The United States is treading a narrow line in southeastern Syria, attempting to counter Iranian expansion without exacerbating the conflict or further embroiling American troops. A recent push by Iranian-backed groups toward a base used by U.S. advisors is elevating the prospects of direct conflict between the United States and Iran. While U.S. forces could easily rout Iran’s allies, this approach is far too risky. Instead, Washington should leverage its support for Moscow’s diplomatic efforts by demanding the addition of the Al-Tanf area of southeastern Syria to the safe zones in the Russia-brokered de-escalation plan.
Sitting at the crossroads of Syria and Iraq, Al-Tanf connects the central highway that runs from Baghdad to Damascus. ISIS captured the city from the Assad regime in 2015, and, in turn, U.S.-backed Syrian opposition forces captured it in March 2016. Since then, the area has been of strategic and tactical value to the U.S. and its partners. U.S. advisors have used Al-Tanf as a base of operations to train and support opposition forces fighting ISIS in the eastern Euphrates valley. Holding this area has enabled the U.S.-led coalition to halt the movement of supplies and ISIS personnel into the Syrian desert, and it will be crucial for future operations against ISIS in Deir ez-Zor and Abu Kamal in the lower Euphrates valley. Moreover, the U.S. and FSA presence in the Al-Tanf area has prevented ISIS offensives on the Al-Rukban IDP border camp, which houses nearly 80,000 displaced Syrians. Keeping ISIS and Iranian-backed forces out of this area will be essential for protecting this vulnerable population.
In early May, Assad-aligned militias led by the Iranian Revolutionary Guard Corps launched offensives to capture territory held by U.S.-backed Free Syrian Army (FSA) groups in southeastern Syria. Their advances brought them closer and closer to U.S. forces operating in around the Syria-Iraqi border crossing of Al-Tanf, and ultimately into a 55-kilometer buffer zone that the United States agreed upon with Russia. On May 18, after the Iranian-backed militias ignored warning shots, U.S. forces struck one of their convoys to force them to retreat, reportedly killing eight fighters.
In the days that followed, militias loyal to Assad took further territory in a second front extending from As-Suwayda. Fighting between FSA groups and Iranian-backed militias has continued, and the United States has increased its “presence and footprint” in and around Al-Tanf to further deter Iran. In early June, both regime and opposition sources claimed the United States set up a new base of operations northeast of Al-Tanf, and on June 5, an FSA group reportedly shot down a Syrian air force jet, killing the pilot. With these developments, the risk of wider clashes and deterioration in southeastern Syria remains high.
Iran’s push for al-Tanf serves two of its objectives. First, capturing the crossing would bring the entire Baghdad-Damascus highway under the control of Iranian-backed groups, allowing Iran to dramatically increase its access to and support for the Assad regime, over which it and Russia are quietly competing for influence. Connecting this highway would also give Tehran unprecedented access to Beirut and the Mediterranean. That being said, it is highly unlikely Iranian-backed forces will take Al-Tanf at this stage. Doing so would require them to fire on U.S. forces—something unprecedented in the Syrian civil war.
As Iranian-backed militias continue to clash with U.S.-backed opposition groups, Iran accomplishes its second and more realistic objective: testing Washington. Failure to adequately defend and support the opposition against Iran will damage U.S. efforts to use these forces against ISIS.
While many in Washington would be more than happy to engage in direct conflict with Iran in southern Syria, this would likely drag the United States into direct conflict with the Assad regime. It could also lead Iranian-backed militias in Iraq, including the Popular Mobilization Forces and Kata’eb Hezbollah, to target U.S. forces. Bottom line: it would vastly complicate U.S. efforts against ISIS in both Syria and Iraq.
But U.S. leaders have another option for dealing with encroaching Iranian-backed forces. If it plays Russia right, the United States has a real opportunity to counter Iran diplomatically in Syria.
On May 4, Turkey and Iran agreed to a Russian de-escalation plan for Syria. According to the proposal, Russia, Iran, and Turkey would act as “guarantors,” enforcing ceasefires over major opposition-held territory in Idlib province, northern Homs countryside, Eastern Ghouta, and part of southwestern Syria—effectively forming four safe zones. Talks on the details of the plan have continued among the three guarantors, but Russia is keen on winning wider international buy-in for its efforts.
As Russia tries to gain wider support for its initiative, it is particularly eager to involve the United States. On May 30, Russian Prime Minister Sergey Lavrov indicated that Moscow “welcomes U.S. participation” and suggested the United States should “join the efforts to coordinate the parameters of the de-escalation zones.” With this, Washington has considerable leverage and can condition its acceptance of the plan on the inclusion of Al-Tanf and southeastern Syria—where Russia does not have significant interests—as a fifth safe zone. This would allow the U.S.-led coalition to continue operations against ISIS from the south, stop Iran from connecting the Baghdad-Damascus highway, and prevent clashes that could disrupt the ceasefires elsewhere in the country. The United States should also push for itself and Jordan to be included as guarantors of the ceasefires in the south where Turkey has little if any influence.
With U.S. support on the horizon, Russia may be willing to take steps to rein in Iran. Whether Moscow has this leverage remains to be seen—indeed, Iran will oppose the inclusion of southeastern Syria as a fifth safe zone—but Iran also does not want to be seen as a spoiler to Russia’s diplomatic efforts. Iran, without a valid reason to convince Russia to oppose the inclusion of the Al-Tanf area as a safe zone, may well fold.
For now, the Iranian-backed groups seem to have halted their advance toward Al-Tanf, but their clashes with the FSA continue, and it is only a matter of time until they butt heads with U.S. forces again. As Iran and its militias test the United States, Washington must respond carefully. It must balance opposing Iranian influence and expansion in southern Syria with avoiding escalation that risks further complicating U.S. operations in both Syria and Iraq. By tying Al-Tanf and southeastern Syria into Russia’s diplomatic efforts, the United States can put the onus on Moscow to restrain Iran, and it can bring Syria closer to lasting ceasefires and, eventually, a solution. The diplomatic route requires more patience, but it is far more responsible and will be far more durable if it succeeds.