A US-Iran Race to Control the Damascus-Baghdad Highway

The Syrian war has recently taken a new and decisive turn. The military focus has shifted from the country’s western areas to the long-neglected east, and this might now decide the Levant’s predominant hegemon. Across these territories held by the Islamic State in Iraq and the Levant (ISIL) since 2014, American- and Iranian-backed armed groups are scrambling to capture or defend territories with one target in mind: controlling the strategic Damascus-Baghdad highway. The unprecedented US strike on May 18 that hit Iranian-backed militias approaching the al-Tanf military base did not prevent the Syrian regime from advancing toward that critical converging point on the Syrian, Iraqi, and Jordanian borders. The battle for that strategic highway could be the ultimate test for President Donald Trump Administration’s proclaimed agenda of deterring Iran’s regional activities.

The significance of the al-Tanf crossing

In May 2015, ISIL captured the last border crossing between Syria and Iraq. Within days, government security forces simultaneously withdrew from the neighboring border cities of al-Tanf (southeastern Syria) and al-Waleed (southwestern Iraq) in what was then a pivotal moment that allowed ISIL to take over half of the Syrian territories. ISIL fully controlled and eliminated that physical border between Syria and Iraq, which allowed the terrorist group to swiftly expand territorial gains.

“Highway 1,” which runs through Iraq, links the Gulf countries with the Levant via Baghdad. The 1,200-kilometer road begins in Umm Qasr (Basra Province) and passes through al-Nasiriyah, al-Diwaniyah, al-Hilla, Baghdad, Fallujah, and Ramadi before reaching Ratba (Anbar Province), where it splits into two highways: north to al-Waleed crossing (still under ISIL control) that goes to Syria, and south to Taribil crossing that goes to Jordan. On the Syrian side, Highway 1 becomes the “M2 Damascus-Baghdad Highway,” which goes through Qalamoun, a strategic area that links Lebanon to Syria.

For Iran, that strategic highway is consequential to restoring the main supply line from Iran via Iraq to Syria and Lebanon. The United States seeks to cut that supply line and build instead a military base flanked by friendly Sunni and Kurdish forces. By controlling the Damascus-Baghdad road, rebels seek to fully break the Syrian regime’s siege in the eastern part of Qalamoun, while the Syrian regime aims to deny rebels the ability to disrupt its supply line and to secure the countryside of Damascus.

The military focus shift to the east was precipitated by three significant developments in recent weeks: 1) the Astana talks ceasefire allowed the Syrian regime and the Iranian-backed militias to reconsider priorities and shift manpower from Idlib in Syria’s northwest to Deir Ez-Zor in the east; 2) the weakening of ISIL and its rapid withdrawal from large areas on both the Iraqi and Syrian sides left everyone scrambling to capture vacant territories; and 3) the advancement of the Iraqi forces against ISIL and the potential spillover of ISIL militants made controlling the Syrian side of the border a priority.

The ground game to secure the Damascus-Baghdad Highway

Syrian opposition groups, based in the al-Tanf camp, comprise the Revolutionary Commando Army (previously known as the New Syrian Army, backed by the United States), Forces of Martyr Ahmad al-Abdo, Lions of the East, and the Army of Free Tribes (backed by Jordan). In March 2016, these groups captured the al-Tanf crossing and struggled initially to protect the base from ISIL attacks, which led to tensions among members of the alliance as well as doubts regarding the US commitment to support them. In December 2016, the New Syrian Army fighters, who were expelled in August 2016 from the Saudi-backed Authenticity and Development Front, regrouped and formed the Revolutionary Commando Army. Since then, the US-led coalition has been gradually expanding influence by investing in a Sunni force that would lead the ground battle against ISIL in Deir Ez-Zor.

The US-led coalition and the Free Syrian Army are working on three fronts: 1) the Revolutionary Commando Army is advancing to capture the al-Bukamal crossing with Iraq as a platform to expand control in Deir Ez-Zor; 2) the Jordanian-backed Army of Free Tribes is advancing from southern Syria and on May 30, launched the “desert volcano” military campaign to “oust Iranian and other foreign militias working alongside regime forces in the Syrian desert”; and 3) Syrian rebels are pushing pro-Syrian regime forces and Iranian-backed militias away from the Zarqa checkpoint located around 56 kilometers from al-Tanf.

The Pentagon remains mute about whether it will shift away from backing Syrian rebels against ISIL to supporting them against the Syrian regime and the Iranian-backed militias. However, there are indications that it might gradually move in that direction. Syrian rebels announced on May 30 that they are receiving support from the United States, Jordan, and Saudi Arabia in their efforts to prevent Iran from opening a supply route between Syria and Iraq. In recent weeks, the rebels have reportedly received armored vehicles and TOW missiles. That limited support will obviously not alter the balance of power on the ground but might be enough for the rebels to stand their ground.

Under President Barack Obama’s Administration, US forces stayed away from any confrontation with both Syrian regime forces and Iranian-backed militias. While Defense Secretary Jim Mattis noted that the May 18 strike does not mean “we are increasing our role in the Syrian civil war,” he also remarked that “we will defend ourselves if people take aggressive steps against us.” US forces dropped fliers on May 29 warning pro-Syrian regime forces and militias to return to the Zaza checkpoint; however, hundreds of these troops remain close to the al-Tanf training site with a smaller number actually inside the deconfliction zone.

Meanwhile, on May 9 the Syrian regime began a military campaign in the east to seize control of Deir Ez-Zor. As a preamble to that military shift, the Syrian regime claimed that the United States and Jordan are preparing a ground invasion from the southern border, which the Pentagon swiftly denied. However, beyond securing the countryside of Damascus, the Syrian regime’s movement toward the al-Tanf crossing is mostly returning the favor to Tehran by ensuring its access to the Levant. The pro-Syrian regime alliance is advancing on three fronts: 1) from the countryside of Damascus by opening a parallel road toward the al-Tanf crossing; 2) from the Syrian desert in the eastern countryside of Palmyra in Homs Province toward the strategic city of al-Sakhna; and 3) from Athriya in Hama Province toward Deir Ez-Zor.

The Iranian-backed groups helping the Syrian regime are most notably the Iraqi-based Kataeb Sayyid al-Shuhada (KSS, an Iraqi militia with ties to the Iranian-backed Badr Organization) and the Lebanese based Hezbollah. The US strike on May 18 hit a convoy led by KSS, which issued a statement (AR) noting, “a strike on our presence in Syria is a strike on our presence in Iraq, and we will hit the enemy and his supporters everywhere.” Hezbollah has reportedly deployed 3,000 forces in the al-Tanf region to participate in the regime’s operations in the Syrian desert, known as al-Badiyah. These forces have been active in Qalamoun and have dismantled checkpoints on the Lebanese-Syrian border to free up forces.

What is happening on the Iraqi side of the border cannot be isolated from developments in Syria. On May 18, Iraqi Prime Minister Haider al-Abadi sent his envoy, national security advisor and head of the Popular Mobilization Forces (PMF) Faleh al-Fayyad, to Damascus to discuss the need to coordinate the fight against ISIL and efforts to control the shared border. While the Iraqi army remains in a stalemate in the Mosul battle, on May 12 the PMF began an offensive from the north to the south along the border with Syria. That route carries less risk with no confrontation expected with the Syrian Kurdish Forces in al-Hasaka in northeastern Syria; it also allows the PMF to cut ISIL’s supply line and prevent its militants from crossing into Syria. After advancing north and controlling Umm Jrays on Highway 47, which links Mosul to the southern countryside of al-Hasaka, Iraqi government forces will be set to meet PMF militants in al-Qa’em on Iraq’s border, where the Iraqi forces are expected to take over operations to prevent clashes with US forces on the Syrian side of the border.

The race for Deir Ez-Zor

The pro-Syrian regime forces and allied militias are attempting to encircle the al-Tanf crossing to reach the Iraqi border, which would accomplish two simultaneous objectives: cut the Free Syrian Army road to capture Deir Ez-Zor and ensure an alternative supply line with Iraq. Indeed, Iran reportedly changed the course of its land corridor between Iraq and Syria to avoid a confrontation with US forces. The new carved corridor is 140 miles south of the US military base; it goes through al-Mayadeen and Deir Ez-Zor to avoid the Kurdish northeast before crossing into Tel Afar and Mosul.

So far, there are no indications the pro-Syrian regime forces and militias will cross the red line to approach the triangular area that links Jordan, Iraq, and Syria; however, the real battle now is the race between US- and Iran-backed groups to control Deir Ez-Zor, which has been named the “Berlin” of the Syrian conflict. Deir Ez-Zor lies at the intersection of two armed groups backed by the United States. On the one hand, Kurdish-led Syrian Democratic Forces (SDF) are advancing from the northwest via Raqqa; on the other hand, the Free Syrian Army is advancing from the southwest. Last March, the SDF cut the road that links the countryside of Raqqa and Deir Ez-Zor.

Dividing influence in Deir Ez-Zor seems inescapable. Yet, the question is whether that delineation will be part of a US-Russia understanding or end up being one of Syria’s most consequential battles. By controlling Deir Ez-Zor, Washington hopes to turn it into a Sunni buffer zone adjacent to northern Kurdish areas and the Iraqi border. However, it is unclear whether the US approach is only linked to defeating ISIL or if it is part of a long-term plan to sustain influence in Syria. Some media reports (AR) are hinting that the Pentagon is now ready to include the Southern Front, an alliance under the supervision of the US-led Military Operations Center based in Amman, in that battle. Winning control of eastern Syria will turn what once was considered an impoverished area to a strategic prize from which to project influence across the eastern Mediterranean. Whether the Syrian regime cut the Syrian rebels’ road to Deir Ez-Zor or the other way around, the celebration will not last for long. The emerging winner will lead the ultimate battle against ISIL with a rival faction in the back.

Calculus of the US, Iran, and Russia

For the first time in the six years of the Syrian war, the United States seems to be on a collision course with Iran. While both the Syrian rebels and the Iranian-backed militias are eager for a showdown, Washington and Tehran remain cautious for several reasons:

  • US options are limited. Beyond its overwhelming air power, the Pentagon’s ground game is poor in eastern Syria with nearly 1,000 Special Forces and a complex relationship with the Free Syrian Army. The US’s main ally, the Syrian Democratic Forces, has an indirect agreement with the Syrian regime and is unwilling to engage in a battle with the Iranian-backed militias. Restrained by the investigation surrounding Russian interference in the US elections, the Trump Administration’s hands are tied in terms of its ability to make a grand deal with Moscow on Syria. Furthermore, Washington’s relationship with Ankara is strained for multiple reasons, most notably because of the US arming of Syrian Kurds, which has left US forces acting as a buffer between Turkish forces and the Kurdish People’s Protection Units (YPG). US policy in Iraq largely depends on P.M. Haider al-Abadi staying in power, though at any given time, Iranian pressure could hamper, if not doom, his ability to govern.
  • Iran can only go so far. Without Russian airpower, Iranian-backed militias have a tremendous handicap in approaching US forces. Tehran cannot afford losing its partnership with Moscow while its relationship with Ankara remains difficult. The Iranian-backed militias are already stretched thin; moving Hezbollah to the east means less troops to fight ISIL and al-Nusra along the Lebanese-Syrian border. Nothing was more helpful for Iranian-backed militias than US neutrality in the Syrian civil war; therefore, direct US involvement might be a game changer that could roll back some of Iran’s gains in Syria.
  • Where Russia stands. Russian Foreign Minister Sergei Lavrov said Moscow was not informed about the May 18 strike and described the American use of force in al-Tanf as “very alarming.” Russia will not risk providing air support for the Iranian move toward al-Tanf, not only because it does not seek a confrontation with the United States but also because it needs Washington’s endorsement of the “de-escalation zone.” If the Astana talks fail, the potential of confrontation will increase. The only way to prevent an open war in eastern Syria is to sustain the US-Russian open communications channel. On the other hand, Moscow is not leaving anything to chance. On May 31, its cruise missiles hit ISIL positions near Palmyra in the southeast, thus again making Russia’s role pivotal in the battle against the group and in the eventual outcome of the competition for the Iraqi-Syrian border.

It is not clear to what extent Syria and Iran are in conflict or working in tandem when it comes to eastern Syria. Obviously, Moscow is in a compromise mode since the Astana talks, while Iran is focused on the priority of securing a supply line between Syria and Iraq. The United States is ready to accept a Russian role if Iran stays away from southern Syria; however, the possibility of a disagreement between Moscow and Tehran might be elusive. So far, US and Russian airpower has been restrained, allowing both the Syrian regime and opposition to lead the ground battle. However, a gradual escalation could lead to a subtle cold war on Syrian soil between the two major powers. Washington has the option now to either help Syrian rebels race toward Deir Ez-Zor or push back against the Syrian regime and its allies. If Iranian militias move in to targets in the vicinity of al-Tanf, that will likely provoke the United States to become further entangled in the war. The Syrian regime has the military edge but has a lot of areas to cover, while the Syrian rebels have the quicker route to capture the al-Bukamal crossing and move into Deir Ez-Zor.

What matters for the United States at this stage is to control Iraq’s Highway 1, which splits into Jordan and Syria. A US security company already has received the contract to secure the road to Jordan despite criticism from the PMF, and Sunni tribal units took over the Ratba district behind the Taribil border crossing to calm US and Jordanian concerns. Now the Trump Administration is attempting to secure the Baghdad-Damascus road. The question is whether the United States is ready to share influence with Iran in pushing to establish a supply line from al-Mayadeen to Tel Afar, or if it will seek full control of the Iraqi-Syrian border.

The upcoming summer in the Syrian desert will make the terrain extremely difficult to navigate; areas in Deir Ez-Zor and al-Baaj (Iraq) will be harder to capture, leaving US and Iraqi forces with a sole option: to rely on airpower. While ISIL is retreating, it still has the strength to resist and might exploit the divisions among the rival factions. If the United States and Iran opt to end their tacit understanding in fighting ISIL, that would have repercussions from Iraq to Lebanon. The Trump Administration’s Syria policy will be tested in the coming weeks; it will have to decide whether defending the Damascus-Baghdad highway is worth direct US involvement in the Syrian war.

Joe Macaron is a Resident Analyst at Arab Center Washington DC. To learn more about Joe and read his previous publications click here