Analyzing State Support to Non-State Actors – Part I: Primary Obligations and Attribution
Today, armed conflicts are frequently characterized by State support to non-State actors as a means of advancing the former’s strategic objectives. For instance, Iran continues to enable Hezbollah, Hamas, Houthi, and other militia operations throughout the Middle East (see, e.g., here, here, and here). And until recently, Russia made extensive use of a private military company, the Wagner Group, to pursue its foreign policy aims in Africa, the Middle East, and Ukraine until the Group fell from grace following an attempted coup by its leader and its subsequent absorption into Russian government structures (see, e.g., here, here and here). The United States has likewise engaged with non-State actors in its ongoing support to the Syrian Democratic Forces operating in northeast Syria (see, e.g., here, here, and here).
This practice is by no means new. Historical examples abound, especially during the Cold War. Indeed, the seminal International Court of Justice (ICJ) case concerning State support to non-State actors, Paramilitary Activities (1986), directly addressed the United States’ support to the Contras, an “organized armed group” (OAG). Despite the prevalence of this practice, legal analysis remains challenging, as the relationship between the State, its support, and the non-State actors is often opaque. Further complicating matters is the law itself, a confusing tapestry of legal regimes and concepts.
In this two-part series, we seek to address the latter challenge by providing a normative framework for analyzing one State’s support to non-State actors engaged in hostile activities directed at another. We consider both “active” and “passive” support. As used in this post, the former refers to situations in which a State affirmatively provides support to the non-State actor, such as finances, material, intelligence, and other resources that enable it to conduct its operations. The latter denotes a State’s inaction, such as permitting a non-State actor to conduct hostile operations from territory under the State’s control.
To do so, we survey the international law applicable to four distinct questions. First, we examine whether the support given by a State to a non-State actor, either actively or passively, violates any primary rules of international law. We then turn to when a State is responsible under the law of State responsibility for the actions of a non-State actor. Having examined whether State support amounts to an internationally wrongful act, we next outline the responses available to the victim State. Finally, we address the question of when State support to a non-State actor engaged in hostilities with another State triggers an international armed conflict (IAC) between the two States. In this installment of our two-part series, we address the first two questions: violations of primary obligations; and attribution.
Violations of Primary Rules of International Law
The first question regarding State support of non-State actors is whether the support—active or passive—violates a “primary rule” of international law. Violations of international law require both the breach of an obligation owed to another State and legal attribution to the State engaging in that act, which may consist of an action or omission (Articles on State Responsibility (ASR), art. 2). In other words, these are situations in which the State’s own conduct, rather than that of the non-State actor, amounts to an “internationally wrongful act.”
The law of State responsibility sets forth numerous bases for legal attribution of conduct to a State, the most common being that which attaches when an “organ” of the State engages in an act breaching an international law rule. The UN International Law Commission (ILC) has recognized this customary law basis for attribution in Article 4 of its Articles on State Responsibility.
All government employees and organizations are de jure organs of the State, and the State is legally responsible for their actions, even when those actions are ultra vires, conducted without authorization or even in violation of the State’s express instruction (ASR, art. 7). Individuals or entities that operate in “complete dependence” on the State are also organs of that State. As noted by the ICJ in the 2007 Bosnian Genocide case,
Persons, groups of persons or entities may, for purposes of international responsibility, be equated with State organs even if that status does not follow from internal law, provided that in fact the persons, groups or entities act in ‘complete dependence’ on the State, of which they are ultimately merely the instrument (para. 392).
In other words, States shoulder responsibility for the actions or omissions of de facto State organs. Assuming attribution on this basis, the question becomes: which rules of international law prohibit support to a non-State actor? There are four of particular significance.
Respect and Ensure Respect
Common Article 1 of the four 1949 Geneva Conventions provides that parties to those instruments “undertake to respect and to ensure respect” for the Convention’s provisions “in all circumstances.” It is widely accepted that this article reflects customary international law in international armed conflict (IAC) (see, e.g., Paramilitary Activities, para. 220). The scope of the article has been the source of significant controversy (see, e.g., Schmitt & Watts; Zwanenburg).
In the view of some, the issue with respect to common Article 1 is attribution. By this approach, the wrongfulness of a State’s support to a non-State group acting in violation of the law of armed conflict (LOAC) depends on whether the actions are attributable under the law of State responsibility (see below). For instance, the U.S. Department of Defense (DoD), Law of War Manual takes the position that common Article 1 “does not reflect an obligation to ensure implementation of the Conventions by other States or parties to a conflict” (§ 18.1.2.1).
In our view, however, common Article 1 is a primary rule of international law that does not depend upon attribution of the non-State actor’s violation to the State. This rule is in two parts. The “respect” obligation bars States from knowingly supporting a group that uses that support to violate LOAC. Moreover, in its Paramilitary Activities judgment, the ICJ found that “the United States [was] thus under an obligation not to encourage persons or groups engaged in the conflict in Nicaragua to act in violation of the provisions of Article 3 common to the four 1949 Geneva Conventions.” In our estimation, this would mean the respect obligation likewise bars the provision of any significant support to a non-State group engaging in systematic violations of LOAC. For instance, Iran’s provision of arms to Hamas that Hamas then uses for systematic attacks on the Israeli civilian population is unlawful on this basis. So too is other support making possible Hamas’s frequent attacks on civilians (see, e.g., here and here).
By contrast, the “ensure respect” obligation requires a State to ensure that individuals or non-State actors operating from territory under the State’s control comply with LOAC. Accordingly, a State providing support to a non-State actor operating from such territory must terminate that support if doing so will cause it to desist from further violations. The obligation would also apply to a State’s passive support, such as allowing the non-State actor to operate from its territory. In other words, a State does not have to provide active support to the non-State actor to trigger the “ensure respect” obligation.
Due Diligence
Whereas the “respect and ensure respect” obligation only applies in situations in which there is an armed conflict, general international law arguably imposes an analogous obligation of “due diligence” that applies at all times. An annex to a 2024 ILC report describes due diligence as the “duty or standard of care that should be applied to a State’s actions on its territory or activities subject to its jurisdiction or control, which harm the rights and interests of other States” (A/79/10, Annex II).
Notably, this obligation has been the subject of significant disagreement, particularly in the context of cyber operations. Some States take the position that it is a primary rule of customary international law, while others are only willing to ascribe non-binding status to it (see Schmitt; Jensen & Watts). In the latter case, States style due diligence as actions that responsible States should take but are not obligated to take as a matter of law. It is unclear how this debate manifests beyond the cyber context.
We are of the view, at least in the non-cyber context, that due diligence is a primary rule of international law. By the rule, States are obligated to take feasible measures to end ongoing operations from their territory that they know of and that seriously and adversely affect another State’s legal rights. In the context of this post, the issue is a State’s obligation to terminate from its territory hostile operations by a non-State actor against other States, and operations that support the non-State actor, when those operations implicate the right of another State to be free from the use of force (see below).
Note that the issue is not active support since that would likely violate other rules like intervention (see below). Rather, passive support in the form of at least acquiescing to the use of the State’s territory by the non-State actor breaches the obligation of due diligence. It is important to note that the due diligence obligation applies to any conduct that negatively affects the legal rights of another State (not just those resident in LOAC), as in the use of force case just mentioned. In that sense, it is broader than the “respect and ensure respect” obligation. There are circumstances where the failure of a State to take action would violate both rules.
But it also merits caution that the rule is rather limited. It only requires a State to take measures that are feasible in the circumstances to terminate harmful conduct by a non-State actor. Moreover, it does not require the State to monitor its territory to identify such conduct, nor take any action in anticipation of future actions by the non-State actor. Additionally, the obligation only attaches when the harm caused to the State against which the non-State actor is conducting its operations is significant and affects a legal right of that State. In the circumstances under consideration, the legal right that is most relevant is the State’s right to be free from the use of force against it.
Take a case in which a terrorist organization (an OAG) and State A are involved in NIAC. State B is turning a blind eye to the terrorists, who are conducting attacks from its territory against civilians in State A. Assuming State B can feasibly put an end to the terrorist group’s operations, it is our opinion that State B is likely violating both its obligation under Common Article 1 and the general principle of due diligence. However, if the terrorists are conducting operations that do not violate LOAC (e.g., attacks on military objectives), State B would not be in breach of the ensure respect obligation of Common Article 1. Still, the duty of due diligence would obligate State B to put an end to the terrorist group’s actions if doing so is feasible because they implicate the right of State A to be free from the use of force against it (see e.g. Tallinn Manual 2.0, rule 6, para. 21). This, of course, depends on whether due diligence qualifies as a rule of international law.
Intervention
Support to non-State actors can also violate the prohibition on intervention into the internal or external affairs of other States. Indeed, the ICJ’s lead case on intervention is the Paramilitary Activities case cited above, which involved State assistance to insurgents.
There, the ICJ characterized intervention as consisting of two elements. First, the action in question must bear on an area of activity by the other State that is reserved to that State in the sense that international law does not govern it. As noted by the Court, “prohibited intervention must accordingly be one bearing on matters in which each State is permitted, by the principle of State sovereignty to decide freely. One of these is the choice of a political, economic, social and cultural system, and the formulation of foreign policy” (Paramilitary Activities, para. 205). In most cases involving support to non-State actors conducting operations against another State, this criterion is satisfied because the operations’ goals typically involve a change in government or other significant domestic objectives.
The second criterion, which the Court labeled the “very essence” of prohibited intervention, is “coercion.” Coercion must be distinguished from mere influence, which does not constitute intervention. However, coercion is “not limited to physical force, but rather refers to an affirmative act designed to deprive another State of its freedom of choice, that is, to force that State to act in an involuntary manner or involuntarily refrain from acting in a particular way” (Tallinn Manual 2.0, rule 66, para. 18).
Supporting a non-State group engaging in hostilities against another State will almost always rise to the level of coercive action. As the ICJ noted in Paramilitary Activities, “support … to … military and paramilitary activities [of insurgents] by financial support, training, supply of weapons, intelligence and logistic support, constitutes a clear breach of the principle of non-intervention” (para. 242; see also Armed Activities, para. 164, confirming that military intervention may violate both the prohibition on intervention and the prohibition on the use of force). Thus, the question is when does support that qualifies as intervention also amount to a wrongful use of force?
Use of Force
Finally, in certain circumstances, a State’s support to a non-State actor constitutes a use of force in violation of Article 2(4) of the UN Charter and customary international law against the State that the non-State actor is fighting. In other words, when does the very act of providing support to a non-State actor amount to a wrongful use of force by the supporting State?
There are certain limited circumstances in which mere support to a non-State actor qualifies as a use of force. In Paramilitary Activities, for instance, the ICJ held that “arming and training” amounted to a use of force, distinguishing it from “the mere supply of funds.” The latter was mere intervention. Also significant is the UN General Assembly’s Friendly Relations Declaration, which was adopted by consensus (A/RES/2625 (XXV)). In addressing the prohibition on the use of force, it stated,
Every State has the duty to refrain from organizing, instigating, assisting or participating in acts of civil strife or terrorist acts in another State or acquiescing in organized activities within its territory directed towards the commission of such acts, when the acts referred to in the present paragraph involve a threat or use of force.
It is important to emphasize that such support is itself a use of force by the supporting State. This must be distinguished from situations in which a State is responsible for a non-State actor’s use of force pursuant to the attribution of that conduct to the State under the rules of State responsibility, as discussed in the next section.
One of the authors has examined the notion of “indirect force” in the context of aid to States engaged in an IAC. In his view and that of his co-author, “evolving approaches to the prohibition have embraced a more flexible, adaptive understanding of the notion of the use of force, one supported by the UN Charter’s text, travaux préparatoires, and subsequent interpretation and practice by States, and reinforced by the persuasive reasoning of the International Court of Justice.” Consequently, the authors conclude that “the use of force extends to indirect force, including some forms of aid or assistance to States engaged in forcible operations.” In assessing when indirect force would do so, they look to such factors as intent, timing, the degree to which the support directly impacted ongoing operations, the nature of the support, and its impact. The logic of their conclusions would apply analogously to State support to non-State actors. By this approach, the key is to look contextually at the support provided by the State.
Obviously, the line between support that amounts to mere intervention and that which also crosses the line into a use of force violation is unsettled. However, as a general matter, the greater the nexus to forcible actions by a non-State actor, the more likely the act of supporting will qualify as a use of force.
Attribution of Non-State Actor Acts
In the previous section, we addressed situations in which a State’s actions in providing active or passive support to a non-State actor violated a primary rule of international law. As discussed, the actions of State organs are always attributable to that State. However, supporting a non-State actor will sometimes render the supporting State responsible for that non-State actor’s actions.
In cases where a non-State actor engages in activities that would, if conducted by the supporting State, violate international law, the rules of attribution in the law of State responsibility determine whether the non-State actor’s actions or omissions can be attributed to the supporting State. This could be the case, for instance, if the non-State actor engages in actions that would qualify as a use of force in violation of Article 2(4) of the UN Charter and customary international law or when the non-State actor’s operations violate LOAC.
There are numerous bases for attributing a non-State actor’s conduct to a State. As noted earlier, these “secondary” rules of international law have been captured in the ILC’s restatement of the law of State responsibility, the ASR. They are, as a general matter, considered to reflect customary international law. For instance, Article 5 of the ASR provides that the acts of non-State actors that, having been “empowered by law,” “exercise elements of government authority” are attributable to the State that sanctioned them. And a State that “acknowledges and adopts” the conduct of a non-State actor will be likewise responsible in law for that conduct (ASR, art. 11).
However, in the vast majority of cases, the basis for attribution of a non-State actor’s acts is that the individual or group concerned “is in fact acting on the instructions of, or under the direction or control of, that state in carrying out the conduct” (ASR, art. 8). Although the ILC’s commentary on the article disaggregates the three bases, they are often characterized together as “effective control” over the non-State actor. In Paramilitary Activities, for instance, the Court assessed the actions of the United States in supporting the Contra guerillas in Nicaragua by asking whether it “had effective control of the military or paramilitary operations in the course of which the alleged violations [of LOAC by the Contras] were committed” (para. 115).
It must be understood that the threshold of “effective control” is high. As noted in Paramilitary Activities, (para. 115),
… participation, even if preponderant or decisive, in the financing, organizing, training, supplying and equipping of the contras, the selection of its military or paramilitary targets, and the planning of the whole of its operation, is still insufficient in itself … for the purpose of [attributing on the basis of effective control]…. [E]ven … general control … over a force with a high degree of dependency on it, would not in themselves mean, without further evidence, that the United States directed or enforced the perpetration of the acts contrary to human rights and humanitarian law.
In our view, this description sets the bar too high, allowing States to escape responsibility in cases in which responsibility should clearly attach. For instance, having a decisive voice in selecting targets or planning specific operations should be sufficient for the State to bear responsibility for the non-State actor’s LOAC violations.
But what is clear is that the mere fact of support to a non-State actor, even when the non-State actor is engaging in hostilities, does not suffice to trigger attribution. Instead, the support must reflect a significant degree of control over the group’s actions. The most likely case is when the State exercises meaningful command and control over the non-State actor’s military operations. Unfortunately, there is no bright-line test to determine when mere support, which may be unlawful as described in the previous section, reflects a degree of support sufficient to attribute the non-State actor’s acts to the State.
Unlike attribution of the actions of a State organ (or a non-State actor exercising elements of government authority after having been empowered by law to do so), attribution on the basis of instructions, direction, or control does not extend to ultra vires acts. In other words, a State will not be responsible for non-State actor actions contrary or unrelated to its instructions, direction, or control. Thus, even if a State is exercising command and control over a non-State actor, it will not be responsible for violations of LOAC when it previously instructed the group to comply with that body of law.
Conclusion
When analyzing State support to non-State actors, not only are the relevant facts typically muddied (sometimes deliberately so), but the relevant legal questions are also governed by separate and sometimes overlapping bodies of international law that are often conflated. These realities frustrate the effort to assess the State’s support reliably.
In Part I, we have introduced two aspects of the normative framework for governing State support to non-State actors, direct violation of primary rules and violation of those rules through attribution of the non-State actor’s conduct. In Part II, we complete our framework by outlining the responses available to victim States and addressing when State support to a non-State actor triggers an IAC between the two States.
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Michael N. Schmitt is the G. Norman Lieber Distinguished Scholar at the United States Military Academy at West Point. He is also Professor of Public International Law at the University of Reading and Professor Emeritus and Charles H. Stockton Distinguished Scholar-in-Residence at the United States Naval War College.
Major Alex Hernandez is an active-duty Army judge advocate and a military professor assigned to the Stockton Center for International Law in Newport, Rhode Island.
The views expressed are those of the authors, and do not necessarily reflect the official position of the United States Military Academy, Department of the Army, or Department of Defense.
Articles of War is a forum for professionals to share opinions and cultivate ideas. Articles of War does not screen articles to fit a particular editorial agenda, nor endorse or advocate material that is published. Authorship does not indicate affiliation with Articles of War, the Lieber Institute, or the United States Military Academy West Point.
Photo credit: Tasnim News Agency
