Foreign Fighters—From Many Lands
The composition of forces besieging Aleppo extended significantly beyond the Assad regime’s Syrian Arab Army (SAA). The offensive also involved Russian, Iranian, Iraqi, and Hezbollah elements, as well as an assortment of Syrian and foreign militias. In fact, throughout the Syrian conflict, the SAA gradually diminished due to casualties and defections, resulting in an increasing reliance on foreign forces.
At the start of the conflict, the SAA totaled 250,000 soldiers. By April 2015, the army consisted of 125,000 regulars and 125,000 associated pro-government militias. It is now estimated that militia elements outnumber army regulars in the Assad coalition.
This fragmentation of military force presents a grave threat to the ability to maintain order during any future Syrian settlement; it also challenges those who seek to determine responsibility and culpability for individual actions, as the evacuation of Aleppo demonstrated. Most of the reports of executions, and the major interruptions encountered during the evacuation process, were attributed to the myriad militias, whose motivations and interests diverge from the Syrian government and Russia’s.
In fact, the offensives during the last months of the siege of east Aleppo were composed of mainly foreign fighters. In early October 2016, an estimated force of 6,000 pro-government combatants descended upon Southern Aleppo. Of those 6,000, roughly 5,000 were foreign fighters, with only around 1,000 Syrian soldiers representing the Syrian army
Iranian Involvement
One of the largest pro-government militia forces in the conflict was the National Defense Force (NDF), which some estimates put at 100,000 strong. The NDF was founded in late 2012 by professionalizing hundreds of disparate pro-Assad militias to create a regionally based paramilitary wing of the Syrian military.
However, the NDF has significant links to Iran: its creation was supervised by the leader of the elite Iranian Quds Force, Qasem Suleimani. NDF troops have received direct training and guidance from Iranian and Hezbollah forces who are believed to be modeling the forces on the Iranian Basij militia.
The NDF played a major role in Aleppo supporting the SAA, including in the final assault. Shia militias, supported by Iran’s Revolutionary Guards, were also seen as essential in the ground operations that recaptured Aleppo in December 2016. Many such militias came in the form of Iraqi units, such as Asa’ib Ahl al-Haq (League of the Righteous), Abu al-Fadhil al-Abbas, and the Nujaba Front, all of which report to Suleimani.
Asa’ib Ahl al-Haq, in particular, gained notoriety for their involvement in Syria. The photos below allegedly show their forces in a parade in southern Aleppo in March 2016.


In September 2016, Mohammad-Bagher Soleimani, an Asa’ib Ahl al-Haq field commander, was confirmed dead after fighting in Aleppo. He is shown below kneeling next to Qasem Suleimani (center)

Iranian militias were also allegedly involved in a string of executions that took place during the last couple of days of evacuations in eastern Aleppo. The UN’s OHCHR relayed that it received reports that Iraqi militia had shot scores of people as they fled their homes in the remaining neighborhoods of east Aleppo.
The Assad coalition has not been shy about confirming the presence of such forces in Syria and Aleppo. In August 2016, a Nujaba Front spokesperson announced the deployment of 2,000 troops to the frontlines of southern Aleppo to bolster Assad’s position in the city. Iranian and pro-Assad media spread this message and released propaganda videos showcasing the militia’s presence in the city. Nujaba also linked their presence to Hezbollah, saying they fought alongside them.
After the fall of east Aleppo, al-Nujaba leader Akram al-Kaabi openly met with Iranian Supreme Leader Ali Khamenei to laud their victory. al-Kaabi is also known to have met several times with Hezbollah leader Hassan Nasrallah.
Hezbollah was extremely active in the siege of Aleppo, being credited as one of the first Iranian proxies to be involved. Early on in 2013, Lebanese Hezbollah forces numbered around 2,000 in Aleppo and were often on the front line in offenses against opposition forces in the city. Lebanese sources say that 1,600 Hezbollah fighters had died throughout Syria before Aleppo fell.
In many cases, regime forces credited Hezbollah efforts for winning key battles in the siege of Aleppo. During one of the last attempts to break the siege in October 2016, opposition forces launched a series of suicide car and truck attacks against the western flank of government-held west Aleppo. The attacks scattered the SAA, but Hezbollah elements managed to halt the offensive before they could inflict severe damage, maintaining the siege that eventually led to Assad’s victory.
As late as November 2016, there was evidence of senior Hezbollah activity in Aleppo through social media accounts that began circulating a picture allegedly of Hassan Nasrallah’s bodyguard being taken on the front lines of the siege in Aleppo.

In the final days of the battle for Aleppo, Hezbollah continued to be present, allegedly disrupting evacuation attempts by detaining people along the routes. Munir al Sayal, the head of the political wing of the Ahrar al Sham opposition group, claimed that Iran was refusing to honor the evacuation agreements until two Shia villages were offered relief. Under the instruction of Iran, Hezbollah detained hundreds of evacuees, leading to a number of reported deaths and the suspension of evacuation efforts.
Opposition sources said that during the final months of the siege of east Aleppo, not a single prisoner captured by the defending forces was a Syrian soldier. The militia’s presence lasted until the final hours of the siege. The UN Office of the High Commissioner for Human Rights said it collected reports of the execution of eighty-two civilians in several of the captured districts of the city, an act that was attributed to the militias, rather than the Syrian army or Russian forces.
After the fall of Aleppo, Iranian military leaders claimed victory, with Ali Khamenei’s chief military aide going so far as to say that Assad’s forces would not have been successful without Iranian support.
Russian Involvement
Russian involvement, while not as heavy on the ground, was arguably the most vital factor in securing Assad’s position in broader Syria, and Aleppo specifically, after its direct military intervention (originally described as a campaign against the Islamic State terrorist group) in September 2015. Russia launched over 15,000 airstrikes with an assortment of thirty-forty active aircraft, forty helicopters, and support from naval vessels, most visibly, the aircraft carrier Admiral Kuznetsov.
The strikes served to prop up pro-government forces in positions of weakness throughout Syria, and especially in Aleppo, before ground offensives were undertaken. Many strikes targeted aid infrastructure such as hospitals, and worked to undermine opposition defenses in besieged areas. Civilian casualties due to Russia’s airstrikes are estimated at 4,000, within fifteen months of intervention, significantly more than the number of Islamic State casualties caused by Russian airstrikes. By comparison, civilian casualties caused by the US-led coalition, in a campaign that has lasted since August 2014 and conducted over 17,500 airstrikes, are estimated at around 1,000.
Russia’s involvement on the ground has been limited compared to Iran’s. However, an estimated 4,000 Russian military personnel are believed to be operating in the country. One piece of evidence for this estimate comes from voting figures in the September Russian State Duma elections. Russia’s Central Election Commission released data after the election showing that 4,751 Russian citizens had voted from Syria, the majority coming from Russia’s Hmeimim military base. As of the end of 2016, twenty-three Russian soldiers had been confirmed dead in Syria.
The involvement of Russian special forces on the ground was also revealed by a series of videos shown on Russian TV detailing their operations, the first such evidence since special forces involvement was acknowledged in March 2016. Some of the footage was geolocated to reveal the operating position of the troops in an offensive on the town of Hakoura in the north of the al-Ghab Plain in Hama Governorate.



More recently, reports have surfaced detailing the alleged presence of Chechen special forces/police in Aleppo.


Opposition Forces
Opposition forces, while mainly made up of Syrian nationals, also consist of a variety of splintered militia groups from across the ideological spectrum. One of the most controversial aspects of the opposition presence in east Aleppo, was the presence of Jabhat Fateh al-Sham (JFS), previously known as the Nusra Front. The group was the official Syrian branch of al-Qaeda until it splintered from its parent organization in 2016, claiming autonomy in the region. They are, however, still widely considered to be al-Qaeda-linked and a terrorist, or terrorist-affiliated group.
JFS is estimated at 20,000 fighters strong, positioning itself as a significant force. Further complicating matters is the fact that JFS belongs to an alliance of roughly ten other opposition groups in Syria called Army of Conquest or Jaysh al-Fatah. Their combined strength has been estimated at 50,000, with JFS and Ahrar al-Sham, another Islamist group, composing 90 percent of the alliance.
The Army of Conquest often coordinated with more moderate opposition groups such as the Free Syrian Army, which primarily consisted of army defectors rebelling against the regime. JFS’s presence in Aleppo and Idlib, and Syria more broadly, is one of the complicating factors around the supply of US and allied equipment to opposition groups. The presence of JFS in the siege of Aleppo, raised questions over the nature of the opposition within the city, and with those who chose to stay in east Aleppo as pro-Assad forces lambasted those who chose to remain aligned with terrorists.
At the start of the conflict, the JFS grew quickly due to the opportunity that instability presented; at the start of 2012 they made up 1 percent of the overall opposition; by the end of the year, they made up 9 percent. In eastern Aleppo, however, their numbers remained small compared to overall opposition forces. Specifically, JSF had an estimated 2,000 fighters in Aleppo at the end of 2012 compared to 15,000 in the overall patchwork of armed opposition groups, and they ended with fewer than 1,000 besieged combatants in the final months and weeks, while other armed opposition fighters totaled roughly 8,000 combatants.