Eurasia Press & News
This paper examines the complex situation of foreign fighters in Syria after the change of the former regime, details their composition, explores the long-term challenges and risks arising from their integration into the new Syrian army, their leadership roles, and the consequences of this locally and internationally, and addresses the issue of thousands of foreign fighters detained from ISIS. It reviews the future scenarios of these fighters, whether those involved in the structures of the new state, or ISIS detainees with the Syrian Democratic Forces.
The security and military aspects in Syria witnessed a radical transformation after the regime change in December 2024, one of the features of which was the rise of foreign fighters who participated with the armed opposition forces in the fight locally against the forces of the former regime after 2011, and their integration into the security structures of the new authority, which provoked a number of local and international reactions of multiple aspects, amid fears of the regional and international security repercussions caused by the activities and movements of these fighters. This paper assesses the complex situation of these fighters, details their composition, explores the long-term challenges and risks arising from their presence, and addresses the issue of thousands of foreign fighters detained from ISIS, which continues to pose a significant threat to instability in the region and beyond.
The spectacle of foreign fighters in Syria
Estimates of the number of foreign fighters involved in the Syrian crisis (2011–2024) vary widely, but generally range from 40,000 to more than 60,000 fighters from more than 100 countries during the peak years of the crisis (2013–2017), as the flow of foreign fighters to Syria fluctuated over time, and the period coinciding with the rise of the terrorist organization ISIS between 2014-2016 saw a peak in numbers.
First, between 2013 and 2015, the U.S. military reported an average of 2,000 foreign fighters arriving in Syria and Iraq per month, and in December 2013, the International Center for the Study of Extremism estimated that up to 11,000 individuals had joined the armed opposition in Syria, and by January 2014, then-U.S. Director of National Intelligence James Clapper estimated the presence of more than 7,000 foreign fighters in Syria on the rebel side alone.
Second, between 2016-2018, that rate slowed markedly, falling to less than 500 fighters per month in 2016, and continued to decline due to battlefield losses and international countermeasures. By 2018, Syrians made up the majority of fighters in armed opposition groups.
In fact, the motives of foreign fighters involved in the crisis differed, but most of them were motivated by radical Salafist ideology. The largest groups of foreign fighters came from the Middle East and North Africa, especially Tunisia (about 6000), Saudi Arabia (2500), Turkey (2100) and Jordan (more than 2000), while Western Europe contributed about 5,000 fighters, mostly from France, Germany, the United Kingdom, Belgium and Sweden, and from Russia participated about (2400), and other prominent sources included the republics of the former Soviet Union (4700), Southeast Asia (900), the Balkans (875), and North America (289). They were divided among multiple groups, including ISIS, Jabhat al-Nusra (later Hay’at Tahrir al-Sham), al-Qaeda (later Hurras al-Din), and other armed and extremist Salafist groups.
However, the situation of foreign fighters in Syria is not limited to opposition forces, especially after the crisis has acquired a regional and international character, as Iran has rushed to support the former regime with Iranian fighters and from other countries, such as the participation of Iraqi armed factions and Lebanese Hezbollah, and from Pakistani and Afghan fighters, such as the Fatemiyoun Brigade, which began its activity before expanding to become a brigade in 2015. Overall, the number of pro-Iranian fighters in Syria has increased significantly as its influence deepens there, rising from about 10,000 in 2013 to 15-25 thousand by 2016, according to the Financial Times at the time. But these fighters left Syria with regime change, and in conjunction with the withdrawal of the Iranian Revolutionary Guards.
On the other hand, while the percentage of foreign fighters among armed opposition groups has decreased since 2018, those who remain, especially among the factions loyal to HTS, played a role in the recent attack that led to the collapse of the former regime’s forces. In contrast, a large number of foreign individuals who have joined ISIS remain in detention, primarily held by the Syrian Democratic Forces (SDF) in northeast Syria, and it is estimated that some 8200 foreign ISIS terrorists are currently in the grip of the SDF, while their families are being held in camps such as al-Hol and al-Rouj. This separate gathering of foreign fighters, who are not allied with the new government, poses a significant and ongoing security challenge to the region, and the existence of these camps is a complex humanitarian situation, with long-standing fears of increased radicalization of individuals detained there.
Integration into the new Syrian regime
A number of foreign fighting groups allied with Hay’at Tahrir al-Sham remained after the change of the former regime in Syria, and although there is no accurate estimate of the number of foreign fighters remaining, the most prominent of these groups include the Turkistan Islamic Party, which is estimated to have about 2,500 fighters; the supporters of the unification, which includes about 200 fighters; the Caucasus, which has about 250 fighters; and the Chechen Ajnad al-Sham group, which includes about 300 fighters. With the formation of the new Syrian Army, these fighters were integrated into official military formations and under the unified command structure, where independent foreign fighters groups were dismantled and their members were formally included in the Syrian army. Syrian President Ahmed al-Shara’a focused on the large contributions of these foreign fighters to the overthrow of the former regime, pointing out that those who contributed to “the overthrow of Assad deserve the reward,” and hinted at the possibility of granting them Syrian citizenship in exchange for their efforts.
In theory, there are historical precedents for prominent roles played by foreign fighters in various national armies, and the most prominent examples include the French Foreign Legion, which has a long history of integrating foreign nationals, as well as the integration of foreign-born soldiers in the American Civil War, and the participation of foreign fighters in the Spanish Civil War in the 1930s alongside Republicans against the nationalists led by General Franco. In the contemporary context, Ukraine faces a similarly complex model, as foreign corps fights alongside the Ukrainian army against Russian forces since the outbreak of the war in the spring of 2022, including the International Regional Defense Corps of Ukraine, which includes Poles, French and Georgians, where Russia estimates the number of fighters at about 18,000 fighters from 85 countries around the world.
These historical and current models are a central part of the Syrian Interim Government’s attempts to legitimize foreign fighters in the opposition and toward their integration into the Syrian army. However, the specific geopolitical motives, ideologies and repercussions of these historical examples may differ greatly from the current situation in Syria, and therefore the opinion is strongly divided among Syrians, between those who consider their integration an expression of the new authority’s gratitude to these foreign fighters, and those who saw it as clear pragmatism, as these are a force that can be used in the future if needed, and those who considered that the authority has no other option, because their non-containment threatens to pose a great threat to the emerging and fragile stability in the country. This integration has not been accepted by another stream of Syrians, due to various factors, such as concerns about the long-term loyalty of these fighters, the possibility of pursuing agendas that are incompatible with national interests, as well as concerns among minorities in Syria of the militancy shown by foreigners, and the higher level of violence attributed to them.
In addition, the problem of foreign fighters is linked to the balance of power within the opposition armed factions and their alliances, where a number of Syrians who participated in the fighting feel marginalized because of the importance given to foreign elements, especially towards the influence of these foreign fighters, some of whom have obtained key leadership positions, according to media reports, about 50 of them were assigned to leadership positions, including six in senior positions within the intelligence service, the army and the Republican Guard, and among the most prominent appointments, Abdul Rahman Hussein Al-Khatib, a Jordanian with the rank of brigadier general, was appointed commander of the Republican Guard, in addition to assigning about 50 other commanders, including Abdul Bashari, Omar Mohammed Jafchi, and Egyptian Alaa Mohammed Abdul Baqi, in addition to Abdul Aziz Daoud Khadabardi, who belongs to the Turkistan minority in China. At the international level, the integration of foreign fighters, especially those with well-known Salafist extremist affiliations, has raised great concern among Western governments, and Washington has called on the Syrian government to remove foreign fighters, and to stop granting these foreign fighters sensitive government positions.
Challenges and concerns about foreign fighters
The main challenge is that foreign fighters can destabilize the region or pose a threat to international security, especially given the ideological affiliations of many of them, and it is feared that individuals with a history of engaging in extremist groups will exploit their positions of power within the new Syrian government to serve their ideological agendas, which may turn Syria into a springboard for attacks on neighboring countries or the West, especially at a time when Syria still faces various security threats, some of which result from existing terrorist groups such as ISIS, and a number of competing armed groups that may not be fully integrated into the new military structure.
The presence of foreign fighters within the government would complicate these threats, as the loyalties and priorities of these foreign elements may not always correspond to Syria’s broader national security interests. Moreover, a number of them may oppose the interim government’s foreign policy of openness to relations with the United States and its willingness to consider normalization with Israel. Given the limited options of these fighters and their decline inside Syria, with their countries unwilling to receive them, this means that they have two options: either to rebel against the government, or to join terrorist organizations such as the Guardians of Religion and ISIS. In May 2025, the latter, through his newspaper Al-Naba, called on foreign fighters in the Ministry of Defense to join his cells, considering that the new authority is using them to serve its project. His call included those dissatisfied fighters in Hay’at Tahrir al-Sham, a number of whom have tended to defect and join factions outside the Defense Ministry, including the Ansar al-Sunna Brigades, which adopts a similar approach to ISIS.
On the other hand, there are fears behind these fighters about their involvement in reprisal violence, especially those some of whom have participated in previous violations or have a history of working outside the law, and there have been multiple reports of the involvement of foreign fighters in the violations committed in the events of the coast during a government military operation in March 2025. This highlights the complexities that the integration of these fighters brings to reconciliation efforts, especially in light of the long history of social and sectarian complexities in the Syrian situation, in light of the years of crisis that have deepened these divisions, and the dominant feature towards foreign fighters as biased towards certain groups or some of them have participated in sectarian violence..
The issue of detainees and foreign suspects from ISIS and their families currently detained in northeast Syria poses a major and complex challenge to the international community, nearly six years after the collapse of the so-called “caliphate” in 2018, the detention of about 26,000 foreign people continues. Recent leadership changes in both Washington, D.C., and Damascus have provided a potential, albeit narrow, opportunity to address this chronic issue, and Syrian President Ahmed al-Shara’ could play a role in energizing efforts to resolve the issue, especially in light of his political and military agreement with the Kurds in northeast Syria, which still enjoys a kind of autonomy.
Despite the continued call of the United States for all countries to return their citizens from camps such as al-Hol and al-Ruj, stressing that these camps serve as incubators of terrorism, which may lead to further extremism for another generation, many countries have shown their reluctance to take back their citizens who joined ISIS, as a result of security concerns, legal complications related to the prosecution of individuals for crimes committed in a foreign country, and domestic political considerations. Western security services have long expressed concerns that foreign fighters returning to their countries of origin may pose a significant terrorist threat, by acquiring high combat skills, establishing ties with international terrorist networks, and increasing their level of radicalization during their time in Syria, where the concern is that they can use these experiences to plan and carry out terrorist attacks in their countries of origin or in other countries, and this threat is exacerbated by the induction of some extremist Salafist groups in the West to carry out such attacks.
In doing so, these countries have adopted different methods of dealing with their foreign fighters; some have chosen to return their citizens to their homelands for trial within their legal systems, while other countries have tried to prevent the return of their citizens by stripping them of their citizenship or by challenging the validity of their nationality, while the third approach was to avoid facilitating the return of foreign fighters, which basically means leaving them in the custody of the Syrian Democratic Forces or other entities in Syria. At the same time, the absence of a unified international strategy on this issue has contributed to the continued detention of these foreign fighters and their families, and to the serious situation in which they live. The fate of databases and intelligence on these foreign fighters is also an additional challenge, along with the difficulty of distinguishing between individuals who pose a real security threat and those who have been victims of or forced to join ISIS, complicating decision-making regarding the transfer of detainees or the sharing of intelligence
In general, the presence of a large number of foreign fighters in Syria, especially those with extremist ideologies and combat experience, carries with it a great danger in its territorial and international reach; some Chechen fighters, who were previously active in northwestern Syria, have already participated in the conflict in Ukraine, which highlights the readiness of some of these individuals to deploy in different conflict areas whenever they have the opportunity. The combat experience gained in the Syrian crisis, along with the extremist ideologies of many of these fighters, makes them ready and able to engage in other conflicts or carry out terrorist acts in their countries of origin or in other regions of the world.
Scenarios of foreign fighters in Syria
The file of foreign fighters in Syria is divided into two main categories based on their current situation: the fighters involved in the structures of the new state, and the detainees of the organization “Daash” with the Syrian Democratic Forces. In fact, the scenarios for each category are different.
أولاًFirst: Scenarios of the fighters of the factions within the “Hayat Tahrir al-Sham”
First scenario: Settlement and full integration
This scenario is a continuation of the current trend initiated by the new Syrian authority. It includes granting foreign fighters Syrian citizenship and enabling them to continue to hold leadership positions in the army and security services. This scenario is reinforced by several factors, including the interim government’s need for a loyal military force to support its authority, the willingness to reward these fighters for their role during the crisis, and the fear of their insurgency if they are excluded.
However, this scenario faces many challenges, foremost of which is international pressure, especially from Western countries, which have set the condition of stopping granting foreign fighters senior positions in the state in exchange for openness and the sustainability of the lifting of sanctions on the country, in addition to local fears of the multiple loyalties of these fighters and their potential jihadi agendas, especially in light of the possibility of exacerbating sectarian tensions, especially with the involvement of some of them in violations against minorities in the Syrian coast in particular.
Scenario II: Progressive demobilization
This scenario represents a compromise for the interim government to respond to international pressure on the one hand, and to prevent foreign fighters from turning against it on the other. This scenario involves the gradual demobilization of foreign fighters from sensitive government and military positions, and their replacement by Syrian cadres, with the possibility of integrating them into civilian sectors or providing incentives for their voluntary departure.
The possibility of applying this scenario increases with the escalation of international pressure on the government, and the escalation of popular discontent with the roles of these fighters, and perhaps because of the escalation of their influence within the decision-making joints in the state, which is a source of negative impact on domestic and foreign policies. In fact, a number of foreign fighters have already left military activity and started their own business and trade, and there are many examples of this in Idlib, which makes the expansion of this model an option, especially if the government follows disciplined implementation mechanisms, including, for example, rehabilitation and reintegration programs into civil society, financial compensation for voluntary abandonment of military positions, and gradual retirement with the guarantee of certain privileges.
Third scenario: repatriation to the original
This scenario involves returning foreign fighters to their countries of origin, whether voluntarily or forcibly, under international pressure, or as part of bilateral deals with the countries concerned. In this context, there have been reports of arrest campaigns by the Syrian security services targeting foreign fighters (specifically from Arabs). Deportation may be the next step, especially for Arab fighters, as their return is easier than those whose countries refuse to take them back, due to security concerns or legal and political complications, or because their countries have already stripped them of their citizenship.
Scenario IV: Conflict and liquidation
This scenario refers to the possibility of an internal conflict between the different factions, or the liquidation of some foreign fighters on the orders of the new leadership. The likelihood of this scenario is increased as the current situation remains unchanged, as the continued integration of fighters with extremist ideologies into state structures could lead to growing extremism and deepening divisions between currents. This scenario could also occur if the PA takes decisions to address the phenomenon of foreign fighters in ways that do not satisfy them or exclude them from positions of influence sharply.
ثانياًSecond: Scenarios of ISIS detainees detained by the Syrian Democratic Forces
1- The scenario of repatriation: It includes the return of detainees to their countries of origin for trial there, which is called for by the United States on an ongoing basis, but it is met with the reluctance of a number of countries, especially European ones.
2- The local trial scenario: It includes the trial of ISIS detainees within the new Syrian judicial system, or through the establishment of a special international court that oversees their trial in Syria.
3- Rehabilitation and integration programs scenario: It includes the implementation of comprehensive programs to de-radicalize and rehabilitate low-risk detainees, in preparation for their reintegration into society or their return to their countries of origin.
4- The scenario of escape and the rise of ISIS again: It is the most dangerous scenario, and may be accompanied by any new security deterioration in Syria or the sudden withdrawal of international forces from the detention areas, which may lead to the mass escape of the elements of the organization and its re-formation.
Finally, the coming period is likely to witness a gradual approach that includes reducing the influence of foreign fighters in state structures under international pressure, with the implementation of rehabilitation and reintegration programs for the least dangerous elements, and the adoption of strict security measures to deal with the most extremist elements. As for ISIS detainees, international negotiations over their fate are likely to continue, with some of them likely to return home under limited bilateral agreements. In general, Syria is going through a complex and unstable phase, and foreign fighters remain a threat to the collision of ideologies, and a constant warning of the possibility of the return of extremism and terrorism, whether through ISIS or other organizations that may arise in the future.
