The Syrian Democratic Forces, Detained Foreign Fighters, and International Security Vulnerabilities


| Oct 24, 2022

Foreign fighters

Three-and-a-half years since the United States, its coalition partners, and the Syrian Democratic Forces (SDF) overpowered the last redoubt of the Islamic State of Iraq and Syria (ISIS), nearly 10,000 fighters remain in SDF custody in northeast Syria. These include approximately 5,000 Syrian fighters, 3,000 Iraqi fighters, and 2,000 foreign fighters. They are joined by about 60,000 mostly women and children, in desperate and deteriorating “closed” displaced persons camps under the care of the SDF and related militia. Ten-thousand of those are neither Syrian nor Iraqi. The continuing presence of the foreign fighters and their associated family members highlights a gap in international legal regulation peculiar to their circumstances: international law does not require countries of origin to accept the repatriation of nationals detained or displaced in non-international armed conflicts abroad.

In general, and excepting their progeny born in the region, the foreign fighters and family members in the custody or care of the SDF traveled to (or were trafficked to) Syria or Iraq to fight for, support, or live within ISIS’s territorial caliphate. They entered SDF custody or care as the caliphate collapsed in 2019. And, despite both the SDF’s pleas and the United States’ substantial efforts to encourage repatriation through diplomatic, exemplary, and policy approaches, progress has been remarkably slow. Indeed, many of the more than 50 States of origin whose nationals traveled to the conflict zone in the most substantial numbers have either refused to repatriate their fighters at all or simply failed, in recent years, to do so.  (Notably, in recent weeks, public reporting has revealed that both the Netherlands and Australia intend to repatriate significant numbers of their displaced—but not their detained—nationals from northeast Syria.)

Countries of origin cite a variety of reasons to excuse their failure to repatriate their nationals from northeast Syria. Among others, domestic security concerns, supposed lack of judicial or prosecutorial capacity, and an absence of rehabilitation or reintegration programs have figured prominently. Whatever the validity of these claims in individual cases, at bottom they reflect an international legal regime that leaves the repatriation of nationals caught up in a non-international armed conflict (NIAC) abroad discretionary. Thus, States of origin are free to address domestic political resistance and international security challenges according to their momentary national interests. That, however, leaves the international community with a general security challenge and a collective action problem.

Northeast Syria

The continued detention of thousands of fighters in northeast Syria, and the continued dislocation of tens of thousands of mostly women and children there, pose substantial and growing threats to international security. Many of those in SDF-operated detention facilities are likely experienced fighters, a subset of whom are committed members of ISIS. These fighters present an obvious and immediate threat to local, regional, and international security. Fighters escaping SDF custody might rejoin ISIS in the region or elsewhere, contributing to ISIS’ efforts at local resurgence or exacerbating ongoing conflicts.  Indeed, ISIS’s own history warns of this prospect. They might become a new generation of road warriors, traveling to emerging conflict zones. Or they may travel surreptitiously to their states of origin. By detaining them, the SDF provides the international community with a valuable but fleeting security good.

The SDF’s non-state status and uncertain future make it a poor substitute for the States of origin who should be responsible for detained foreign fighters. The SDF lacks the governance and security capacity of a sovereign State. It is incapable of conducting trials or effecting long-term, penal detention following convictions. (To say nothing of the practical questions raised by acquittals, which would almost certainly occur in at least some cases if such trials were fair.) Its predominately makeshift detention facilities are under threat of ISIS attacks and prison breaks. Even if its detention facilities were purpose-built and presumably more secure, the long history of unrecognized de facto authorities (see here and here) suggests that the SDF will eventually lose control of the area, its detention facilities, and the captured fighters in its custody. To make matters worse, the SDF could face renewed Turkish military action that would likely draw resources and attention away from its detention efforts, increasing the likelihood of escapes.

Perhaps even more worryingly, tens of thousands of women and children continue to reside in “closed” displaced persons camps. The humanitarian situation in these camps is abominable and getting worse. As much as two-thirds of the displaced population is under the age of 18 and half—approximately 30,000—are under the age of 12. These children are coming of age exposed to significant, destabilizing violence in an environment devoid of education, opportunity, or hope. Many of them are exposed to ISIS’s ideology and are vulnerable to recruitment or radicalization to violence. The longer they remain in that milieu, the more likely they are to pose a long-term—even generational—international security threat.

Ultimately, the only way to mitigate the foregoing security vulnerabilities is to repatriate the detained and displaced populations. Repatriation is also likely to significantly improve the humanitarian situation in displaced persons camps, which are overcrowded and strain both the SDF’s and humanitarian actors’ limited resources for the alleviation of the conditions there.  That, of course, cannot be accomplished without the repatriation or return of Iraqi and Syrian nationals. But neither can it be accomplished without the repatriation of non-Syrian and non-Iraqi nationals.

A Country-of-Origin Repatriation Obligation?

The challenge posed by the unwillingness of countries of origin to repatriate their nationals from northeast Syria arises because the foreign fighters and associated family members who remain in northeast Syria fall within an unfortunate lacuna of international legal regulation. The fighters in SDF custody were detained in the context of a NIAC with ISIS. The family members who reside in displaced persons camps were likewise dislocated in the context of the same armed conflict. The underlying armed-conflict nexus suggests that the law of armed conflict (LOAC) might establish rules concerning the protection and repatriation of foreign nationals deprived of their liberty in the course of a NIAC. But it fails to address these circumstances.

In the context of international armed conflict (IAC), express repatriation obligations exist under the law of armed conflict and fall primarily on detaining powers. For example, Article 118 of the Third Geneva Convention (GC III) requires detaining powers to repatriate prisoners of war (POWs) without delay upon the cessation of hostilities. It also requires them to repatriate seriously sick or seriously wounded POWs during the pendency of an IAC. While GC III does not explicitly require a country of origin to accept its nationals, that obligation is implicit. It is difficult to foresee how, practically, a detaining power might satisfy its obligation to repatriate POWs without the cooperation of the POWs’ country of origin. Moreover, Article 118 of GC III anticipates the detaining power and POWs’ country of origin agreeing to a plan to effect POWs’ return. Likewise, Article 118 requires that the detaining power and the repatriating country share the burden of repatriation. Finally, the International Committee of the Red Cross’s updated Commentary to the Third Geneva Convention notes that “one [State] must allow another to comply with its obligations under the Convention, and the [State] on which the prisoners depend must thus facilitate the repatriation of seriously wounded or sick prisoners of war and receive them.” (para. 4270)

The Fourth Geneva Convention (GC IV) similarly obligates interning powers to repatriate foreign nationals interned consequent to an armed conflict. Under Articles 41 and 42 of GC IV, States may intern civilians, including foreign nationals, if doing so is absolutely necessary.  Internment is permissible in such circumstances subject to regular procedures for deciding upon internment, rights of appeal, and periodic review. Nevertheless, internees must be released “as soon as the reasons which necessitated [their] internment no longer exist.” (GC IV, art. 132) Moreover, it is incumbent upon the parties to a conflict to endeavor to “conclude agreements for . . . the repatriation . . . of certain classes of internees, in particular children, pregnant women and mothers with infants and young children, wounded and sick, and internees who have been detained for a long time.” (GC IV, art. 132). In any event, Article 134 of GC IV requires that detaining powers, “upon the close of hostilities or occupation, . . . to facilitate [the] repatriation [of foreign internees].”

Together, GCs III and IV at least imply a reasonably complete regime for returning combatants and civilians deprived of their liberty consequent to an IAC. Of course, the panoply of the Conventions applies only to IACs. Notwithstanding the increasing convergence of the law of armed conflict governing IACs and NIACs through customary international law, the regulation of non-international armed conflict, particularly concerning detention, remains underdeveloped.

This fact may be especially true in the context of NIACs that involve substantial numbers of foreign fighters. The lex scripta of LOAC applicable to NIACs is silent on repatriation. Common Article 3 makes no mention of it. Neither do any provisions of Additional Protocol II.  Nevertheless, it is widely recognized that conflict-based detention in NIACs must end with the termination of the relevant conflict—just as it does in IACs—lest that detention become arbitrary and unlawful. It is reasonable, therefore, to infer that the post-conflict obligation to release NIAC-based detainees also implicates a post-conflict obligation to repatriate foreign fighters and their family members detained in the course of a NIAC. The repatriation regimes for both combatants and civilians found in GC III and GC IV bolster the claim, as do the equivalent rules under customary international humanitarian law as identified by the International Committee of the Red Cross 2005 survey.

A separate but closely related question concerns any potential obligation to repatriate foreign fighters and their family members while a NIAC persists. It is worth recalling, again, that the legality of continued detention in a NIAC is called into question once the reasons justifying such detention abate. Thus, when a detaining power determines that a foreign fighter’s detention is no longer necessary, the fighter’s continued detention may become arbitrary and illegal. Similarly, analogical application of the law governing IACs to NIACs in order to fill gaps found in the LOAC regulation of NIACs may suggest that at least detained fighters who are seriously sick or seriously wounded should be repatriated during an ongoing armed conflict.

Significantly, however, foreign fighters who voluntarily traveled to a conflict zone to participate in a NIAC challenge analogical application of the GC III repatriation regime in a critical respect.  In an IAC, POWs find themselves in the hands of the enemy consequent to their participation in an armed conflict at the behest and to the benefit of the State on whose part they fought. They are affiliated with and, typically, owe allegiance to that State. And their State of allegiance is presumed to have  a material interest in their repatriation. Foreign fighters detained in the course of a NIAC may not enjoy a similar relationship with their State of nationality, which may in part explain the lack of vigor so many countries of origin evidence in repatriating them from northeast Syria.

Analogical application of GC IV may be less troublesome. It may indicate that wounded, sick, and pregnant individuals in “closed” displaced persons camps, as well as mothers with infants or young children, be treated as interned and should be repatriated. In the absence of an obligation on the part of their country of origin to accept repatriation, the detaining power would be placed in an untenable position where these individuals must be kept in its custody without legal authority or in contravention of LOAC.

Aside from LOAC, neither international human rights law nor refugee law impose a clear obligation on the part of countries of origin to repatriate their nationals from northeast Syria. For example, individuals’ right of return does not carry with it an affirmative obligation on the part of their country of nationality to affect their return. Indeed, no international human rights instrument appears to require a country of origin to repatriate its nationals in circumstances like those trapped in northeast Syria—with the possible exception of children based on their best interests.

Concluding Thoughts

The regulatory gap exposed by the refusal or failure of countries of origin to repatriate their nationals from the custody or care of the SDF calls out to be filled. The absence of legal obligation makes repatriation discretionary. It puts governments in the position of choosing between near-term domestic political imperatives and long-term international security challenges. Together, these have left the international community with a collective action problem in general, as well as a potentially global and generational security vulnerability in the specific case of northeast Syria. But law that clearly establishes the circumstances under which countries of origin must repatriate their nationals would help resolve that collective action problem by eliminating the choice to repatriate or not, impeding the recurrence of this type of problem. Despite the substantial political difficulties of establishing a comprehensive regime for NIACs, perhaps it is time to revisit the treaty-based governance of non-international armed conflicts to clearly assigns rights and duties to parties and non-parties alike.


Benjamin R. Farley is a Visiting Professor at Emory University School of Law and the Acting Director of the Emory International Humanitarian Law Clinic. He is on leave from the U.S. Department of State, where he serves as Deputy Director of the Office of Terrorist Detentions in the Bureau of Counterterrorism. The views expressed do not represent the views of the U.S. Department of State.


Photo credit: Mirwais Bezhan