The Houthi Attacks Against the UAE: Rules of Conflict and International Law of State Responsibility

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The conflict in Yemen has spread beyond the confines of Yemen, with the Houthis mounting attacks against critical infrastructure in Saudi Arabia and the United Arab Emirates (UAE) using drones and missiles. This article explores the recent strikes against Abu Dhabi under international humanitarian law, and explores the possibility of attribution under international law of state responsibility to Iran, a primary funder and supporter of the Houthis.


The UAE has been involved in Yemen since joining the Saudi-led Coalition in 2015. Despite being heavily involved in the conflict, the UAE has been phasing out its withdrawal since 2019, while maintaining its support of the Giants Brigades in Yemen. The Houthis’ response against the UAE, up until recently, has been indirect.

On the 17th of January this year, the Houthis launched a successful drone and missile attack against Abu Dhabi International Airport and oil infrastructure, injuring six and killing three individuals. The attacks were condemned by its allies (here, here, and here) and the UN Secretary General. A week later, two ballistic missiles were fired against the UAE but were intercepted before landing.

This wouldn’t be the first time the Houthis have targeted critical civilian infrastructure. In 2019, Saudi Aramco, the state-owned petroleum and natural gas company, the third largest company in the world, was targeted by the Houthis using uninhabited armed vehicles (UAV) and cruise missiles, causing a disruption to crude oil supplies. Likewise, in 2021, the Houthis targeted Abha International Airport using the Qasef-2K drone and Quds-1 missile.

The politics of air strikes

The Houthis’ ability to compromise global oil-market security and penetrate some of the world’s top buyers of fighter jets using missile technologies and know-how completely undermines the war effort carried out by the Coalition. It is important to mention here that the war has primarily been fought inside of Yemen, legitimized by the consent of President Hadi back in 2015, and so the extension of this war beyond the confines of Yemen presents a new level of threat to the Emiratis. The attacks not only undermine the UAE’s defence capabilities as one of the Gulf countries’ most advanced military powers, but they also undermine any chances for the talks between Iran, Saudi Arabia, and the UAE to have meaningful outcomes as the Houthis, primarily armed by Iran, show no interest in a ceasefire. Equally important, these attacks reveal that the UAE cannot really withdraw from the conflict just because it says it is.

International Humanitarian Law

The Houthis are a non-state armed group under which Additional Protocol II of the Geneva Conventions applies to their conduct. Their ability to exercise territorial control over large swathes of Yemen, their organizational structure, responsible command, and ability to ‘impose discipline’ qualifies them to carry out ‘sustained and concerted military operations’, satisfying the definitional aspect under AP II. Therefore, they are bound by the rules of war, as are the state actors participating in the conflict.

Distinction and Proportionality

The principles of international humanitarian law unequivocally prohibit the use of force against civilian objects. This cardinal rule is derived from the customary principle of distinction which provides that parties to the conflict must at all times distinguish between civilian objects and military objectives and must only direct attacks against military objectives. This is further legitimized by Article 13 of Additional Protocol II of the Geneva Conventions, applying to non-international armed conflicts, which provides a broad general protection over the civilian population, stipulating that civilians ‘shall not be the object of attack’.

According to some state practice, airports may be considered legitimate military objectives. However, this is caveated by the fact that they must carry some military weight to qualify as legitimate. The same applies to the targeted oil sites. According to the Commission of Jurists which met at the Hague in 1922 and drafted an interpretation of military objectives, air bombardments are only legitimate if they also qualify as military objectives. In this interpretation, a non-exhaustive list of objectives were cited including ‘military forces, military works, military establishments or depots, ammunition or characterized military supplies, lines of communication or transport which are used for military purposes’. While not codified, this nevertheless helps define the parameters of what is considered a legitimate military aim.

Since the object of attack, the Abu Dhabi International airport, presents no military objective and is a critical civilian infrastructure, the attacks by the Houthis are, at face value, entirely unlawful and serve no military purpose beyond the unlawful intimidation of the civilian population. Likewise, the strikes against the oil facility located in Musaffah strikes at the heart of the UAE’s economy but ultimately serves no military objective.

Moreover, the attacks are indiscriminate under IHL. The International Court of Justice (ICJ) in its Advisory Opinion on the Legality of Nuclear Weapons made it clear that the prohibition of indiscriminate weapons is a cardinal rule of IHL (§78). According to an IISS assessment, the ballistic missile used against the airport was the Zulfiqar missile, an Iranian derivative of the Scud-B missile. Scud missiles and by extension, their derivatives may qualify as indiscriminate weapons given their wide circular error probable (Zulfiqar has a circular error probable of 1000 meters) and inability to distinguish between specific military objectives, thereby causing excessive collateral damage. The Quds-2 cruise missile that targeted the oil facilities, on the other hand, is a precision strike weapon and would therefore not generally qualify as indiscriminate.

This brings us to the principle of proportionality, which makes no legal sense here since the principle applies to military objectives, and not civilian objects. The principle of proportionality prohibits attacks against military objectives which are ‘expected to cause incidental loss of civilian life, injury to civilians, damage to civilian objects, or a combination thereof’ and would be excessive when weighed against the concrete and direct military advantage.

‘Military objectives’, not merely a term of art but a term bearing legal weight, are defined under customary international law as ‘objects which by their nature, location, purpose or use make an effective contribution to military action and whose partial or total destruction, capture or neutralization, in the circumstances ruling at the time, offers a definite military advantage.’ The spaces targeted are not objects by nature, location, purpose, or use advance the military aims of the Houthis since there is no military link to the targets. Since the airport and oil facilities do not constitute military objectives to begin with, an analysis of proportionality is futile. Therefore, it does not matter whether the collateral damage was excessive since the target is unlawful to begin with.

International Law of State Responsibility and Attribution

Since 2011, Iran has supported the Houthis with arms, financing, training, and has significantly expanded its support after 2015. According to the UN Panel of Experts on Yemen report in 2016, Iranian-grade ballistic missile remnants had been transferred into Yemen and ‘re-assembled before being launched at Saudi Arabia’ (IISS Strategic Dossier, § 163-164). Iran has transferred missile and UAV systems, small arms, rocket-propelled grenades and other arms to the Houthis since then.

It is therefore worth assessing Iran’s role under International law of state responsibility for the Houthis and whether the Houthis can be equated as an ‘agent’ of the Iranian Government acting on its behalf (ICJ Nicaragua §62, 109, Genocide §391) under Article 4 of State Responsibility. The ICJ in Nicaragua devised a test of ‘complete dependence’ which requires the State to exercise a high degree of overall control over armed groups across all of their activities, insomuch as the group is completely dependent on the State. What matters is the ‘reality of the relationship’ between the Houthis and Iran in questioning whether they have any ‘real autonomy’ to negate complete dependence (Genocide § 392-394).

According to this test, Iran and the Houthis do not share a relationship of complete dependence. This is true since the Houthis exercise a significant degree of autonomy; they are an autonomous tribal group established in the 1960’s, they have their own objectives and do not answer to Iran directly. For example, in 2014, Iran warned the Houthis against overtaking Sana’a, and were completely ignored, indicating no real link between command. Likewise, complete dependence requires more than the provision of advisers, Iran would have to wholly devise strategies and tactics for the Houthis. (Talmon §500-501, Nicaragua §104, 106). The Houthis are a highly structured, top-down organization, which recruits largely from local tribes and defects of Yemen’s armed forces (§164) and the Houthis’ military doctrine does not hinge on Iran’s military doctrine, but rather derives from the Yemeni armed forces’ doctrine and years of tribal fighting (§164). Likewise, the Houthis exercise a degree of financial autonomy where they receive funding mainly from within the telecommunications sector in Saana (§ 128) and from black market fuel at the Red Sea Ports (§ 128), meaning without Iran they would still be able to continue their activities (Nicaragua §109-111). Therefore, despite clear ties with Iran in terms of training, arms, and funding, they do not share a relationship of complete dependence for the purposes of the strict control test.

Nor is the Houthis’ conduct sufficient to establish attribution under the less stringent ‘effective control’ test adopted in Nicaragua. The rules of attribution under Article 8 of State Responsibility suggest that conduct will be considered ‘an act of a State if the person or group acts on the instructions of, or under the direction or control of that State.’ The elements for attribution demand Iran’s direction or control to be an integral part of the specific conduct (Genocide § 400), rather than an overall control over the Houthis. In other words, these cumulative elements require the Houthis to be under the direction or control of Iran for this specific use of force.

According to the ICJ in Nicaragua, the organization, training, equipping, and operational support provided by the US to the contras only satisfied the partial dependence for state responsibility purposes (§112). Likewise, while Iran has provided significant support and know-how to the Houthis, this is not enough to trigger the law on state responsibility insofar as there is no established chain of command (§159-160) between the Houthis and Iran and therefore does not ‘control’ nor ‘direct’ the Houthis. Indeed, key decisions are carried under the instructions of Abdul Malik al Houthi. While the missiles used by the Houthis were likely transferred by Iran unlawfully, they were likely assembled by the Houthis themselves, further distancing from the high threshold of control required by the effective control test.

While training, arming, and financing non-state actors in Yemen may constitute an interference into the affairs of another country (Nicaragua §242), under international legal standards of responsibility, this would not qualify as having ‘directed or enforced the perpetration of the acts contrary to human rights or humanitarian law’ (Nicaragua §115).

Duty to Respect IHL

Common Article 1 of the Geneva Conventions (CA1) requires High Contracting Parties “to respect and to ensure respect for the present Convention in all circumstances”. According to the ICRC, this obligation requires States to ensure respect of IHL to both States and armed groups (§120). This imposes a negative duty on Iran not to encourage, air or assist (§154) the Houthis in their violations of IHL, if the assistance provided causally contributed to the likely or foreseeable violation of IHL (Nicaragua §256, Milanovic §1328, 1337), and such violations actually took place, which they did. According to the ICRC’s commentary on CA1, transferring weapons would violate CA1 if, based on past practice, the armed group is expected to use those weapons contrary to IHL (§162). Houthi past practice, as illustrated earlier, has targeted civilian objects contrary to IHL and are likely to continue doing for political and psychological gains. Going back to the missile components and know-how provided by Iran to the Houthis which targeted the UAE, it is likely that Iran is complicit for the acts of the Houthis in this specific instance under CA1.


The Houthis’ strategy behind the attacks against Abu Dhabi bear no legally justifiable military gains according to the laws of armed conflict. Despite Iran’s support in arms, training, and finance to the Houthis, these attacks fall below the threshold required to trigger international law of state responsibility, both under the strict control and effective control tests. Instead, the less demanding standard under CA1 may be used to invoke complicity of States assisting and encouraging others to commit violations of IHL, provided the assistance casually contributed to the foreseeable violation that took place.

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Shahd Hammouri says

March 13, 2022

There are contextual information that are distinctly left out of the scope of the article. Firstly, the classification of an airport as purely civilian is hasty. Secondly, IHL must be studied in context. The UAE is a proxy actor that is accused on a wide range of violations. Not mentioning the direct annexation of Yemeni territory. Not mentioning the severe retaliation for the attacks this article is discussing.