The Iranian-Syrian alliance stretches back over three decades, constituting one of the most enduring partnershipsamong authoritarian regimes in the region. Iran views the maintenance of Assad’s control in Syria as a check against Sunni power in Syria and the greater Middle East. Through the Assad regime, Iran is further able to project its influence throughout the Levant. 

In a testament to Assad’s utility, the Islamic Republic of Iran and its proxies have played the critical role in saving and sustaining Bashar al-Assad’s regime amidst the ongoing Syrian Civil War, which began as a popular uprising in March 2011 as the “Arab Spring” swept the region. Officials of the Iranian regime have gone so far as to refer to Syria as “the 35th province [of Iran] and a strategic province for us.”

Syria has been so strategically vital to Iran because it provides a logistical “land bridge” to Hezbollah and access to Mediterranean ports, which is central to its regional ambitions.The regime also wants to deny a victory to its regional Sunni rivals, and further consolidate its “Shia Crescent” stretching from the Persian Gulf to the Mediterranean through Iraq, Syria, and Lebanon.

Not only does Iran remain the country's “closest ally,” declaring it will “support Syria to the end,” but Iran increasingly plays the commanding role in the Syrian Civil War against the rebel forces. In August 2012, Islamic Revolutionary Guard Corps (IRGC) General Salary About declared, “Today [Iran is] involved in fighting every aspect of a war, a military one in Syria and a cultural one as well.”

This steadfast support has continued throughout the administration of Iranian President Hassan Rouhani, a purported moderate. 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.

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 Quds Force. Beginning in 2012, Iran's economic support increased markedly to forestall the collapse of theAssad 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 today. 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.

Iranian Military Support to the Assad Regime and Provision of Proxies

Iran has directed the conduct of the conflict. The Iranian regime's support for Syria is broad and comprehensive, and includes deploying Iranian troops inside Syria, technical assistance, and training for Syrian forces. As early as December 2013, Islamic Revolutionary Guard Corps (IRGC) Maj.-Gen. Mohammad Ali Jafari boasted, “[Iran has] special forces transferring experience and training who are doing advisory work.”

Initially, Iranian support was limited to advising and training Assad regime forces. Iranian support to the Syrian regime 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. Subsequently, Tehran has greatly expanded its support to include deploying thousands of IRGC, Artesh and Basij fighters to take direct part in the Syrian Civil War’s battles.

Additionally, Iran has deployed an estimated 20-30,000 of its regional proxies from around the Middle East, Afghanistan, and Pakistan into the country. IRGC Quds Force commander Qassem Soleimani is at the head of these forces, coordinating activities among the various Shia mercenary forces and ensuring that their activities fulfill Iranian foreign policy objectives. As the Assad regime has weakened, it has become increasingly reliant on the local and foreign Shia militias beholden to Iran to seize and hold territory.


Under Iranian direction, Hezbollah entered the Syrian Civil War on Assad’s side in 2011 and has been critical to his regime’s survival. Hezbollah spent the first two years of the civil war denying its involvement, 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 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.

After averting the direct rebel threat to Damascus, Hezbollah has acted to re-extend the 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 as part of a large-scale operation to retake the country’s borders with Jordan and Iraq and to join with Popular Mobilization Forces charging from the Iraqi side of the border.

Hezbollah has made clear it intends to remain in Syria and is laying permanent groundwork for the day after an eventual Assad victory. Hezbollah has reportedly established missile bases in Qusayr and Qalamoun to better protect its longer-ranger projectiles from Israeli aerial attacks. It has also engaged in large-scale sectarian cleansing of Sunnis from the area 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.

The group is also aiming to establish a presence on the Syrian side of the Golan Heights, a matter of concern for the Israelis. This would not threaten Israel’s military superiority in the area, since the Israelis occupy the high-ground and the flat terrain between the Golan and Damascus can easily be seized by IDF ground troops. However, it could serve as a base for Hezbollah to carry out limited strikes against soldiers or civilians in Israeli-held territory in a future conflict.

Israeli security officials say Hezbollah is also exploiting the chaos of Syria’s civil war to clandestinely import advanced, balance-altering weapons – allegedly including chemical weapons, SCUDs, and Yakhont anti-ship missiles – from its Iranian patron and the Assad regime. 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 this a red line and has repeatedly intercepted and destroyed these weapons with air strikes.

Additional Shiite Militia Proxies

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

An estimated 3,000 Afghans, primarily immigrants and refugees residing in Iran and Syria, form the Liwa Fatemiyoun (Fatemiyoun Division). Approximately 1,000 Pakistanis, who receive training from the IRGC Quds Force in Mashad, comprise the Zainabyoun Brigade, which the Iranian press describes 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.

Iran’s efforts to recruit Shia 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, basic and advanced military training, and 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.

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 Shia 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.”

Iran has also sought to frame the fighting in Syria as an urgent necessity to defend Shia shrines. The golden-domed Sayyeda Zainab shrine, strategically located in south Damascus, is especially central to this narrative of Iran and its proxy fighters. Attendees at funerals for Lebanese Hezbollah and other Shia 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 prominently placed the shrine’s iconic dome 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.

Local Actors

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 recruitsreceive training in urban and guerilla warfare from both the IRGC and Hezbollah at facilities in Syria, Lebanon and Iran.

The NDF 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.

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) in Iraq. 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. 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 has participated in critical battles, including the 2016 Aleppo offensive and the campaign to dislodge ISIS, contributing to Assad’s surging territorial reconquests.

Iran’s Long-Term Influence 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. With the Assad regime and allied forces – including Hezbollah and other Iranian proxy militias – retaking the key Iraqi-Syrian border crossings of al-Tanf and Abu Kamal, and Iranian-sponsored members of the Popular Mobilization Forces reaching the Syrian border from the Iraqi side, Iran has completed a critical link in its project to create a land corridor to the Mediterranean.

Iran’s provision of economic, military, and proxy support was critical in stabilizing Assad’s rule until Russia’s entry into the Syrian Civil War in 2015.Following the regime’s 2016 victory in Aleppo, the war’s momentum swung decisively in Assad’s favor. In 2018, the Assad regime further consolidated its control in 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. Iranian Foreign Minister Mohammad Javad Zarif has 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.”

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. Iran’s Syrian intervention has 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 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.

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 began 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 has announced that indicates 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. In January 2018, Iran announced plans to establish Islamic Azad University branches in Syrian cities, a development which indicates that Iran is investing in spreading its Islamic Revolutionary ideology in Syria.

Both the NDF and Lebanese Hezbollah appear to be permanent fixtures in Syria as well, remaking a country that historically “was home to many competing ideological forms of Shiism” in Iran’s image. Hezbollah and the NDF’s efforts to secure Iranian alignment and loyalty to its revolutionary ethos,ensures that Iran will be the dominant military and cultural power in Syria for the foreseeable future. As Iran has further entrenched its control over Syria, it and its proxies have taken on increasingly confrontational postures against the U.S. and Israel. Iran has engaged in an armed drone skirmish with Israeli forces, and conducted a missile strike against ISIS fighters that landed within three miles of U.S forces. These incidents indicate that with its control and influence in Syria entrenched, 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.

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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