But these denials ring hollow. The open source evidence availableincontrovertibly shows that Iranian Shahed-136 drones have been used in Ukraine. And despite official denials, social media outlets affiliated with the Iranian State have openly boasted about the use of Iranian drones in Ukraine. It also seems incontrovertible that Iran has sold or bartered these Shahed-136 drones to Russia many months into Russia’s invasion of Ukraine, i.e. these were not weapons that Russia had purchased before the war had started, when Iran could not know how they would be used. If such was the case, Iranian officials who authorized the arms transfer must have been aware that Russia intended to use the drones in its war of aggression against Ukraine. Similarly, and on the basis of a documented and publicized pattern of Russia’s deliberate or indiscriminate attacks on civilians and civilian objects in Ukraine, the relevant Iranian officials must have been aware that the drones they provided would be used in violation of the rules of international humanitarian law (IHL).
I will argue in this post that by providing the weapons, which have now unlawfully been used by Russia against Ukraine, Iran incurred State responsibility for complicity in Russia’s internationally wrongful acts. That responsibility is two-fold. First, under the customary rule articulated in Article 16 of the International Law Commission’s Articles on State Responsibility (ASR), Iran has provided assistance to Russia’s continuing violation of the prohibition on the use of force in Article 2(4) of the UN Charter, which is of such gravity that it rises to the level of aggression. Iran is moreover in violation of Article 41 ASR, which requires States to refrain from providing assistance to violations of peremptory norms of international law, such as the prohibition of aggression. Second, Iran has violated both Article 16 ASR and Common Article 1 of the Geneva Conventions by providing weapons that Russia has used contrary to the targeting rules of IHL, specifically the principles of distinction, proportionality, and precaution.
Aggression and the ILC Articles on State Responsibility
A number of different rules of international law prohibit certain types of State complicity in the acts of other States. First, Article 16 ASR (regarded by the ICJ as reflecting customary law) provides that:
A State which aids or assists another State in the commission of an internationally wrongful act by the latter is internationally responsible for doing so if:
(a) that State does so with knowledge of the circumstances of the internationally wrongful act; and
(b) the act would be internationally wrongful if committed by that State.
Article 41 ASR complements this provision and categorically prohibits State aid and assistance to maintaining situations created by a serious breach of a peremptory norm of international law, like the prohibition on waging a war of aggression.
The constituent elements of these complicity rules have been extensively discussed in the literature (see, e.g. Aust; Jackson; Lanovoy; Moynihan). Two such elements are relevant here. First, the assistance provided by the assisting State to the assisted State must causally contribute to the latter’s wrongful act, i.e. must facilitate it. That causal nexus must be neither too high nor too low; the most common formulations used in that regard are that the assistance significantly, substantially, or materially contributed to the commission of the wrongful act. Second, the assisting State must provide the assistance with the required level of culpability or fault. I have addressed this fault element at great length in my work on intelligence sharing in military operations (see here, here and here). To put a long story short, the work of the ILC (much of it internally inconsistent), State positions, and the views of scholars have vacillated between intention and knowledge as the culpability element of Article 16. On the first approach, an assisting State would only be responsible if its officials intended to facilitate the wrongful act; on the second, an assisting State would be responsible if its officials knew that the assistance would facilitate the wrongful act. The first approach is narrower than the second and would inhibit fewer State interactions.
But that apparently stark dilemma is in my view a false one. Even if intent was the proper culpability element of Article 16, that notion can in my view encompass three distinct modes of fault: purpose/direct intent; oblique/indirect intent; and wilful blindness, defined as purpose to avoid acquiring information but for which the assisting State would have acted with indirect intent (see also Moynihan). In particular, the notion of oblique intent – commonly regarded as a species of intent in many legal systems – considers that an individual is acting intentionally with regard to a consequence if he or she is practically certain that this consequence will result from his or her actions, even if the individual is indifferent to whether the consequence will occur. For example, if I put a bomb on a civilian airliner in order to kill one specific individual aboard that plane, I do so with the purpose (or direct intent) of killing that individual. But I am also obliquely or indirectly intending to blow up the plane and kill all other passengers aboard, because that is an inevitable consequence of my action, which I am practically certain will occur, and I decide to place the bomb despite that certainty.
In the case of Iran providing drones to Russia, purpose/direct intent is not the appropriate form of fault – there is no reason to believe that Iran has provided those weapons with the conscious object of assisting Russia’s aggression against Ukraine. But oblique intent (and potentially wilful blindness) is very much relevant. Iran can be said to intentionally assist Russia’s aggression even in the absence of purpose to assist the commission of the wrongful act. If Iran (i.e. officials acting on its behalf) was practically certain that Russia will commit or continue committing the acts constitutive of aggression against Ukraine, practically certain that its own action of providing the assistance would facilitate the commission of the wrongful act, and chose to provide the assistance despite this practical certainty, then the State of Iran provided the assistance with the (oblique or indirect) intent to facilitate Russia’s aggression. And as I explained above, there is no doubt that Iran acted with such practical certainty. Russia’s aggression is unfolding on our TV screens, the weapons were sold after the aggression had started, and the only reason why Russia would be getting the Iranian drones would be to use them in Ukraine, after it had depleted its own munition stocks. Even a court (let alone the courtroom of public opinion) would easily find that the factual predicate for the culpability element of complicity was met, without having to rely on any particularly exotic forms of fact-finding.
Note, in this regard, that Iran’s practical certainty regarding Russia’s commission of a wrongful act and how Russia would use the weapons provided to it has to relate solely to the underlying facts, and not to any subjective belief that Russia is acting unlawfully. That Russia considers it had the right to invade Ukraine is irrelevant, because the illegality of its conduct is a matter of objective assessment. Similarly, that Iran might not be entirely convinced that Russia acted unlawfully in invading Ukraine – Iran abstained in the vote on the first UN General Assembly resolution overwhelmingly condemning Russia’s aggression against Ukraine, and refrained from voting on the most recent one – is also irrelevant. Article 16 ASR does not require the accomplice to subjectively believe that the principal is acting unlawfully, but only to intend the facilitation of conduct that is unlawful objectively. And, as explained, the inference that Iranian officials (obliquely) intended to facilitate Russia’s use of force against Ukraine is inescapable.
It is unnecessary at this stage to examine any other issues that arise under Article 16 ASR, such as the causal contribution of the assistance provided to the facilitation of the wrongful act. There is simply no doubt whatsoever that providing weapons to an aggressor State materially facilitates the (ongoing) commission of aggression. The same applies if Iran’s responsibility was assessed from the standpoint of the duty under Article 41(2) ASR to refrain from rendering “aid or assistance in maintaining” a situation created by a serious breach of a peremptory norm of international law, i.e. the situation created by Russia’s ongoing aggression and war of territorial conquest.
Complicity in Violations of IHL
The discussion regarding Iran’s complicity under general international law in Russia’s aggression against Ukraine is applicable mutatis mutandis to Iran’s complicity in Russia’s violations of the targeting rules of IHL, viz. the principles of distinction, proportionality, and precaution. But of relevance here is also an IHL-specific complicity rule that is in some respects arguably less demanding than Article 16 ASR. Under Common Article 1 (CA 1) of the Geneva Conventions (to which Russia and Iran are parties), States “undertake to respect and to ensure respect” for the Conventions in all circumstances. Essentially the same rule binds all States under customary law – see Rules 139 and 144 of the ICRC Customary IHL Study. The so-called “external dimension” of this overarching obligation has been much debated. The positive duty of States to exercise influence on other States in order to put an end to their violations of IHL remains controversial . But CA 1 also imposes a different (and much less controversial), negative obligation on States – not to assist third parties in their violations of IHL. This obligation is categorically different from any positive duty to exercise influence because it requires nothing more than restraint on behalf of the (potentially) assisting State.
Thus, for example, in the Paramilitary Activities case, at para. 220, the International Court of Justice held that the United States was under a duty not to encourage parties to the conflict in Nicaragua to commit violations of IHL. Similarly, according to the ICRC’s 2016 Commentary on the First Geneva Convention, para. 158:
Pursuant to common Article 1, the High Contracting Parties have certain negative obligations, which means they must abstain from certain conduct. In particular, they may neither encourage, nor aid or assist in violations of the Conventions. It would be contradictory if common Article 1 obliged the High Contracting Parties to ‘respect and to ensure respect’ by their own armed forces while allowing them to contribute to violations by other Parties to a conflict.
Again, disputes regarding the demanding positive duty to exercise influence on third parties tell us nothing about the negative duty to avoid assisting violations by third parties, which only requires restraint – e.g. not selling weapons or sharing intelligence when these would facilitate violations of IHL. Accepting the existence of the negative duty does not entail acceptance of the positive one.
The culpability element of the CA 1 complicity rule can only be less demanding, and not more demanding, than that of the generally applicable complicity rule in Article 16 ASR. In particular, at least as far as complicity in serious violation of IHL is concerned, complicity under CA 1 can be based on conscious risk-taking akin to recklessness – the State providing assistance to its partner while consciously disregarding a risk that the partner would commit a serious violation of IHL would be liable for complicity if the partner does, in fact, commit such an act and the aid provided (e.g. weapons) does facilitate it. If the risk ultimately materializes – the facilitated harm occurs – the assisting State will become complicit in it.
On the facts of Iran’s provision of kamikaze drones to Russia, the factual question of whether the relevant Iranian officials were practically certain that the drones would be used by Russia to commit violations of IHL is somewhat more difficult than with regard to their use to further Russia’s aggression (which can be done even in an IHL-compliant manner). Perhaps Iran did not (obliquely) intend its weapons to facilitate Russia’s war crimes in Ukraine. But, at a minimum, Iran’s officials must have been aware of a serious risk that Russia would use the weapons in a manner contrary to IHL, e.g. to attack civilians or civilian objects deliberately or indiscriminately, because of a documented pattern of such violations by Russia prior to the arms transfer. There is, by contrast, no evidence of any attempt by Russia to acknowledge and correct any errors in its targeting process, nor of any attempt by Iran to implement mitigation measures that conceivably could have reduced the risk that the weapons provided would be used unlawfully. This again leads us to the inescapable inference that, at least prima facie, Iran provided the drones to Russia while consciously disregarding the risk that they would be used by Russia unlawfully. As Russia has now in fact used the drones in violation of IHL, i.e. the wrongful act has materialized, Iran has also become complicit in under CA 1 (and possibly also under Article 16 ASR).
Conclusion
The international legal framework governing State responsibility for complicity in the wrongful conduct of third parties is undoubtedly complex. But Iran’s provision of kamikaze drones to Russia is a relatively easy, straightforward case of complicity, especially with regard to assisting a war of aggression and territorial conquest. To be clear, Iran’s responsibility as an accomplice is derivative; it depends on Russia’s underlying (and undoubted) violations of international law, which have now fully materialized and are ongoing. Iran’s responsibility is also limited in the sense that Iran is responsible only for its own wrongful conduct of providing assistance, and not for everything that Russia is doing. But the consequences of Iran’s assistance are particularly harmful for Ukraine and its civilian population, and like any responsible State Iran now has a duty to cease any wrongful activity and provide reparation for the injury it has caused. Iran moreover has a duty not to repeat such conduct, even though it appears to be on the verge of doing so; the Washington Post is thus reporting that:
An intelligence assessment shared in recent days with Ukrainian and U.S. officials contends that Iran’s armaments industry is preparing a first shipment of Fateh-110 and Zolfaghar missiles, two well-known Iranian short-range ballistic missiles capable of striking targets at distances of 300 and 700 kilometers, respectively, two officials briefed on the matter said. If carried out, it would be the first delivery of such missiles to Russia since the start of the war.
If such an arms transfer were to proceed Iran would again become complicit in Russia’s aggression and any violations of IHL committed by these weapons, whether under Articles 16 and 41 ASR or pursuant to CA 1 of the Geneva Conventions. The unlawful attacks that Russia has conducted using Iranian-supplied drones would dispel any uncertainty (even if such uncertainty existed) that the new weapons would be used lawfully. In short, by assisting Russia Iran is not only behaving immorally or contrary to some nebulous norms of responsible State behavior. Rather, Iran is clearly acting illegally by providing such assistance, and other States should unambiguously call out that illegality.
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Marko Milanovic is Professor of Public International Law at the University of Reading School of Law. He is co-editor of EJIL: Talk!, the blog of the European Journal of International Law, as well as a member of the EJIL’s Editorial Board.
Photo credit: The Strategic Communications Directorate of the Ukrainian Armed Forces
