In May-June 2017, US aircraft carried out three attacks against loyalist troops advancing through the Badiya (central desert) towards al-Tanaf, a Syrian-Iraqi border crossing held by Pentagon-backed rebels and Western special forces. It was the first time since the start of the conflict that Washington had provided Syrian insurgents with direct air support against pro-regime forces. This showdown was a paradoxical result of the strategy followed by Russia after its military intervention in Syria in September 2015. To ensure the success of this intervention, Moscow worked towards concluding de-confliction agreements with other state actors involved in the conflict, namely, the United States, Jordan, and Turkey. Yet, precisely because this strategy achieved its main goal, that is, bolstering Assad’s military position in western Syria, it rapidly led to renewed international tensions. As loyalist forces returned to eastern regions in which they had only maintained isolated garrisons after their retreat in 2012, they came into direct contact with rebels operating against the Islamic State (IS) with Turkish support, in the northern Euphrates valley, and backed by the US and Jordan, in the southern Badiya. While in the north, the presence of a quasi-neutral third party – the Kurdish YPG – has constituted a buffer between the two other parties, in the south, the respective expansions of loyalist and rebel forces into formerly IS-held territories has translated into direct confrontation and heightened the risk of escalation between foreign powers.
Loyalist Consolidation in Western Syria
The fall of eastern Aleppo in December 2016 was the coronation of a series of loyalist victories made possible, from October 2015 onwards, by a combination of three main factors. First, the Russian intervention vastly increased the firepower of pro-regime forces through the deployment of several dozen aircraft and the upgrading of the Syrian army’s armoured and artillery components. Second, besides limited Russian intervention on the ground, loyalist manpower has been bolstered by thousands of Shia foreign fighters recruited by the Iranian Pasdaran in Iraq, Lebanon, Afghanistan and Pakistan. Although such forces had started to operate in Syria in late 2012, they were considerably strengthened in late 2015 by the return to Syria of Iraqi militias that had been scrambled back home in the summer of 2014 to fight the IS insurgency, and by the provision of combat vehicles sourced from the militaries of Syria, Iraq, and Iran.
The third factor that paved the way for loyalist success against the rebels was Russia’s ability to secure deconfliction agreements with key sponsors of the rebels. Although the CIA did not end, and even initially increased, its covert support programme for vetted insurgent factions after the Russian intervention, Moscow and Washington nevertheless negotiated the formalization of their cooperation in Syria through the establishment of a Joint Implementation Group (JIG) in the framework of which they would cooperate against IS and the Nusra Front. The agreement was cancelled two days before its planned start in September 2016 due to an allegedly accidental US airstrike against regime soldiers in Deir ez-Zor, but the outgoing democrat administration nevertheless stood firm in its rejection of the last-ditch attempt at changing its Syrian policy and engaging in military confrontation with Assad.
In the south, Russia rapidly succeeded in convincing Jordan to establish a joint coordination centre in Amman and to freeze support for anti-regime operations by the Southern Front rebels, whose sole task would now be to fight the Yarmouk Martyrs Brigade (known as the Khalid bin al-Walid Army since May 2016), an IS affiliate operating in the western part of the province of Der’a. For the Hashemite kingdom, whose chronic sense of vulnerability had been exacerbated since 2011 by the irresolute behaviour of its American protector in the Syrian conflict, cooperating with Moscow was primarily a matter of protecting the country from the spillover effects (in particular a renewed influx of refugees) of a potential escalation by loyalist forces along its border.
The consequences of Jordan’s backtracking were rapidly felt, and had a profound impact on the dynamics of the war in southern Syria. With fewer fronts to fight on, and weaker rebels, loyalist forces struck devastating blows to their enemies. In January 2016, they retook the town of Sheikh Maskin along the Damascus-Der’a highway, then redirected their efforts towards the suburbs of Damascus. In the spring, they captured the southern half of the rebel-held eastern Ghouta, exploiting a deadly turf war between the area’s main rebel factions, the Army of Islam and the Rahman Corps.
Following the August 2016 seizure of the western suburb of Daraya, whose entire remaining population was forcibly displaced, the regime’s strategy undertook a dramatic shift. Whereas since early 2014 local truces had allowed rebels to maintain control over several besieged localities of the Damascene periphery, the regime now stepped up its military effort against those towns and demanded the complete disarmament of their defenders, or their evacuation to the northwestern insurgent stronghold of Idlib. Truces were thus abrogated west of the capital (Ma‘damiyya, Khan al-Shih, Kanakir, and al-Zakiya), north of it (Qudsiyya, al-Hamma, and al-Tell), along the Lebanese border (Barada valley), in Homs’ al-Wa’r neighbourhood, and by May 2017, in the inner Damascene neighbourhoods of Qabun and Berze. In parallel, Islamist factions Ahrar al-Sham and Tahrir al-Sham finalized two-year long Qatar-mediated negotiations with Iran over the simultaneous evacuation of four besieged towns, the opposition-held Madaya and Zabadani, in the Anti-Lebanon Mountains, and the Shia, pro-regime Fu’a and Kefraya, near Idlib. In February-March 2017, suicide attacks by Tahrir al-Sham and the Islamic State in regime-held neighbourhoods of Homs and Damascus were a possible harbinger of forthcoming transformations in the insurgency’s modus operandi if the rebels’ territorial control in the region was to fade away entirely.
Military dynamics in the north unfolded in a similar way after the Russian intervention, even though Turkey was harder, and longer, to convince. Ankara initially calculated that by bolstering its support for the rebels (including, most spectacularly, by shooting down a Russian bomber over the Syrian-Turkish border in November 2015), it could turn Moscow’s intervention into a quagmire. By early 2016, however, two major rebel defeats along the Turkish border signalled that such hopes were unfounded: in January, insurgents were expelled from their strongholds of Rabia and Salma in the coastal mountains, thereby losing most of their positions in the province of Latakia; the following month, a joint offensive by loyalist forces and the Kurdish PYD in the northern countryside of Aleppo cut the rebels’ supply lines between the city and the border crossing of Bab al-Salama. Both campaigns increased Turkey’s already considerable refugee burden, as tens of thousands of civilians flocked to the border to escape Russian bombardments.
The Turkish stance on the Russian intervention further changed afterwards because of Ankara’s decision to launch Operation Euphrates Shield in August 2016. The AKP government had announced its intention to establish a “security zone” in northern Syria one year earlier, following the June 2015 capture of Tell Abyad by the PKK-aligned PYD. This development had allowed the Kurdish party to ensure territorial continuity between its self-administered cantons of Cizire and Kobane, a scenario whose repetition Turkey was determined to prevent by seizing the IS-held positions separating Kobane from the western canton of Afrin. As Ankara was initially held back by US reluctance and the Russian intervention, it hoped it could still fulfil its project by increasing its help (including through cross-border artillery support) for the rebels trying to move east from A’zaz against IS. Not only did these efforts fail, however, but their failure coincided with the US-backed PYD’s capture of the city of Manbij, which Turkey had planned to include in its security zone. The AKP government then engaged in an ambiguous policy aimed at securing Russia’s acceptance of Operation Euphrates Shield while preserving the loyalty of mainstream Syrian rebel factions, which provided Euphrates Shield with auxiliary ground troops. During the siege of eastern Aleppo and final loyalist onslaught on the city in the last weeks of 2016, Turkey refrained from encouraging the rebels to make a last stand, acting instead as a mediator in the negotiation of the evacuation agreement. Afterwards, moreover, Turkey agreed to join Russia and Iran in running the Astana Process, a series of conferences which in May 2017 led to the proclamation of four “de-escalation zones” across western Syria.
Deconfliction, or outright victory, in the south and the north, left loyalist forces with one main stumbling block in western Syria, that is, the large rural area centred on the province of Idlib and stretching from the north of Hama to the western approaches to Aleppo. This insurgent powerhouse dominated by Ahrar al-Sham and Tahrir al-Sham has served as a launch pad for the major rebel offensives that briefly broke the siege of Aleppo, in August 2016, and came dangerously close to the city of Hama, in the summer-autumn of 2016 and the spring of 2017. Although advances made by the rebels during the latter campaign were rapidly reversed, the fear they instilled in the regime was apparently sufficient to spark the decision to deter a further attack by launching the 4 April sarin bombing of Khan Sheikhoun, a city used by the insurgents as a rear base for the northern Hama offensive.
The US decision to respond to the Khan Sheikhoun attack by launching cruise missiles against the regime’s airbase of Shu‘ayrat came as a surprise given previous assumptions that the Trump Administration was exclusively concerned with the anti-IS campaign. However, this unprecedented development did not signal a major shift in Washington’s strategy in Syria, since, in spite of initial ambiguities, the missile strike was strictly defined as a way to deter further use of chemical weapons by Assad. For the regime, the consequences of the US move were negligible from a military point of view, yet they were more serious at the diplomatic level. Before the fall of Aleppo, the regime had started lobbying Western countries, in particular European ones, by highlighting the fact that its increasingly strong military position made it the only credible partner, hence recipient of foreign funding, for the stabilization and reconstruction of the country. Based on implicit blackmailing over further waves of refugees if the regime was not given the economic means to retain its population, this lobbying campaign was met with some success among Western analysts and decision-makers, but it suffered a severe (albeit probably temporary) blow when US Tomahawks reasserted Assad’s status as an international pariah.
During the siege of eastern Aleppo and final loyalist onslaught on the city in the last weeks of 2016, Turkey refrained from encouraging the rebels to make a last stand, acting instead as a mediator in the negotiation of the evacuation agreement
Despite the bombing of Shu‘ayrat, therefore, loyalist dominance made military developments in western Syrian an increasingly inconsequential source of international tensions. However, by allowing pro-regime forces to return to the east, and to challenge foreign powers operating there, the same trend significantly raised the geopolitical significance of the region.
The Northeastern Front: Entrapping Turkey
Following the Russian intervention, regime forces started to slowly move eastwards from Aleppo into IS-held territories. The first major push towards Raqqa was met with a disastrous setback in June 2016, but the capture of eastern Aleppo in December, and ensuing proclamation of a nationwide cessation of hostilities, allowed loyalist troops to resume operations in the area and, after four years of absence, to reach the Euphrates river by March 2017. The move was primarily aimed at stopping the advance of the Euphrates Shield forces which, after the capture of al-Bab, announced their intention to push south to take part in the liberation of Raqqa from IS. Turkey argued that in spite of their multi-ethnic character, the US-backed Syrian Democratic Forces were unfit to retake Arab-majority Raqqa due to their submission to PYD leadership. Now trapped in their northern pocket, Turkish troops tried to force their way to Raqqa through the PYD-held city of Manbij, yet rapidly had to cease their advance due to the deployment of regime, Russian, and US units in the area.
Regime-PYD cooperation entailed benefits for both partners: the regime could reopen a land connection between Damascus and the northeastern Jezireh, and the PYD did the same between its western and eastern possessions. This cooperation does not necessarily preclude future confrontation, however, the PYD’s project of “democratic federalism” being fundamentally at odds with Damascus’ pretensions to reassert its control over a centralized Syria. Moreover, the Kurdish party’s relations with Assad’s Iranian ally have grown tense over the spring of 2017 due to the progress made by Tehran-backed Popular Mobilization Units on the Iraqi side of the border, which has allowed them to challenge the PKK’s influence in the Iraqi region of Sinjar, as well as to attack IS-held Syrian villages claimed by the PYD in the south of the province of Hassake.
The ambiguity of the PYD’s position has allowed Russia to play a complex balancing act by exploiting Turkish military pressure (for now limited to sporadic bombings of Kurdish positions) to foster collaboration between the regime and the YPG, while at the same time using the threat of increased support for the Kurdish militia to shape Ankara’s policies in its favour. By sending troops to the western YPG stronghold of Afrin in March 2017, Moscow deterred Turkish attacks against the area while emboldening YPG leaders, who evoked the possibility of moving south to the province of Idlib and seizing the border area from the rebels. Securing Russia’s restraint in its support for the PYD has been one of the main reasons for Turkish participation in the Astana Process. As part of the latter, Ankara paid lip-service to the idea of joining Russian and US efforts against Tahrir al-Sham, which in turn led to a significant increase in armed incidents between rebel groups: Tahrir al-Sham branded Turkish-backed factions as part of the “Astana conspiracy,” hence as legitimate targets in its attempt at seizing strategic positions across the northwest and ensuring its long-term survival in a hostile international context.
Although the PYD’s multiple allegiances have made northern Syria a remarkably complex strategic environment, the Kurdish party’s ambiguity has also allowed it to play the role of buffer, hence to mitigate international tensions for the time being. In the Badiya, however, the absence of such a third-party in the regions abandoned by IS have put the regime and the US-backed rebels on a collision course.
The Race to Deir Ez-Zor
Loyalist campaigns in the central desert (Badiya) are the best illustration of the regime camp’s instrumental approach to ceasefire agreements, whose purpose is not to pave the way for a negotiated settlement, but to allow for the reallocation of manpower to the east. The nationwide cessation of hostilities proclaimed in February 2016 allowed loyalist forces to retake Palmyra from IS, one year after the city fell to the Jihadi group. Palmyra was lost to IS once again in December 2016 as loyalist forces were concentrated in Aleppo, but a new cessation of hostilities at the end of that month paved the way for a new successful counterattack, following which regime forces expanded their control in the central desert. The Russian-Iranian-Turkish agreement on de-escalation zones announced in May 2017 was once again used by the regime to prepare for a large-scale offensive aimed, this time, at re-opening the road from Palmyra to the besieged garrison of Deir Ez-Zor, and further south, to reassert control over the Syrian-Iraqi border.
The string of victories won by loyalist forces in western Syria throughout 2016 allowed the regime and its allies to redirect their attention against a retreating IS, hence to cooperate with, or confront, local forces that had been fighting the jihadi group in relative isolation from the civil war’s western theatre
Besides the ambition to retake the oil-rich Syrian-Iraqi border area, the desert campaign was primarily motivated by the aim of foiling a parallel offensive carried out against IS by Jordan-backed rebel units operating alongside members of US, British and Norwegian special forces. In late 2015, the Pentagon started to train and equip a “New Syrian Army” (NSA) made up of rebels previously expelled from Deir ez-Zor by IS. In the following March, the NSA took the border crossing al-Tanf, at the meeting point of the Syrian, Jordanian and Iraqi borders, and in June, it carried out a bold, but disastrous, attack behind IS lines on the military base of al-Hamdan near Al-Bukamal. As IS weakened in the spring of 2017, however, the NSA (refashioned as Jaysh Maghawir al-Thawra) and other US/Jordanian-backed units that had long been operating in the southeastern part of the central desert (Jaysh Usud al-Sharqiyya, the Martyr Ahmad al-‘Abdo Forces) seized large parts of the southern desert, reaching the administrative limits of the province of Deir ez-Zor in May. Accusing the US, the UK and Jordan of preparing a large-scale ground operation towards Al-Bukamal, pro-regime forces spearheaded by Iran-led Iraqi and Afghan Shia militias attacked US-backed rebels on the ground, and bombed one of their bases along the Jordanian border. Loyalist advances towards al-Tanf were met with the May-June US airstrikes, but the regime camp reacted by circumventing the al-Tanf garrison and pushing towards the Iraqi border further north, thereby linking up with pro-Iranian Iraqi militias operating on the other side of the border.
The arrival of loyalist forces on the Syrian-Iraqi borders marked a major strategic turning point in the conflict, not only because it hindered further progress by US-backed towards Al Bukamal, but also because it allowed the Pasdaran to establish a land bridge between Iran, Iraq, Syria, and Lebanon. By mid-June 2017, Washington’s only reaction to this development was a purely defensive one, as HIMARS multiple-rocket launchers were deployed to al-Tanf to deter further loyalist attacks. The US thus seemed unwilling to accept it had been checkmated by the Islamic Republic, but it was also unlikely to engage in a significant military escalation against pro-regime forces, which, given the limited manpower of the al-Tanf rebel units, would require a significant increase in US boots on the ground. The Trump Administration was thus most likely to adopt a wait-and-see policy by keeping a zone of influence that would provide it with a strategic asset in a possible confrontation with Iran in the post-IS era.
The string of victories won by loyalist forces in western Syria throughout 2016 allowed the regime and its allies to redirect their attention against a retreating IS, hence to cooperate with, or confront, local forces that had been fighting the Jihadi group in relative isolation from the civil war’s western theatre. Loyalist expansion to the east did not only reconnect previously separate battlefields, but also increased the risk of direct confrontation between the regime camp, on the one hand, and Turkey, the US and Jordan, on the other hand, even though the latter countries had gradually distanced themselves from the conflict’s master cleavage since the Russian intervention. The destabilizing effect of IS’ 2014 blitzkrieg in Iraq and Syria might thus be felt long after the Jihadi organization ceases to control any territory: the threat from IS provoked, or facilitated, the direct intervention of foreign powers (the US, Iran, Russia, and Turkey) between which IS initially acted as a buffer, but that are now increasingly facing each other as the “Caliphate” dwindles. Paradoxically, therefore, the end of IS could actually make the Syrian conflict more volatile than ever.
 “51 U.S. diplomats urge strikes against Assad in Syria,” New York Times, 16 June 2016.
 “Jordan’s balancing act in Syria,” The New Arab, 1 November 2015.
 “Syria forces quietly take up buffer between Kurds, Turks,” Daily Mail, 7 March 2017.
 Matthew Barber, “The end of the PKK in Sinjar?,” Syria Comment, 30 May 2017; “Rojava security forces discuss defence system against ‘Iranian project’ in a meeting in Syria’s Qamishli,” ARA News, 30 May 2017.
 “Îlham Ehmed: Russia is threatening Kurds with Turkey,” ANF News, 31 May 2017.
 “Is Turkey rattled by the Russian-Kurdish deal?,” Almonitor, 24 March 2017.
 “The Jordanian Proxy – Plans of Aggression in South Syria Will Not Triumph,” Al-Watan (Damascus), 26 April 2017.