Of Proxies, Self-Defence and Reprisals

[Ayesha Malik is Deputy Director at the Research Society of International Law where she leads the Conflict Law Centre. She is also Adjunct Faculty at the Lahore University of Management Sciences where she teaches international criminal law to undergraduate students.]

On April 1, Israel attacked Iran’s consulate in Damascus killing Iranian generals and military officers. Nearly two weeks later, Iran responded by firing over 300 missiles at Israel, most of which were intercepted. On April 19, Israel retaliated against Iran with a missile strike which may have damaged an air base. The question of whether Israel had the right to attack and whether Iran had a right to self-defence is complicated, in large part due to the various tests for attribution at play. This article explains how these tests can be applied to Iran, its proxies, and Israel. 

Israel vs Iran (ignoring Hezbollah and Hamas)

The Attack of April 1

A state has the right to self-defence against an armed attack (Article 51, UN Charter) provided its response is necessary and proportionate (Nicaragua, para.194). As embassies (and arguably, by extension, consulates) abroad are considered emanations of the state, Israel’s attack on Iran’s consulate in Syria is an armed attack against Iran to which Iran has the right to self-defence. The US has long held that attacks on diplomatic and consular missions can justify action in self-defence (including those against US embassies in Nairobi and Dar-es-Salam in 1998).

Here, UN experts agreed that Iran has a right to respond, but argued it would be unnecessary as “self-defence is only lawful where it is necessary to stop a continuing armed attack”. Similarly, Eliav Lieblich stated that given Iran responded two weeks after the attack, and its leaders framed it as an act of punishment or retaliation, this makes it a “prohibited forcible reprisal rather than a defensive action.”

This argument merits further analysis.

Self-Defence or Reprisal?

It is accepted that self-defence must be defensive and cannot be only retaliatory or punitive (ILC Articles Commentary to Art.49, para (1); Schmitt; Wood page 352). The line between lawful self-defence and unlawful reprisal occurs along a sort of defensive-to-offensive conveyor belt, wherein defensive force is lawful, whereas that taken to punish or deter the state from attacking again is an offensive reprisal (see Bowett and Schmitt). This is not at issue when an armed attack is continuing or ongoing, as in an invasion or occupation, but once over, some argue, there is no right to self-defence unless another armed attack is imminent. 

Kretzmer calls this the ‘halting and repelling’ approach, under which a state may only use force when the armed attack is occurring and ongoing. Under the ‘trigger theory’, a state cannot use force until an armed attack occurs but once it has, it can defend itself against that attack as well as future threats posed by the aggressor, whether imminent or not. This force can deter the aggressor from repeating its attack or destroy its military potential to mount another attack in the near future. 

The ‘halting and repelling’ argument was ironically one Iran itself adopted in Oil Platforms (Iran’s reply, 7.13(5)) when it said “once an attack is over…there is no need to repel it, and any counter-force no longer constitutes self-defence. Instead it is an unlawful armed reprisal or a punitive action.”

The United States disagreed (Counter-Memorial and Counter-Claim, 4.27), stating “self-defence is not limited to repelling an ongoing attack while it is in progress. A State can also use force in self-defence to remove continuing threats to its future security.” It further argued that Iran’s view would mean America’s right to self-defence after 9/11 “ended once the hijacked aircraft had struck their targets” (para.28.14).   

Kretzmer argues the “halting and repelling” school is removed from reality, stacking the deck highly in favour of the aggressor state, which only needs to worry about halting and repelling the attack, and no more. Even proponents, like Corten (p.486), contend that a state can respond to a completed attack, as to argue otherwise “would be a plainly absurd and unreasonable interpretation” of the objective of self-defence.

The ‘trigger theory’ seems to be supported by state practice, especially the US response to 9/11. The US noted its invasion of Afghanistan was responding to these attacks but was also “designed to prevent and deter further attacks”. This intervention, Green notes, was generally viewed as lawful self-defence by states and scholars alike. 

Under this argument, a victim state can respond to an armed attack (after it has happened) with force, even if that force’s dominant aim is punitive and to deter further attacks (section 3A). This echoes Iran’s political rhetoric following the attack, when Iranian leader Khamenei said Israel “must be punished and it shall be”. However, Iran’s letter to the Security Council also cited “further military provocations by the Israeli regime”. 

The difficulty is determining whether future attacks are really imminent and if this broadens the right to self-defence in more unsettled terms. Green argues the test for imminence may be more loosely interpreted when a state has already suffered an armed attack, though it must still be more than a vague future threat. Whereas Schmitt maintains that the same test for imminence will apply but, given the state has been attacked already, it is easier to conclude it will be attacked again. Iran could argue future attacks were imminent, particularly since a UN Assistant Secretary General informed the Security Council on April 2 that Israeli officials “have suggested that more will occur in the future.” 

A time delay (around two weeks in Iran’s case) was also argued to be indicative of a desire to punish rather than defend with the Caroline incident cited in support, wherein the need for self-defence must be “instant, overwhelming, and leaving no choice of means, and no moment for deliberation”. Brownlie argues this incident, as well as other customary international law before the 1920s, has no bearing on Article 51. Therefore, a more relaxed approach to a time delay can be taken contrary to that required by Caroline. This is also supported by state practice as a month lapsed between 9/11 and the US’ response. 

Therefore, the aim to deter future attacks can be a component of the justification for self-defence, and not simply halting and repelling a continuing armed attack. 

Hamas or Hezbollah Were ‘s=Sent by’ Iran

Israel has arguably suffered armed attacks (grave uses of force beyond mere frontier incidents (Nicaragua, para.194) by both Hamas and Hezbollah. As the threshold is quite low, both October 7, 2023 by Hamas and hostilities along the Israel-Lebanon border by Hezbollah may well qualify. While the accumulation of events doctrine is controversial, as there have been over 4,400 violent incidents involving Israel and Hezbollah which have caused casualties, it is likely that at least some of these rose to the threshold of an armed attack. 

Israel could claim it has been in an armed conflict with Iran through its proxies Hezbollah and Hamas at least since October 7, 2023. Israel would have the right to use force against Iran in self-defence only if Iran had ‘sent’ Hezbollah or Hamas to attack Israel or had ‘substantial involvement therein’. This test, laid down in Article 3(g) of the Definition of Aggression, was followed by the ICJ (Nicaragua, para.195) in determining the attribution of an armed attack by a non-state actor to a state to justify self-defence against that ‘sending’ state. The ICJ clarified that ‘sending’ or ‘substantial involvement’ in an armed group does not include mere funding, arming, or giving military logistical support (para.195). 

The extent to which Iran’s support for Hamas goes beyond these forms of support is unclear. Despite some early reports to the contrary, Iran apparently did not know about Hamas’ plan to attack and was not involved in planning, resourcing or approving it. It is unlikely Hamas was sent by Iran or that Iran had substantial involvement in the attack. Iran is arguably not substantially involved in Hamas even outside this attack [more on this below], so Israel would not have the right to self-defence against Iran for October 7. 

Iran arguably exercises greater control over Hezbollah, providing most of its training, weapons, and funding and sharing goals, strategies and materials. Reports indicate that “there have been a number of occasions throughout the group’s history where Tehran either directly influenced its decisions or blatantly gave it specific orders”. While Iran may have had ‘substantial involvement’ in Hezbollah, earlier evaluations (from 2007) have not determined this rose to the level of aggression. 

The UN experts’ statement also acknowledges that “Israel does not appear to have been exercising self-defence on 1 April because it presented no evidence that Iran was directly committing an “armed attack” on Israel or sending non-state armed groups to attack it”. Therefore, while this may be a credible argument, it is not one Israel has made. 

Iran has Overall Control over Hezbollah or Hamas

Assuming Hamas is in a non-international armed conflict (NIAC) with Israel alongside a pre-existing occupation, Iran’s ‘overall control’ over Hamas may render this an international armed conflict (IAC). Similarly, assuming Israel is in a NIAC with Hezbollah, Iran’s overall control over the group may also make this conflict international. 

Applying the Tadić ‘overall control’ test (para.137), if Iran had overall control over Hezbollah or Hamas (since at least October 7, 2023), then the April 1 attack would be occurring within a pre-existing IAC prompting application of the laws of war and not the law on the use of force. The ICTY held (Tadić, para.131) that overall control goes beyond “equipping and financing the group”, and includes “coordinating or helping in the general planning of its military activity.”

As Iran may not have known about Hamas’ October 7 attack, that undermines this argument somewhat. Moreover, reports indicate Iran has a weaker grasp on Hamas than commonly thought given they are the only non-Shia group in its trifecta of proxies, and relations between them ruptured after Iran’s continued support for Syria’s Assad which Hamas disagreed with (Frankel, p.59, also generally Baconi). Some recent reports indicate Iran does not direct or control Hamas’ actions despite retaining some influence over the group (in its ability to halt strikes), and Hamas does not coordinate its plans with Iran.

Iran may not have ‘overall control’ over Hamas but it may over Hezbollah. While Hezbollah is gaining autonomy and outgrowing its dependence on Iran, it still has greater input on Hezbollah’s strategy and a shared ideological belief in the wilayat-e-faqih (rule by an Islamic jurist). While there are varying opinions on the extent of this input (some contradictory), Khamenei reportedly arbiters the decisions of Hezbollah’s leaders and Hezbollah became involved in the Syrian civil war in 2011 at Iran’s request (something Hamas notably refused to do) fighting under Iranian commanders. Also, Iranian generals provided strategic advice to Hezbollah in the Israel-Lebanon 2006 war, though apparently, even Israeli military officers did not believe Hezbollah was acting on the instructions of Iran even then. 

If Iran’s overall control over Hezbollah could be established, Israel would have the right to attack military targets in Iran. While Iranian combatants and Hezbollah members were at the consulate in Damascus, there was no armed conflict between Israel and Syria or attribution between these groups and Syria allowing for the use of force against Syrian territory. 

Conclusion

Derek Bowett, writing about the difference between self-defence and reprisals, quoted the Soviet representative to the Security Council in 1964 as saying: “The difference between the right of self-defense and the right of retaliation is quite obvious to any first year student at any law school”. Unfortunately, as this article demonstrates, this obvious difference is not so obvious. The war between Iran and Israel is further complicated by proxies and conflicting accounts of Iran’s level of control over and involvement in them, which this article has attempted to shed some light on.