The Iranian-Syrian alliance stretches back to the creation of the Islamic Republic of Iran in 1979, constituting one of the most enduring partnerships among authoritarian regimes in the region. Since 1979, Iran and Syria have remained close allies despite fundamental differences in their governments: Iran is a Persian theocracy, and Syria is an Arab secular state. Their partnership grew out of shared enmity toward Saddam Hussein’s Baathist regime in Iraq, U.S. regional dominance, and Israel.

In the 1980’s, Syria supported Iran throughout the brutal Iran-Iraq War. President Hafez al Assad, Syria’s president at the time, was the Islamic Republic’s only ally in the region. The rest of the Arab states either sided with Saddam, who was invading the newly-formed Islamic Republic, or remained neutral, fearing that Iran would foment Shi’a revolutions within their borders, as it had been trying to do in Iraq.

Throughout its history, the Islamic Republic has viewed its partnership with Syria as a vital national security interest. When popular uprisings against Bashar al-Assad’s regime broke out in March 2011 amid the “Arab Spring” and turned into a civil war that threatened to unseat Assad, the Islamic Republic of Iran, with the support of its proxies, invested massive resources into saving and sustaining its partner. With the help of Iranian troops, Iran-backed militias, and Russian air support, Assad has regained control of most of the country. However, the U.S. military remains present in the east and northeast of the country.

Iran’s partnership with Syria is central to its strategy to dominate the region. Assad allows Iran to set up military bases across the country and conduct military and proxy operations against Israeli and U.S. interests. He also provides the Iranians with access to critical transit routes through Syria. Sometimes referred to as a “land bridge,” these roads connect Iran to the Mediterranean Sea, allowing it to supply Hezbollah—its proxy in Lebanon—with increasingly sophisticated weapons, including precision-guided missiles (PGMs), that are a direct threat to the Israeli homeland. The Syrian Civil War provided Iran with an opportunity to secure its logistics network, which it also uses to distribute arms to its proxies and pro-government forces within Syria.

By supporting Assad, the Iranian regime also denied a victory to its regional Sunni rivals, and further consolidated its “Shi’a Crescent,” stretching from the Persian Gulf to the Mediterranean. Regional Sunni powers, along with the U.S., were supporting Sunni rebels fighting against Assad. Jaysh al-Islam was one of those rebel groups supported by Saudi Arabia. Iran’s Sunni rivals saw an opportunity not only to deprive Iran of a key ally, but to support the rise of Sunni political influence in the country. While in the interest of Sunni powers, including Qatar and Turkey, who helped Saudi Arabia back rebels against Assad, Iran saw this as a direct threat to its influence in the Levant. Assad’s continuation in power provides a check against Sunni power in Syria and the greater Middle East.

Throughout his term of in office, former Iranian President Hassan Rouhani articulated, on multiple occasions, that the purpose of Iran’s intervention in Syria was the defense of the Assad regime. Speaking with Syrian Prime Minister Wael al-Halqi in August 2013, Rouhani vowed, “the Islamic Republic of Iran aims to strengthen its relations with Syria and will stand by it in facing all challenges. The deep, strategic and historic relations between the people of Syria and Iran… will not be shaken by any force in the world.” In December 2020, Rouhani reaffirmed Iran’s support for the Assad regime, declaring, “The Islamic Republic of Iran will continue its support to the Syrian government and people as our strategic ally and we will stand by Syria until its final victory.” He added Iran will continue fighting in Syria until the Golan Heights are liberated from Zionist occupiers. Given that the supreme leader and the IRGC’s Quds Force run point on the Syria file, Iran’s policies towards the Assad regime have remained unchanged since the elevation of Rouhani’s successor, Ebrahim Raisi, as president in 2021.

While the policies remain unchanged, President Raisi’s role in Syria-Iran relations is different from his predecessor’s. For example, President Raisi attended a meeting between Iran’s supreme leader and President Assad, when the latter made a surprise visit to Tehran in May 2022. He joined Quds Force commander Esmail Qaani and members of the Office of the Supreme Leader. Former President Rouhani did not attend when President Assad met the supreme leader in February 2019. Furthermore, President Raisi’s foreign minister, Hossein Amir-Abdollahian, was invited to attend, unlike former President Rouhani’s foreign minister, Javad Zarif. Javad Zarif resigned, because he was cut out of the loop, but the supreme leader rejected his resignation.

President Raisi’s attendance at the meeting suggests that the supreme leader wishes to position him as the leader of an anti-American, anti-Israel informal military alliance, known as the “Axis of Resistance,” that includes Iran, Syria, Palestinian terror organizations, and Hezbollah. The meeting also signals Tehran’s interest in ensuring that Syria stays a member of this axis, and does not drift toward the Gulf Arab states, such as the United Arab Emirates (UAE), a signatory to the Abraham Accords. Only two months prior to the meeting, President Assad traveled to the UAE.

Iranian Economic Support to the Assad Regime

In support of the Syrian regime's campaign of mass murder to suppress the popular unrest, Iran has conducted an extensive, expensive, and integrated effort to keep Syrian President Bashar al-Assad in power. In the early stages of the conflict, Iran offered limited assistance to the Assad regime in the form of technical and financial support, facilitated primarily through the IRGC’s Quds Force. Beginning in 2012, Iran's economic support increased markedly to forestall the collapse of the Assad regime.

It is unknown exactly how much Iran has spent to prop up the Assad regime, but estimates range from $30 billion to $105 billion in total military and economic aid since the onset of the conflict. In 2017, Iran, through its state-run Export Development Bank, extended Syria an additional $1 billion credit line, adding to the $5.6 billion total credit lifeline Iran provided the Assad regime in 2013 and 2015 to keep the Syrian economy afloat and facilitate Syrian purchases of petroleum. Iran’s provision of credit to the Assad regime underscores its increased reliance on Iran for its survival.

Tehran has also greatly expanded its economic ties with Damascus during the Civil War, boosting bilateral trade from a peak of $545 million per year before the war to over $1 billion annually by 2017. Trade volume appears to have dipped since then according to Iranian state media reports, but in 2019, an Iranian official stated Iran’s intention to boost trade volume by an additional $500 million to $1 billion annually within two years. To that end, Iran and Syria held a series of bilateral visits and economic delegations in 2019 aimed at cementing stronger economic ties. Most notably, in January 2019, Iran’s vice president traveled to Damascus and inked agreements solidifying banking cooperation, for Iran to boost Syria’s power generation, and for Iran to restore railways and other infrastructure, all with an eye toward boosting trade. In November 2019, Iran and Syria announced a memorandum of understanding to establish three joint state-owned companies that will focus on reconstructing infrastructure and residential properties.

Iran has used its own oil tankers to transport Syria's embargoed crude oil, disguise its origins, and get it to market. Iran stepped up its provision of diesel fuel to the Syrian regime during the Civil War, fueling the Syrian Army’s heavy ground vehicles – including tanks, infantry fighting vehicles, and heavy transport. Tehran has done so through direct shipments as well as by providing Assad with credit lines to purchase the fuel. Additionally, Iran has provided Syria diesel in exchange for gasoline, a boon of hundreds of millions of dollars to the cash-strapped Syrian government.

Reports by Syrian government media indicate that in October 2018, Iran, hit hard by the re-imposition of U.S. sanctions, suspended its credit line to the Assad regime, triggering a fuel crisis. For at least a period of six months, Iran was unable to export fuel to Syria, but in May 2019, an Iranian oil tanker successfully delivered a shipment of oil, easing the crisis.

Iran’s efforts to provide oil to fuel Syria’s war machine have been ongoing, as evidenced by the July 2019 interdiction by British Royal Marines of an Iranian oil tanker off the coast of Gibraltar carrying 2 million barrels of oil suspected of being destined for Syria. The British operation highlighted Iran’s efforts to maintain its lifeline to the Assad regime in violation of EU and other international sanctions.

As the civil war began to wind down, Iran turned to secure its economic influence in the country. In September 2017, Iran’s Research Institute of Petroleum, a governmental research institute affiliated with the National Iranian Oil Company (NIOC), announced that Iran is planning to build an oil refinery in Syria’s western city of Homs once the civil war ends as part of a consortium involving Iranian, Syrian, and Venezuelan companies. The consortium has already begun pursuing international investments for the project, which will take an estimated $1 billion to construct and will have a projected refining capacity of 140,000 barrels per day.

The Homs oil refinery is one of a series of business deals Iran announced that indicate that the Islamic Republic is poised to take a leading role in the rebuilding of Syria, after playing a pivotal role in the nation’s destruction. Also, in September 2017, Iran signed a series of lucrative agreements to restore Syria’s power grid, and in January 2017, the Iranian government and Islamic Revolutionary Guard Corps (IRGC)-affiliated entities inked major mining and telecommunications agreements with Damascus. The telecommunications agreements are particularly alarming, as they may provide Iran with communications-monitoring and intelligence-gathering tools.

In the process of shoring up its economic interests in Syria to recoup some of the resources it invested in defending Assad, Iran competed with Russia. In 2018, a top Iranian military official demanded oil, gas, and phosphate contracts, seemingly concerned that the Iranians would not receive a fair share of Syrian assets relative to their economic and military commitment to Assad. Russian companies were pursuing contracts in the same industries, and landed more deals than the Iranians.

Iranian Military Support to the Assad Regime

Iranian military support to the Assad regime was at first limited to advising and training regime forces and pro-Assad militias. However, Iran’s support increased markedly in 2012 as Assad risked losing power due to rebel advances and force attrition. Iran began sending hundreds of Islamic Revolutionary Guard Corps (IRGC) and Basij fighters to Damascus, stanching and eventually reversing Assad’s losses. Tehran subsequently greatly expanded its support to include deploying thousands of IRGCArtesh, and Basij fighters to take a direct part in the Syrian Civil War’s battles. These deployments corresponded with Iran taking an increasingly central role in the planning and conduct of the war and marked a departure from Iran’s post-Iran-Iraq War dependence on non-state actors.

Iran has engaged in the facilitation of arms transfers to the Assad regime and proxy militia forces in Syria, including Hezbollah, in violation of U.N. Security Council Resolution 2231, which endorsed the 2015 Joint Comprehensive Plan of Action (JCPOA) and required Security Council approval for Iranian transfers of any weaponry outside Iran. Resolution 2231 expired in October 2020, thus removing the U.N. legal framework used to hold Iran responsible for such arms transfers. These arms transfers have helped Assad regain lost territory and have given Iran and its proxies the ability to project power in the Levant militarily, threatening Israel, Jordan, and other U.S. allies and interests in the region.   

Iran has sent Syria vast quantities of military equipment throughout the civil war, including rifles, machine guns, ammunition, mortar shells, and other arms, as well as military communications equipment. These arms transfers began prior to the introduction of Resolution 2231 and continued after it was adopted—much to the chagrin of JCPOA supporters, who thought that the deal would normalize Iran’s relations with the West and promote cooperation. This wishful thinking proved to be incorrect. The arms transfers continue to this day.

Israel referred Iran to the U.N. Security Council on two separate occasions for alleged violations of Resolution 2231 in Syria, once for launching an “Iranian unmanned aerial vehicle (UAV),” described as having been launched into Israeli airspace to attack Israeli territory, and once for Iran’s delivery of a Khordad air defense system (which Israel destroyed before it could be set up) to an Iranian air base.

Most of Iran's arms shipments into Syria are supplied via air transport. From January 2016 to August 2017, over 1,000 flights, many of them commercial airlines, departed from points in Iran and landed in Syria, indicating an ongoing complex logistical operation to resupply the Assad regime. Air transport remains an alternative to ground and sea transport, but it is vulnerable to airspace restrictions and no-fly zones. Prior to 2011, Iran depended on Turkey’s airspace to transport weapons and personnel; however, at the beginning of the Syrian Civil War, Turkey denied Iran access to its airspace. In March 2011, Turkish authorities interdicted a shipment of machine guns, ammunition, assault rifles, and mortar shells destined for Syria, the U.N. Security Council reported. After U.S. troops withdrew from Iraq in 2011, Iran began to utilize Iraqi airspace for its operations.

In a testament to Iran’s influence in Iraq, in 2012, Obama administration officials failed to convince then Iraqi Prime Minister Nouri al Maliki to close down its airspace to Iranian flights. Then-Iraqi Minister of Transport, Hadi al Amiri, had close ties with Iran, as he previously led a powerful Iran-backed militia, known as the Badr Brigade. Subsequently, the Obama administration mulled enforcing a no-fly zone, but Obama decided against it, fearing that it would draw the U.S. further into the conflict. Building a friendly relationship with Iraqi political leaders opposed to Iranian meddling in Iraqi politics is key to countering Iran’s efforts to dominate the region.

As the tide of the war has shifted in Assad’s favor, Iran has moved to establish a permanent military presence in Syria, effectively transforming the country into a forward operating base from which to threaten and occasionally attack Israel. Iran has set about constructing military bases and weapons production and storage facilities to that end. Israel has targeted Iranian weapons depots on numerous occasions, vowing to strike against Iranian military entrenchment in Syria when it feels threatened. One prominent node for Iranian entrenchment is the T4 airbase, where Iran has sought to establish “a large air force compound under its exclusive control,” according to Haaretz military correspondent Amos Harel. Iran shares the large base with Russian and Syrian forces, but operates independently of them, controlling T4’s western and northern sides.

Highlighting the Iranian danger, in February 2018, Iran launched an armed drone from Syrian territory into Israel, an attack that Israel ultimately repelled. In August 2019, Israel struck Quds Force and Iran-backed Shi’a militia targets in Damascus who were preparing to launch explosives-laden “killer drones” into Israel’s north. Iran’s use of Syria as a staging ground for UCAV attacks against Israel illustrates the extent to which Iran has a free hand to operate in Syria, as Assad has allowed Iran to undertake such operations even though they put his own forces at risk.

In September 2019, Western intelligence sources alleged, and satellite imagery confirmed, that Iran’s Quds Force is constructing a military complex, the Imam Ali compound, not far from the Abu Kamal / Al Qaim border crossing with Iraq, where it will house thousands of troops. Some of the buildings at the compound appear to be heavily fortified, heightening suspicions that they may be used to store sophisticated weaponry, including precision-guided missiles. The compound was partially destroyed by airstrikes after its existence was exposed, but in November 2019, Fox News confirmed that construction of the base is ongoing. In December 2019, Fox News reported that Iran is building an underground tunnel at the Imam Ali complex to store missiles and other advanced weaponry. Western officials claimed Israel destroyed segments of the underground tunnel system in January 2021 amid an accelerating air campaign against Iranian military assets in Syria.

Besides its use for logistical operations, the Imam Ali compound is also used by the IRGC-QF for training grounds. Satellite imagery shows that the combat facilities include: “a 100-meter firing range; a second 100-meter open range that could be used for rocket launcher, improvised explosives and other weapons training; a driver training course; an obstacle course; and a combat course consisting of a dispersed collection of small walls, miscellaneous objects and likely small vehicles used to train troops for combat in urban areas.”

While most of Iran’s military hardware and personnel are concentrated in Syria’s north, Israel is increasingly concerned about the transfer of sophisticated weaponry and precision-guided missiles to Hezbollah forces in the country. To that end, Iran has begun to export its military industry to Syria—another dimension of its military entrenchment—in an effort to counter Israel’s ability to gather intelligence and target weapons transfers. It has set up missile and weapons production capabilities at underground sites in Syria that can be difficult to detect and destroy. These activities may be less vulnerable than land transport to Israeli airstrikes. In some cases, only “bunker-busting” bombs are capable of penetrating the underground fortifications.  

The Saudi news agency Al-Hadath reported in April 2022 that Hezbollah and the IRGC had begun to develop ballistic missiles, chemical weapons, and UAVs under the “Project 99” program at a facility 25 meters below ground and fortified with a thick layer of concrete and steel in the city Masyaf, Syria. “Project 99” appears to be an extension of a cooperative program between Iran and North Korea to develop Scud missiles, which, according to the Wisconsin Project, are capable of delivering chemical weapons. The production of precision-guided missiles is particularly concerning to Israel.

In April 2022, Israel struck in the vicinity of the alleged weapons development site, and Al-Hadath reported at the time that it was targeting a precision-guided missile factory. In Taqsis, Syria, and also in Hama province, Quds Force operatives have taken over an old Syrian regime research facility that is outfitted with tunnels and underground weapons depots. There, they have reportedly begun work on advanced surface-to-surface missiles and chemical weapons. In the Mahin area in the southeastern countryside of Homs, Hezbollah, under the supervision of the IRGC, has set up fortified workshops for the purpose of manufacturing artillery and missile shells, mines and drones, reported the Syrian Observatory for Human Rights in April 2022. The human rights organization noted that its source pointed out that these depots “are considered the second largest arms depots in Syria.”

In addition to focusing on weapons proliferation, Israel is focused on deterring Iranian efforts to establish a presence in the Golan Heights, overlooking Israel’s northern border. In November 2019, an Israeli military official announced, "there are Iranian Quds forces in the Golan Heights and that's not fear-mongering, they're there," increasing the urgency of the IRGC Quds Force threat at Israel’s border.

In July 2020, Iran and Syria signed a comprehensive agreement to enhance their cooperation in the military and defense spheres. Both sides indicated that the agreement was meant to resist U.S. attempts to pressure and isolate Iran and Syria. Iran noted that as part of the agreement, it will “strengthen Syria’s air defense systems within the framework of strengthening military cooperation between the two countries.” Israeli media reported in August 2020 that Israel has carried out over 1,000 airstrikes in Syria since 2017, largely in service of its effort to prevent Iranian military entrenchment in Syria and weapons transfers to Hezbollah. During that period, Israel reportedly took out over one-third of Syria’s air to ensure its continued aerial freedom of operation.

Throughout 2021, Israel expanded its attacks on Iranian arms and missile factories installed in Syria. The Iranians have reportedly sought to use Russian presence as cover for their weapons proliferation and shipment, thinking that the Israelis would hesitate to strike near Russians. Nevertheless, Israel recently attacked these sites, and Moscow did not condemn the attacks. Diplomatic and political sources claim that this indicated Moscow’s “growing impatience with Iran’s involvement in Syria.” According to another expert at CSIS, “Moscow has remained wary about the excessive influence of Iranian-backed militias and non-state actors in a post-war Syria.”

The Russian war against Ukraine has led to increasing military diplomacybetween Iran and Syria. In February 2022, Syria’s head of the National Security Directorate visited Tehran and met with Iranian President Ebrahim Raisi. A month later, Iranian Foreign Minister Hossein Amir-Abdollahian arrived in Damascus to coordinate a “joint position” on the war in Ukraine. The war in Ukraine could allow Iran to expand its influence in Syria as Russia focuses on Ukraine.

Iran’s pledges to bolster Syria’s air defenses and increase military cooperation with Damascus show that it remains committed to entrenching itself militarily in Syria. As Iran has entrenched itself, it has used Syria as a weapons transshipment hub, establishing supply lines to provide drones, precision-bombs, and other advanced weaponry to Hezbollah and Iran-backed Shi’a militias. Israel has repeatedly shown that it is willing to strike Iranian targets in Syria to stanch the Iranian proliferation threat and rein in the arms supply network Iran is building in the region. As such, Syria is likely to remain a battleground for direct Israeli-Iranian confrontation for the foreseeable future.

U.S. troops in Syria are also in danger of Iran-sponsored terrorism. According to the Washington Post, which came into possession of leaked intelligence files from communications intercepts between Syrian and Lebanese militias allied with Iran, Iran has begun planning to escalate attacks against U.S. military convoys in Syria by way of the deadly, remote-triggered roadside bombs known as explosively formed penetrators (EFPs). Iran and Russia agreed in late 2022 to establish a jointly-run operations command center in Syria to coordinate the EFP campaign, according to the leaked intelligence files. Both countries have long sought to evict the U.S. military to allow Assad to reassert control over the entire country, including in the autonomous northeast region, where the U.S.-backed, primarily-Kurdish Syrian Democratic Forces (SDF) are in control,

Provision of Proxies

Iran has deployed an estimated 20-30,000 regional proxies from the Middle East, Afghanistan, and Pakistan into the country. Former IRGC Quds Force commander Qassem Soleimani was the head of these forces until he died in a U.S. drone strike on January 3, 2020, coordinating activities among the various Shi’a mercenary forces and ensuring they fulfilled Iranian foreign policy objectives. General Petraeus, former director of the CIA, described Soleimani as “a combination of CIA director, JSOC [Joint Special Operations Command] commander and regional envoy with the blood of well over 600 U.S. and Coalition soldiers on his hands, and the blood of countless others as well, in Iraq, Syria, Lebanon, Yemen and Afghanistan—in each of which he supported, funded, trained, equipped and often directed powerful Shiite militias.”

These duties have now shifted to Soleimani’s successor, Esmail Qaani. Tehran’s command and control over its proxy forces in Syria has likely suffered since the transition, as Qaani does not have the stature of Soleimani or benefit of close relationships with the heads of various militias that made Soleimani so effective. In June 2020, Qaani reportedly visited the Syrian side of the Abu Kamal border crossing with Iraq, where he vowed that Iran would continue to fight the “Zionist regime” and the U.S. Qaani’s visit was meant to show that, like Soleimani, he is capable of clandestinely visiting Iranian proxies around the region to assert his control over and consolidate unity among the various factions Soleimani previously commanded.

In a testament to the tenuous state of the proxy militia command structure, a number of militiamen from IRGC-affiliated militias were killed fighting among themselves over a dispute regarding the sale of narcotics near Sayyida Zainab shrine, an area controlled by the IRGC and Syrian regime forces, where drug trading by IRGC-backed militias is prevalent. The militiamen reportedly share their profits with their commanders, which probably include IRGC operatives. In this instance of internecine violence, one of the groups had reportedly sold drugs on another’s territory. Clashes even occasionally occur between Hezbollah and the Syrian Army’s 4th Division—both of which are deeply involved in the drug trade in Syria—over how to distribute profits from the drug sales. Conflict is frequently reported in the Deir Ezzor region as well, with an armed altercation between the pro-regime National Defense Forces militia, and members of the Fatemiyoun division, serving as a recent example.


Hezbollah is the most prominent proxy acting at the behest of the Supreme Leader of Iran in Syria. Along with the IRGC-QF, the group provided (and still does provide) military and ideological training to Iran-backed militias and led them in battle throughout the war. Moreover, Hezbollah troops fought all across the country, including on the Jordanian and Lebanese borders, Aleppo, and the Golan Heights.

Under Iranian direction, Hezbollah entered the Syrian Civil War on Assad’s side in 2011. Hezbollah spent the first two years of the civil war denying its involvement for fear that it would provoke opposition in Lebanon, but in April 2013, Secretary-General Hassan Nasrallah openly declared Hezbollah’s foray into the conflict, urging his followers to not “let Syria fall in the hands of America, Israel, or Takfiri (radical Sunni) groups.” Since then, Hezbollah has deployed approximately 5,000-8,000 fighters into the Syrian arena, and between 1,000 and 2,000 of them have been killed. 

The group has been involved in almost every major battle of the war, including the repeated offensives in Qalamoun and Zabadani, but most critically the battle of Aleppo. The battle of Aleppo ended with a regime victory in December 2016, irreversibly turning the tide of the Syrian war. Hezbollah’s role in the Aleppo offensive was critical to the Assad regime’s victory. The Syrian army’s heavy, mechanized units were not particularly effective in urban environments. Hezbollah trained and advised the Syrian army and pro-Assad militias to fight against a lightly armed guerrilla opposition in urban areas. Hezbollah troops also deployed alongside the Syrian army and its commanders took charge of militias. Its fighters’ ability to communicate with Syrians in Arabic made them an asset, compared to their Iranian counter-parts who speak Persian (Farsi).

After averting the direct rebel threat to Damascus, Hezbollah acted to re-extend the Assad regime’s control over all of Syria. In May of 2017, Hezbollah’s Secretary-General Hassan Nasrallah announced the withdrawal of his forces from positions on the Lebanese-Syrian border. Rather than demobilizing, however, they were sent deeper into eastern Syria, alongside the Syrian army, as part of a large-scale offensive to retake the country’s borders with Jordan and Iraq. At the same time, Iran-backed militias in the PMF charged from the Iraqi side of the border. In 2018, Hezbollah and other Iran-backed militias linked up with Iranian proxies on the Iraqi side, defeating ISIS and securing the Abu Kamal / al-Qaim border crossing west of the Euphrates River. South from Deir Ezzor City through Mayadin to Abu Kamal, the IRGC and Iran-backed militias—approximately 4,500 armed personnel in total—hold “full military authority and executive administration.”

While the number of Hezbollah fighters in Deir Ezzor has decreased since the victory over ISIS, Hezbollah continues to recruit, train and assist local militia groups in this predominantly Sunni Arab area. Prominent Iran-aligned Iraqi militias and Syrian Local Defense Force militias continue to be stationed in this area, indicating the strategic value to Iran. The city was the target of recent U.S. and Israeli military action. In February 2021, the U.S. carried out airstrikes on military infrastructure in the city in retaliation for rocket attacks on a U.S. base in the northern Iraqi city of Erbil. In September 2021, an Iran-backed militia convoy was struck, though neither the U.S. or Israel claimed responsibility.

Hezbollah is spread out across the country. Given the strategic importance of the highway that passes through Deir Ezzor province, it is no surprise that Hezbollah (along with the IRGC and Iran-backed militias) has maintained its presence in this region, but the group has also established key positions in the southern suburbs of Damascus, near the Sayyida Zainab shrine, as well as in Daraya, a suburb in the southwest of the Syrian capital. Since at least 2016, Hezbollah has sustained a demographic-change campaign to solidify regime control over Damascus enclaves. Regime forces, backed by Shi’a militias, began systematically displacing residents of Daraya in August 2016. The Assad regime and Iran’s IRGC coordinated efforts to target and remove Sunni populations from these areas.

In the southern suburbs of Damascus, Hezbollah’s demographic-change campaign is ongoing as of January 2022, Diyaruna reported. The Diyaruna report noted that Afghanis and Iraqis are being moved in to replace locals that were living near the Sayyida Zainab shrine, as Hezbollah sets up a military base in this area. The group is constructing underground tunnels at this old military site, which could be used to store drones and missiles. The tunnels are intended to protect against Israeli airstrikes, which intensified throughout 2021. Hezbollah is also using this military site for unmanned aerial vehicle (UAV) training operations. However, the group’s expansion into this area has been unpopular among locals, who view the shrine as one of the holiest. Hezbollah has removed farmers from their land allegedly to prevent them from documenting their military activities.

Another important shrine that is attracting Hezbollah militiamen, along with members of Syria’s 4th division, is the Sayyida Sakina shrine, located in Daraya, a suburb of Damascus. Iran built the shrine, though its location had no religious significance, and today it is the third most holy Shi’a shrine for Iranian people, said a local Syrian researcher. The shrine, built near the municipality building against the protests of local people, acts as the centerpiece of a kind of settlement, where Iran-backed forces now live. Here, Hezbollah and Assad’s army are acquiring housing, either by force or for large sums of money. They have also reportedly looted houses. Other Iran-backed militias present in this region include the Fatemiyoun Division, Liwa Abu Fadl al-Abbas, al-Maqdesiyoun, and Harakat al-Nujaba.

To counteract local opposition to its activities, Hezbollah engages in efforts to build popular support for itself and Iran. Hezbollah runs an organization called Jihad al Bina, which plays an active role in the construction of schools and field hospitals in Deir Ezzor and other government-controlled cities. Iran funds the organization. The Hussein Organization is another so-called charity that, along with Jihad al-Bina, delivers services that the government fails to provide. These organizations provide food baskets, repair homes, rehabilitee water pipes, and supply generators to provide electricity in the war-torn area. In 2007, the U.S. Department of the Treasury prohibited transactions between Jihad al Bina and any U.S. persons and froze its assets.

Hezbollah’s soft power campaign in Deir Ezzor is only one of many indications that Hezbollah intends to remain in the country after an eventual Assad victory. To that end, it is entrenching itself militarily, similar to its Iranian backers. In December 2021, Hezbollah reportedly began installing air defense systems in the Qalamoun mountains. These systems threaten to weaken Israeli’s ability to conduct air operations against key Hezbollah targets located in the Bekaa valley. Both tactical surface-to-air missile systems and man-portable air defense systems are suspected to be a part of this arsenal.  Furthermore, Hezbollah has reportedly established missile bases in Qusayr and Qalamoun to better protect its longer-ranger projectiles from Israeli aerial attacks.

The group is also aiming to establish a presence on the Syrian side of the Golan Heights. Their presence in this area concerns the Israelis because it could serve as a base to carry out limited strikes against soldiers or civilians in Israeli-held territory in a future conflict. However, this does not threaten Israel’s military superiority in the area. Since the Israelis occupy the high-ground, IDF ground troops can easily seize the flat terrain between the Golan and Damascus.

Israeli security officials say Hezbollah is exploiting the chaos of Syria’s civil war to clandestinely import advanced, balance-altering weapons—allegedly including chemical weaponsSCUDs, and Yakhont anti-ship missiles—from its Iranian patron and the Assad regime. In 2016, the U.S. Department of State reported that Hezbollah had already possessed anti-ship and anti-aircraft cruise missile systems. These weapons would be a major upgrade from the short-range and unguided katyusha rockets that have been the group’s traditional mainstay, and which make up the bulk of its oft-mentioned arsenal of 150,000 rockets. Israel considers these shipments to be a red line and has repeatedly intercepted and destroyed these weapons with air strikes. Even the unsophisticated katyusha rockets have the potential to reach population centers in Israel.

Many of the rockets and other weapons in Hezbollah’s growing arsenal were first flown into Damascus Airport from Iran and then trucked across the border into Lebanon. Ground transportation through Iraq and Syria remains a viable option given Iran’s control of the Abu Kamal / al-Qaim border crossing, but Israel has become increasingly effective at gathering intelligence and targeting convoys and storage facilities used to house weapons en route to Lebanon. In an effort to avoid Israeli airstrikes, Hezbollah recently took to transporting weapons via the sea as well. An April 2021 article in Breaking Defense reported that Iran was smuggling weapons from the Red Sea, through the Suez Canal, and into the Mediterranean Sea under the protection of a Russian fleet.

Hezbollah has engaged in large-scale sectarian cleansing of Sunnis in Madaya and Zabadini to secure its Beqaa Valley and Baalbek strongholds across the border and guarantee its land corridor to Damascus. Critically, an Iranian-Qatari brokered population swap deal in April 2017 transferred almost all remaining Sunni combatants from the area, in exchange for the Shiite residents of besieged Foua and Kefraya.

In March 2021, Lebanese Hezbollah militiamen were conducting military training camps in northeast Syria for the Shabiba, a brutal militia of predominantly Shi’a and Alawite people widely believed to have committed the Houla massacre in 2012 in which 108 people (mostly Sunni) were killed, many of them women and children. These sectarian acts of violence by Shi’a militias generate fear and resentment among the Sunni population; thus, Sunnis become more inclined to join radical Sunni groups to combat the Shi’a militias. When attacks by Sunni groups increase, so does the motivation to join radical Shi’a groups. In effect, Iran’s revolutionary project fuels a vicious cycle of radicalization, which could result in the regrouping of ISIS.

In many ways, Hezbollah has had success in replicating itself throughout Syria. The Iranian proxy group recruits and indoctrinates members of the minority Twelver Shi’a population in Syria into the ideology of the Islamic Republic of Iran, Velayat e-Faqih, which grants authority to the Supreme Leader of Iran. Hezbollah has even reached out to Sunnis, with some success at converting them to the Twelver Shi’a faith. For example, Hezbollah helped recruit from the Sunni tribe, al-Baggara, in the west of Deir Ezzor province. These recruits joined the Baqir Brigade, one of the most prominent militias within the Local Defense Forces, and some of them converted to Shiism. Ideological training is an important dimension of Hezbollah’s efforts to construct a network of militias in its image.

To this day, the group continues to recruit and train militias in Syria and lead extensive soft-power initiatives, including building schools, religious shrines, and cultural centers with funding from Iran. These initiatives are designed to build popular support for Hezbollah and the Iranian regime and cement their sociocultural influence in the country.

Hezbollah may also be involved in trafficking drugs through Syria into Jordan. Since the beginning of 2022 alone, Jordan’s army has expanded its operations to confront drug trafficking at its border. The army foiled attempts to smuggle 16 million amphetamine-type Captagon pills and killed 30 smugglers at the border with Syria, said Jordan’s army. The smugglers are said to be increasing the sophistication of their drug smuggling operations by employing drones. While the origin of the pills was not clear, Captagon is mostly manufactured in Lebanon and Syria, and Hezbollah is known to be involved in smuggling the drug out of its country to finance its operations. A Syrian opposition website reported in May 2022 that Hezbollah operatives from Baalbek had arrived in the southwestern Syrian city Al-Suwayada to oversee the construction of a small Captagon factory.

Additional Shiite Militia Proxies

In addition to Hezbollah, Iran has mobilized, funded, and armed thousands of Shiite fighters to defend Assad’s regime, inflaming Sunni-Shiite sectarian tensions in the process. These fighters, recruited from across the Arab and Islamic world, including IraqAfghanistan, and Pakistan, were brought under the unified command of Qassem Soleimani.

An estimated 3,000 Afghans, primarily immigrants, and refugees residing in Iran and Syria, form the Liwa Fatemiyoun (Fatemiyoun Division). Afghan children as young as fourteen have died in combat in Syria, revealing the IRGC’s shockingly unscrupulous recruitment practices. The U.S. government designated the Liwa Fatemiyoun as a terrorist organization in 2019. Additionally, an estimated 1,000 Pakistanis were trained in Mashhad under the IRGC Quds Force. The Iranian press describes this group, known as the Zainabyoun Brigade, as an elite assault force. The core forces of the Zainabyoun Brigade reportedly initially came from Al-Mustafa International University, an Iranian network of colleges and seminaries tasked with disseminating Iran’s religious ideology around the world.

In January 2021, the Afghan Fatemiyoun Division reportedly transferred 56 short and medium-range surface-to-surface missiles over the Iraqi border to Iraqi Hezbollah forces positioned in Syria’s eastern Deir Ezzor province, disguising the weaponry by using vehicles meant for transporting produce. Iran’s military entrenchment has eroded Syria’s sovereignty and invited increased Israeli strikes on Syrian territory, indicating that as the Syrian Civil War calms down, the country may become embroiled as a battleground between Israel and Iran and its proxies.

Iran’s efforts to recruit Shi’a militants to the Syrian war effort from around the Middle East and beyond center upon the salaries it offers its disaffected conscripts. Recruits are offered monthly salaries on a sliding scale dependent on country of origin and level of military training. Iran offers to pay the families of “martyrs” for their children’s education and to send family members on annual pilgrimages to holy sites in Iran, Iraq, and Syria. The salaries are clearly intended to exploit the economic misfortune caused by the war.

Iran’s monetary incentives have been effective at recruiting people within Syria as well. In January 2022, the Syrian army was struggling to recruit new fighters in the Deir Ezzor region, even though they were offering defectors and rebels amnesty, because many of these fighters chose to sign up with Iran-backed militias, which offer more attractive benefits, including higher wages. Since the Iran-backed militias are more powerful than the state forces, they also offer a form of protection against the state and terrorist groups. In fact, recent attacks by ISIS added to the motivation to join Shi’a militias. Now that the Syrian civil war is winding down, the Assad regime and the Iranians are beginning to compete with each other for influence and control.

To grow its base of support in Syria, Iran has recently increased its efforts to convert Sunnis to Shiism, particularly in the predominantly-Sunni Deir Ezzor province. The Shiite call to prayer can be heard from mosques; and religious shrines are being built at locations with religious significance. Iran also relies on material inducements to get people to convert: it has bought property and guaranteed housing to Shi’a converts; and Iran-backed militia leaders have even paid people to become Shi’a. Syrian authorities have reportedly arrested Sunni imams for refusing to participate in Shi’a prayers. Furthermore, Iran offers financial assistance to tribal leaders in Deir Ezzor, and in return these leaders have helped the Iranians build religious schools and centers.

Beyond cash and benefits, Iran relies heavily on religious and ideological appeals to find recruits willing to be martyred for the cause. The New York Times detailed how recruiters affiliated with the IRGC appeal to the Shi’a faith and identity of potential fighters, reporting that once recruited, fighters train near Tehran where “Iranian officers delivered speeches invoking the martyrdom of Imam Hussein, the revered seventh-century Shiite figure whose death at the hands of a powerful Sunni army became the event around which Shiite spirituality would revolve. The same enemies of the Shiites who killed the imam are now in Syria and Iraq, the officers told the men.” These sermons further exacerbate Sunni-Shi’a tensions and violence.

Iran has sought to frame the fighting in Syria as an urgent necessity to defend Shi’a shrines. The golden-domed Sayyeda Zainab shrine, strategically located in south Damascus, is central to this narrative of Iran and its proxy fighters. Attendees at funerals for Lebanese Hezbollah and other Shi’a militia fighters killed in Syria frequently chant “labaykya Zainab” (At your service, O Zainab), and these same groups have also produced propagandistic songs featuring the slogan and placed the shrine’s iconic dome prominently in the background of martyrdom posters of fallen fighters.

One of the most important and notorious of those groups is Harakat Hezbollah al-Nujaba, which played a critical role in the battle for Aleppo and is alleged to have summarily executed 82 civilians—including 11 women and 13 children. Harakat al-Nujaba, an offshoot of Kataib Hezbollah and Asaib Ahl al-Haq, recently formed a “Golan Liberation Brigade” to fight the Israelis.

In March 2021, Syrian opposition media outlets reported that the Iran-backed militia Kataib al-Imam Ali had opened a recruiting station in the regime-controlled city of Aleppo. Kataib al-Imam Ali was created in Iraq in June 2014 as the armed wing of an Iraqi political party, Harakat al-Iraq al-Islamiyah (The Movement of the Islamic Iraq). The group has been uniformed and well-armed since its inception. It was founded by Shibl al-Zaydi, a U.S. designated terrorist who has leveraged his position as head of a powerful militia to become one of the richest men in Iraq with a large business empire and controlling interest in the Iraqi Ministry of Communications. 

Assad regime defense officials reportedly approved of the group’s recruitment operations and have made allowances not to pursue army defectors and dodgers of compulsory military service if they instead join the militia. The militia appeals to economically disenfranchised Syrian youth, offering $200 per month for married recruits and $150 per month for single individuals. The group’s nascent presence in Syria is a testament to many of the Iran-backed Shi’a militias' transnational nature.

Local Actors

Iran exploits Shi’a religious beliefs and indoctrinates people to motivate them to fight for Iran’s interests. Unlike radical Sunni groups, which threaten the ruling-establishment of Sunni-led states, almost all radical Shi’as are influenced by Iran’s state ideology and its revolutionary project. Therefore, Iran pursues a radicalization policy in Syria.

One of the most pernicious ways in which Iran has sought to bolster its influence along sectarian lines in Syria has been by providing ideological guidance for the transformation of elements of Bashar Al-Assad’s Popular Committees—small, localized defense units—and other irregular pro-Assad armed groups into increasingly “regularized” militias, known as the National Defense Forces (NDF), modeled after Hezbollah. Iran’s Qassem Soleimani and Hezbollah personally oversaw the creation of the NDF, whose local Syrian recruits receive training in urban and guerilla warfare from both the IRGC and Hezbollah at facilities in Syria, Lebanon and Iran. The NDF has participated in critical battles, including the 2016 Aleppo offensive and the campaign to dislodge ISIS, contributing to Assad’s surging territorial reconquests. In a 2017 offensive to take back Deir Ezzor from ISIS, the NDF allegedly committed war crimes and human rights abuses against the local Sunni population.

The militia operates as a part-time volunteer reserve force of the Syrian Army which has opted to fight on behalf of the Assad regime against rebel groups, filling the void created by the depletion of Assad’s Syrian armed forces since their creation in mid-2012. Iran has taken the lead in the “rebranding, restructuring, and merging” of the Popular Committees into the NDF, with Hezbollah playing a critical role in providing military and ideological training. In a similar vein to Hezbollah, the Iran-backed NDF operate in a localized context and are ostensibly Syrian actors, but their true raison d’etre is the propagation of Iran’s supranational revolutionary project.

The NDF is now by far the largest militia network in Syria, estimated at approximately 50,000 primarily Alawite members as of late 2015. The NDF also has a large contingent of Shi’a fighters who, despite being a small minority in Syria, have played an outsize role in supporting the Assad regime against the rebels, which were mostly Sunni. The NDF militants are more audacious than the average member of the regular Syrian army, according to one rebel, who added that they fight with “sectarian zeal.”

In addition to replicating the Hezbollah model in Syria, Iran’s role in creating the NDF also mirrors the establishment of the Popular Mobilization Forces (PMF), a loosely-knit coalition of predominantly Shi’a militias in Iraq, most of which continue to have close ties to Iran. Both the Syrian NDF and Iraqi PMF are governmentally-sanctioned and financed paramilitary outfits whose fighters are more numerous and powerful than their respective states’ official defense forces. Furthermore, both were formed on a sectarian basis: the NDF mobilized the Alawite community on the basis of a need to defend it against Sunni rebels, and subsequently ISIS; and the PMF was formed after the Grand Ayatollah Ali Sistani, the highest Shi’a cleric in Iraq, issued a fatwa calling on all able-bodied people to join a militia and fight ISIS. The areas in Iraq that were liberated from ISIS are largely under control of the PMF. In Syria, prominent Defense Force militias, such as the Baqir Brigade, operate alongside other Iran-backed militias to control the areas they liberated from ISIS. PMF militias have taken control of the roads and levy taxes in Iraq. Likewise, at the Abu Kamal / al Qaim border crossing, these militias generate billions in tax revenue.

A further similarity is that Iran pressured the Iraqi government to integrate the PMF within the state security apparatus, just as it pressured Assad to integrate the NDF. There are some notable differences, though, between the PMF and the NDF. While Iran played a role in the formation of both units, today it appears to enjoy more loyalty from the PMF than it does from the NDF. Most of the Shi’a militias which make up the PMF continue to act at the behest of the Supreme Leader of Iran, even though the group is legally under control of the Prime Minister’s office. On the other hand, Iran is pleading with the NDF in parts of Syria to gain their loyalty, offering to provide financial support.

The NDF appears to be a permanent fixture in Syria, remaking a country that historically “was home to many competing ideological forms of Shiism” in Iran’s image. The militia’s secure Iranian alignment and loyalty to its revolutionary ethos ensure that Iran will be the dominant military and cultural power in Syria for the foreseeable future.

Another way Iran strives to remake Syria in its own image is by penetrating the educational system. In January 2018, Iran announced plans to establish Islamic Azad University branches in Syrian cities, which would allow it to spread its Islamic revolutionary ideology. Iran has also taken measures to indoctrinate young children. Iran is spreading Shiism in the west Euphrates area, which resembles “ISIS policy of recruiting and brainwashing children during its control of large areas of Syrian territory.” According to The Syrian Observatory for Human Rights, 20 children under the age of 12 were introduced to Shiism at a school in the town of Hatlah, and given money and gifts for attending the lesson. These material inducements may be intended to exploit the poverty of the population for the purposes of propagating Iran’s particular brand of Islam.

The clerical regime in Iran has largely abandoned any pretense of pan-Islamism to focus exclusively on the Shi’a non-state proxy model, with the aim of dominating the region through loyal Shi’a legions. Iran takes advantage of poverty, chaos, and war to achieve these aims.

Iran’s Gains in Syria

The successes of Hezbollah, the NDF, and affiliated Iranian proxy forces in the Syrian theater have expanded Iran’s objectives within Syria. What began as an Iranian-sponsored attempt to create a “Useful Syria” from the regime’s major cities and economic centers has now become a more ambitious campaign to retake the entire country. Iran’s provision of economic, military, and proxy support was critical in stabilizing Assad’s rule until Russia’s entry into the civil war in 2015.

Following the Syrian regime’s 2016 victory in Aleppo, which followed on the heels of Russia’s entry into the conflict, the civil war’s momentum swung decisively in Assad’s favor. In 2018, the Assad regime consolidated its control in a brutal fashion, pressing an offensive in Eastern Ghouta, the last rebel-held bastion in the Damascus suburbs. The Eastern Ghouta campaign forced the remnants of rebel forces and thousands of civilians to flee to Idlib province, which is now Syria’s last-remaining rebel-held enclave on the western Syrian corridor that runs from Damascus-Homs-Hama-Idlib-Aleppo. As of January 2022, millions of displaced people in this province were living under the rule of Hayat Tahrir al-Sham (HTS), a jihadist group that became notorious during the Syrian Civil War for suicide bombings against government and civilian targets.

Former Iranian Foreign Minister Mohammad Javad Zarif euphemistically declared that Idlib, whose population has doubled to 3 million people since the war broke out due to internally displaced refugees, must be “cleaned out” of opposition forces. The U.N. has warned that a regime offensive backed by Iran and Russia would result in the “worst humanitarian catastrophe” of the century as there are no longer any opposition-held areas left in Syria where those fleeing can evacuate. In September 2018, Russia and Turkey negotiated a tenuous truce to forestall a bloodbath in Idlib, but the Assad regime has referred to the deal as a “temporary one.”

In October 2019, President Trump hastily announced the withdrawal of U.S. forces from northeast Syria and signaled his intention to eventually end US involvement in Syria. The troop withdrawal effectively strengthened Iran’s hand and will facilitate further Iranian military and commercial entrenchment in Syria, presenting a self-inflicted setback to the administration’s concerted effort to pressure Tehran. The U.S. troop withdrawal also increased the chances of a Russian-Syrian-Iranian onslaught in Idlib. Turkey, concerned that an offensive would further increase refugee strains, had stood as a major impediment to an Idlib offensive. In the aftermath of the U.S. withdrawal, however, Turkey has drawn closer to Russia, neutralizing its protestations over a “fait accompli” in Idlib.

At a December 2019 summit in Kazakhstan as part of the Russia-Iran-Turkey negotiation track, Turkey joined Russia and Iran in expressing concern over the increased presence of “terrorist groups” in Idlib, and pledged to work cooperatively to pacify the situation. The pledge came in the wake of increased activity by Syrian armed forces, in conjunction with Russian air power, on the outskirts of Idlib in the weeks prior. In November 2019, Syrian and Russian forces killed at least 22 civilians in attacks on an internally displaced person (IDP) camp and a maternity hospital in villages around Idlib, according to opposition monitoring groups. These events indicated that a full-scale offensive in Idlib was imminent.

The Kazakhstan summit ended without a definitive ceasefire agreement, and in the days that followed, Syrian government forces, Russia, Hezbollah, Iran, and other pro-Assad militias launched an offensive to retake Idlib. Nearly one million Syrians, roughly half of them children, were displaced by the fighting, straining U.N. relief efforts. In March 2020, Russia and Turkey agreed to a ceasefire, but the situation remains volatile.  

A second consequence of the U.S. troop withdrawal from northeast Syria was that it weakened the deterrent that allowed the Kurdish-led SDF to control a full third of Syria’s territory, home to the country’s richest oil and agricultural resources, keeping it out of the hands of the Russia-Assad-Iran alliance for seven years. As of January 2022, though, the SDF, backed by a U.S. troop presence at the former Conoco gas facility, still controlled the al Omar oilfield, the largest oilfield in the country, in the eastern part of Deir Ezzor. In August 2020, the SDF signed a contract with an American oil company to extract oil from this lucrative oilfield. The U.S. also conducts counterterrorism operations out of the Conoco base and recently participated in joint military exercises with the SDF in Deir Ezzor, near the Iraqi border.

Iran and Iran-backed forces control most of the territory across the Euphrates River from the Conoco base. Further south, the Abu Kamal / Al-Qaim border crossing in Deir Ezzor is, perhaps, the most essential Syrian territory to the Iranian regime, as it serves as the only major route between Syria and Iraq under its control. That is why a large number of Hezbollah forces and the IRGC are stationed there, and west of the Euphrates River. This route—one out of three major routes into Syria from Iraq—is known as the upper passage of the southern route, and it skirts alongside the western edge of the lush Euphrates River Valley, passing through Deir Ezzor city, and eventually connecting to Aleppo, which, as noted, is largely controlled by the Syrian regime.

There is also a lower passage of the southern route, passing through al Tanf; and the third major route, known as the northern route, passing through al Yarubiyah. Of course, overtime, Iran has adapted its transport routes to avoid detection and Israeli airstrikes, but the Abu Kamal / al Qaim border crossing remains key. As of 2019, the Atlantic Council concluded that neither the southern-most nor the northern-most causeway were open to Iran, with the U.S.-held al Tanf garrison and U.S.-backed forces obstructing the al Tanf causeway; and the Syrian Kurdish People’s Protection Units (YPG) holding al Yarubiyah. Given the vulnerability of the Abu Kamal / al Qaim crossing to detection and airstrikes, Iran has occasionally resorted to transporting materials via illegal border crossings on unpaved roads.

Two-hundred U.S. troops still occupy a military base at the strategic al Tanf border crossing to conduct counterterrorism operations, while also limiting Iran’s ability to ship weapons along this southernmost transit route from Baghdad to Damascus. However, Iran-backed militias and pro-regime forces began establishing a presence outside the U.S.-enforced 55-kilometer “de-confliction” zone at al Tanf. Despite U.S. warnings, the Assad regime and allied forces—including Hezbollah and other Iranian proxy militias—established a presence at the key al-Tanf border crossing. These maneuvers indicate the strategic value of al Tanf and create a potential “flashpoint” for escalation between the U.S. and Iran. Iran is looking to open a second route, which would make it more difficult for Israel to track down and prevent arms shipments through Syria.

In October 2021, a coordinated UAV attack was carried out by Iran on the al Tanf U.S. military base in what American and Israeli officials believed to be retaliation for an Israeli airstrike in Syria. Iran may be trying to push Biden to withdraw the remaining U.S. forces from the Middle East, or make concessions in the ongoing nuclear negotiations. Since Biden took office, the Iranians have carried out increasingly dangerous and frequent attacks on U.S. personnel and facilities in both Syria and Iraq. Between January 20, 2021, when Biden took office, and July 2021, Iran-backed militias had carried out 20 rocket attacks and 11 drone attacks on U.S. assets in Syria and Iraq, a significant increase compared to Trump’s time in office.

Iranian proxy attacks on U.S. bases in Iraq and Syria increased again in 2022. There were seven attacks in May 2022—as many as in February, March, and April combined. Although they did not result in any deaths, the attacks tested the Biden Administration’s red lines. Whereas the Trump Administration made clear that it would respond if Americans were injured or killed in proxy attacks, the Biden Administration has been less clear about its red lines. Nor did the U.S. respond with force to any of the 29 attacks launched on U.S. bases in Iraq and Syria between October 2021 and August 2022. The failure to establish clear red lines, backed up by kinetic action, allows Iranian proxies to carry out attacks with impunity.

Some analysts view these brazen attacks as a signal from the Iranian system that it will take a more aggressive stance against U.S. presence in the region because it fears no consequences. In this way, it could increase pressure on the U.S. to withdraw and agree to concessions in the Vienna negotiations on the nuclear deal. Through the PMF, Iran may also be planning to increase its pressure on U.S.-backed forces.

Head of the Iraqi Popular Mobilization Authority, Faleh al-Fayyad, reportedly traveled to Damascus in March 2022 to meet with President Bashar al-Assad in order to discuss border security cooperation, with the aim of restricting the activities of the Kurdistan Workers Party (PKK), and shoring up security coordination on both sides of the border at the behest of Iran. Another possible intention behind Al-Fayyad’s trip may have been increasing pressure on the US-backed Syrian Democratic Forces (SDF), which have a major presence in northeast Syria.

If President Biden brings the remaining troops home, the Iranians would be in an improved position to take full control of the remaining bordering crossings and seize key oilfields. Iran has already begun to invest in its relations with eastern Syrian tribes, like the Baggara tribe, who are poised to take over SDF-controlled regions in the event of a US withdrawal.

The Syrian border with Jordan is also of considerable importance, given that Jordan provides a land bridge to wealthy Gulf markets. Pro-Iranian Syrian army units are reportedly cooperating with Iran-backed militias to control the flow of drugs from Syria into Jordan. The smuggling operations are a critical source of revenue for the militias, which have received less money from Iran ever since the U.S. reimposed sanctions in April 2018. The constant flow of drugs from Syria into Jordan has resulted in a “drug war,” in which the Jordanian military and law enforcement frequently engage armed smugglers. In May 2022, the Jordanian army said it was bracing for an escalation, as the armed smugglers attempt to export larger quantities of drugs.

Most common among the drugs smuggled through Jordan from Syria is the Syrian-made cheap amphetamine known as Captagon, which is usually taken in a pill form, and is frequently used by combatants in war to alleviate fatigue. Amid the instability of a civil war, the lucrative trade in Captagon pills has become central to Syria’s illicit economy. Although the Syrian government denies its involvement in the multi-billion-dollar industry, the country now contains the main production sites for this drug.

A New York Times article from December 2021 referred to Syria as a “narco-state,” given the fact that associates and relatives of President Assad control the trade. Brigadier General Ahmed Hashem Khalifat, director of the Border Security Directorate in the Jordanian Armed Forces, alleged, “Undisciplined forces from the Syrian army are collaborating with drug smugglers. The gangs…are supported by these forces and by the security apparatuses, in addition to Hezbollah and Iranian militias.” Hezbollah and other Iranian militias, therefore, appear to be facilitating the drug trade in support of the Assad regime.

The U.S. military presence in Syria, and the U.S.-backed Syrian Democratic Forces, are helping to prevent Iran from taking control of the remaining roadways from Iraq into Syria. If these valuable strategic assets come into Iran’s possession, Iran would have an easier time shipping weapons to its terrorist proxy in Lebanon, along with the variety of proxy forces it supports throughout Syria. It would also be easier to resupply the Assad regime. The U.S. is also preventing Iran and Syria from seizing key oilfields in the northeast of the county.

Iran’s Long-Term Influence in Syria

Iran’s Syrian intervention has clearly paid off, guaranteeing both Assad’s survival and dependence on Tehran given his weakened position both domestically and within the international community. For its efforts to shore up Assad, Iran and the IRGC—which has a hand in virtually every sector of the Iranian economy—have the opportunity to further carve out a long-term role for themselves in Syria, utilizing ideology and the cover of military and economic projects to export the Islamic Revolution by creating Shi’a militias and quasi-state institutions loyal to Iran and its Supreme Leader within Syria.

Iran relied on both local and foreign proxies—trained, funded, armed and directed by the Islamic Revolutionary Guards Corps-Quds Force (IRGC-QF) and Hezbollah—to defend Assad against the rebel forces and accomplish core foreign policy objectives. As of March 2021, Iran and Iran-backed militias controlled the outskirts of Damascus, patrolled strategic towns on the Syria-Lebanon border, were present in large numbers in southern Syria near Israel, had multiple bases in Aleppo, and camps in the west of the Middle Euphrates River Valley (MERV), near the border with Iraq. Through its growing proxy network in Syria and its local support, Iran can exert leverage over the central government and coerce Assad to make decisions in its favor, like appointing Iran-aligned figures to key positions in the government, military, or other institutions or providing Iran with lucrative contracts.

Furthermore, Iran uses its Shi’a proxies in Syria to project power into the Levant with a low risk of escalation, for Iran can deny its involvement in the attacks it directs through proxies. Iran continues to direct attacks on U.S. assets and Israel and denies any involvement. Iran and its proxies now threaten Israeli positions in the Golan Heights, thus opening the possibility of a two-front war with Israel, and have taken an increasingly confrontational posture against the U.S. as well.

Iran plans on using Syria as a base from which to provoke the U.S. and its allies and is not concerned about dragging Syria into its proxy battles. Moreover, Assad permits Iran’s expansive military and proxy operations throughout the country, including its weapons shipments and attacks on Israel. He continues to grant permission for these activities even though they increase the risk of Israeli strikes on Syrian interests. For example, in a significant military escalation, Israel struck 70 Iranian military sites throughout Syria in retaliation for an unprecedented rocket attack on Israeli targets in the Golan Heights conducted by Iran in May 2018; 5 Syrian soldiers were killed. In December 2021, Israel bombed a storage container holding Iranian munitions in the Syrian port of Latakia.

Russia cooperates with Israel when Israel carries out airstrikes in Syria. Russia agreed to allow Israel to carry out these strikes, and does not target Israeli jets. However, former Israeli Foreign Minister and former Prime Minister Yair Lapid’s accusations that Russia had committed war crimes in Ukraine raised the prospect that the two countries’ security cooperation could gradually unwind. The Russians may not turn their air defense systems on Israeli jets in Syria’s skies, but there are other ways that Russia might impede upon Israel’s security objectives in Syria. Military analyst Brigadier General Asaad Al-Zoubi claimed that Russia is sending a signal to Israel by allowing Iran to move its forces closer to the Israel border with Syria.

Iran’s Foreign Minister Hossein Amir-Abdollahian traveled to Damascus in March 2022 to affirm support for the Syrian regime after Russia’s invasion of Ukraine. Some members of Syrian President Bashar al-Assad’s inner circle do not appear to be opposed to a growing Iranian presence in Syria, as one of his advisors suggested in an interview with the BBC, that Iran is still needed to support Syria’s war. Other members of the president’s inner circle reportedly want the Iranians out of the country, including the powerful General Maher al Assad, the president’s brother and commander of the Army’s notorious 4th Division.

President Assad had already expressed his own discontent with Iran’s military activity by ejecting Iran’s top commander of forces in Syria, General Javad Ghaffari, in November 2021. The general, who came to be known by the opposition as the “butcher of Aleppo,” was reportedly asked to leave the country because he was directing proxy attacks without approval from Syrian officials. Iranian accounts of this situation have dismissed the notion that he was fired. If it is true that Assad asked Ghaffari to leave, this suggests that the Syrian leadership still maintains a grip over militia activities in Syria, and there is tension, at times, below the surface with Tehran. A Saudi news channel operated by Al Arabiya ascribed the Syrian president’s decision to eject Ghaffari to an allegation that he had led “a number of activities against the US and Israel that almost led to the entry of Syria into a regional war, including the attack on American targets in Syria on October 20 by Iranian-backed militias,” the Times of Israel reported in November 2021.

It is not clear how President Assad will address these divisions within his inner circle. On the one hand, President Assad has regained control over the country, and may wish to see the Iranian military and proxy presence in his country wind down, so that he can reassert his authority. On the other hand, the Assad regime will still need Iranian security support, given a shortage of resources. And it is possible that that need increased when Russia withdrew some of its forces. Nonetheless, President Assad’s ability to dictate outcomes in his country is clearly limited, given the extensive involvement of foreign powers, including Iran, Turkey, Russia, and the U.S.

When the presidents of Russia and Turkey gathered in Iran in July 2022, Syria, still a top foreign policy priority for Iran, likely featured prominently in the discussions, especially amid Turkey’s threats to expand its military operations in the north of Syria. President Raisi issued a statement claiming, “Syria’s fate should be decided by the people, without foreign intervention.” Of course, Raisi was not referring to Iran’s expansive presence. This statement was directed toward the U.S. military presence.

Iran, and its terrorist proxy Hezbollah, seem to be accelerating their military expansion into Syria, especially since the war in Ukraine required Russia to pull forces from Syria. The New York Times reported at the end of March 2022, that at least 1,000 Russian mercenaries from the infamous Wagner Group would be redeployed to Ukraine. This shift created a potential power vacuum in Syria that Iran may look to fill. According to Israeli sources, hundreds of Iranian personnel are moving into strategic areas that were previously dominated by the Russians, including the city of Aleppo and the Mohin warehouse area. Moreover, in May 2022, Hezbollah and Iranian forces began taking over military bases that were formerly occupied by Russian forces. 

The Assad regime’s re-consolidation of power, a project in which Iran played an indispensable role, has given Iran and its proxies a foothold to project economic, military, and cultural influence into Syria for years to come. As the civil war winds down, Assad will no longer need the Iranians and their proxy forces to remain in the country. However, Assad owes a huge debt to the Iranians for providing the material, financial, and military support to conduct the war against the rebels. Assad received oil and armaments, economic and military assistance, loans, and increased trade. And, of course, on the military side, Iran was indispensable: Iranian troops and proxies played lead roles in conducting ground operations, and training and commanding pro-Assad militias; Iranian proxies from throughout the Middle East supplied additional manpower; and Iran even recruited and mobilized fighters from within Syria.

Funeral in Tehran for a senior IRGC commander killed fighting in Syria in 2015.
IRGC-Quds Force Commander Qassem Soleimani, who is said to be running the war in Syria, addressing Iran-backed fighters near Aleppo in 2015.


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