groups that continue to receive US support. However, the program failed to achieve its objective: to close the Manbij pocket without SDF forces, despite significant US support to the rebel groups, including 50 percent of strikes and ISR sorties from Incirlik. The failing prompted the use of the SDF west of the Euphrates, an operation that had initial Turkish acceptance, despite the YPG presence within the SDF. The initial push to the city began in April 2016 and ended on August 12, after a month long siege.

Twelve days later, on August 24, 2016 Turkish armor and Special Forces, trailed by various rebel groups, moved across the border into Jarablus. The timing of the operation does not appear to have been coincidental—it coincided with Vice President Biden’s visit to Ankara to express support for Turkey, following the failed July coup attempt. Days later, Turkish forces moved into al-Rai, starting a march to ISIS-held al-Bab. In the opening days of operation Euphrates Shield, the United States and Turkey reached an agreement, whereby US forces would deploy 20 km (12.5 miles) into Syria to support the offensive. At the start of operation Euphrates Shield, Turkish forces clashed with the SDF south of Jarablus, before the United States helped to broker a ceasefire to help quell clashes along SDF territory west of Manbij and along the Sajur River. The Turkish invasion, it appears, was in response to the consolidation of the SDF presence in Manbij and the likelihood that the group would soon push out, through al-Bab, to link up the YPG held Efrin canton in northwest Syria. This operation would have resulted in SDF control over the Turkish border, an untenable outcome for Turkish security officials.

The Raqqa Link: Why Manbij Matters

Euphrates Shield, therefore, was the logical—if reactive—Turkish response to the failure of T&E and other efforts to use Arab and Turkmen forces to close the Manbij pocket. However, Ankara’s military intervention has now run afoul of US and Russian interests in Syria. For the United States, the focus is still on taking Raqqa, using SDF forces and an increased US military footprint to break Islamic State defenses around the town and to push deeper into the Euphrates River Valley. It also explains why Ankara, from the outset of Euphrates Shield, telegraphed its intent to consolidate in al-Bab, and then ousted the SDF’s Manbij Military Council, a civilian entity comprised of Arabs, but tied to the Syrian Kurdish Democratic Union Party (the PYD, which is the political arm of the YPG). For the United States, a Turkish move on Manbij would risk YPG forces pulling back from the front lines in Raqqa to protect Manbij, leaving the front lines with ISIS under-defended.

Earlier this March, the Manbij Military Council, working through Russia and the Syrian regime, seemingly brokered a deal to allow for Syrian regime and Russian elements to enter towns west of Manbij. The agreement remains murky, with credible claims that the SDF simply changed uniforms to those worn by the regime-allied NDF militia. Russia’s quiescence to this arrangement, regardless of what the current situation on the ground, is instructive. The perceived Russian support for regime elements embedded with the SDF has created a de-facto buffer zone that, for now, has dissuaded Turkey from giving direct military support to the various militias clashing with YPG elements along the zone’s periphery. Absent direct Turkish support, the Euphrates Shield militias cannot take significant territory from the YPG/regime element.

The idea of a buffer zone is in Russia’s interests, despite on-going efforts to cultivate closer ties with Turkey. Russia, too, has an incentive for Raqqa to fall. Moscow is supporting the regime’s offensive south of al-Bab, which appears intended to move towards Maskana, a town 40 kilometers (25 miles) south of the regime’s current front line position. From Maskana, the regime will probably push further south along the Euphrates towards al-Thawra, the town on the southern bank of the Euphrates, opposite the Tabqa Dam. On a second axis, the regime, with Russian air support, will likely push from Palmayra to Deir Ezzor, where ISIS has besieged a Syrian regime airbase since July 2014. Moreover, in accepting the return of regime soldiers to Manbij, the Syria Arab Army managed to carve out a presence in territory lost early in the war without firing a shot.

The Next Phase: The Euphrates River Options

The Russian-Regime forces have, in the past, failed to advance on multiple axes, including from Palmyra. The Russian military has proved to be effective in using mass bombing to achieve tactical objectives, but less adept at fighting an air war on multiple fronts, where ISR and precision bombing is required to fend off ISIS assaults. Still, presuming the regime can consolidate control over at least one of these two axes, the end result will be multiple points of contact with the SDF along the Euphrates. Turkey, in this scenario, is still confined in Euphrates Shied territory in north Aleppo, where it must now begin to build up governing institutions to consolidate control over territory it now occupies. This will not be an easy task, with competing groups under de-facto Turkish control espousing vastly different visions for the future construct of civil institutions, like civilian courts, police forces, and basic civic institutions. Turkey is engaged in this effort already, reportedly training a contingent of forces from the area near the border to move into north Aleppo, either as police forces or to join Arab units fighting on different fronts.

The current Turkish policy points to an inherent contradiction in near term military and political goals. The establishment of civil institutions, independent of the central government (presumably with Assad or a trusted adviser taking control of post-conflict Syria) strengthens the case for a decentralized Syrian state, which will also strengthen the case for some semblance of Kurdish self-rule north and east of the Euphrates. Moreover, should the United States decide to leave behind a small contingent of Special Operators to conduct high value strikes against ISIS targets in Syria, the de-facto reality will be to de-escalate along regime-Kurdish contact points, creating the way towards negotiations around lines on a map. The same is true if the US military pushes the US State Department to help with stabilization (an outcome that, at the moment, would be problematic because of the Democratic Union Party, or PYD). This scenario bodes poorly for US-Turkish relations, in that Turkey will see the United States as having created a Kurdish entity in eastern Syria. Russia, too, will be blamed. However, for the vast majority of Turkish policy makers, Russia is not treated as an ally, and therefore its “betrayal” is to be expected. The United States, on the other hand, is Turkey’s most important ally, despite the tensions now dominating the relationship—making the “betrayal” far more impactful.

The Syrian conflict appears to have entered a new phase, with the regime moving south of al-Bab, and the start of the SDF push in and around Raqqa. The trajectory of the war is at odds with Turkish interests, despite the tactical successes Ankara achieved with Euphrates Shield. The United States could seek to provide additional guarantees to Turkey about the future of the Syrian state and the PYD’s place inside of it, but this issue is certain to dominate American-Turkish relations for the foreseeable future. Turkey, in contrast, should be expected to remain intransigent about the Syrian Kurdish issue, holding out the option to attack SDF position in Manbij or Tel Abyad, both of which could slow a future Raqqa campaign, one would logically presume will start in the next few months. The Syrian conflict remains bloody, with war crimes committed on a routine basis. However, the regime’s moves and concurrent actions in Raqqa and, potentially, the Euphrates River Valley, are creating territorial facts on the ground – and therefore challenging elements for US diplomats and policymakers that must continue to walk a fine line between Turkey and the Syrian Kurds, a non-state actor. The conflict will continue, but the realities that could define future peace talks are being created through the use of force. This trajectory is now detrimental to Ankara’s interests, ensuring continued US-Turkish tensions.

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