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The Killing of Qasem Soleimani: Assessing the Legality

Updated: Apr 16, 2020

On January 3, the U.S. military carried out an order by President Trump to kill Qassem Soleimania senior Iranian General and architect of Iran’s broader security policy and military operations in the Middle East. Soleimani was killed near Baghdad airport by a U.S. drone strike along with several other Iran-backed militia fighters and Iraqi military personnel. Notwithstanding the geopolitical significance and consequences of this attack, what are the legal grounds for the Trump administration’s course of action, and what does international law have to say?

U.S. Presidents have broad authority as Commander-in-Chief and Chief Executive to order the use of force by the U.S. military. Under Article II of the U.S. Constitution, the President has the power to order the use of military force to defend the United States and its citizens against actual or anticipated attacks without Congressional authorisation – powers which have incrementally expanded since 9/11. There is a complicated, ongoing debate concerning domestic legal and constitutional issues in the U.S. regarding presidential authority to order the strike on Soleimani. Nevertheless, given that the attack took place in the context of extraterritorial use of force, it ought to be assessed in the framework of International Law regardless of what such a debate or later investigations might find on the issue of presidential authority.

The strike against Soleimani brings to the fore many different aspects of International Law. The first and most important distinction to be made is between jus ad bellum and jus in bello. In short, the former contains the rules on when a state has a right to use armed force while the latter includes rules on how a state is to conduct itself once hostilities have started. These rules of conduct include, among other things, the Geneva Conventions’ rules on standards for humane treatment in armed conflict. Importantly, these rules are applicable regardless of whether hostilities started in accordance with the rules on jus ad bellum or not. There are differing opinions on whether the Geneva Conventions apply to the strike against Soleimani, but this article will not discuss the issues of jus in bello further nor will we consider aspects related to International Human Rights Law (IHRL). Instead, we will focus on the rules of inter-state use of armed force – jus ad bellum.

Use of Force and Involved Parties

Article 2(4) of the UN Charter forbids the use of armed force. That said, armed force may be used if the UN Security Council has authorised it under a mechanism described in Article 39 ff. The use of armed force is also permitted if the state, on which territory an armed attack is being carried out, has given valid consent to such actions. For example, when major powers assist struggling governments to address, among other things, terrorism. Moreover, according to Article 51 of the UN Charter, the use of armed force is allowed in self-defence, but preventive strikes are forbidden unless there is clear evidence that the threat is imminent. Retaliatory strikes for past events are, however, always forbidden.

The Soleimani Strike in Relation to Iraq

The use of force against Iraq entails the use of force within its territory and against its nationals. There has been no claim that the U.S. was acting in self-defence vis-à-vis Iraq so we can safely disregard this remote possibility. Neither has there been any claim that the U.S. received consent from Iraq to carry out the attack. Opinions differ on whether non-consensual attacks can be justified according to International Law. One such justification rests on the assumption that the state in question is incapable or unwilling to deal with an imminent threat. For example, when a state is colluding with another state or entity that poses an imminent threat – in this case, to U.S. forces or interests. In its letter to the UN Security Council, the U.S. made no mention of the violation of Iraqi sovereignty even though it has the burden of proof that the conditions justifying a strike were present in the Soleimani case. Regardless of which theory on armed force being used in a third country you subscribe to; it seems unlikely the U.S. can justify the strike on Iraqi territory.

The Soleimani Strike in Relation to Iran

Regarding Iran, the U.S. has in its letter to the UN Security Council claimed to have acted in self-defence. The schoolbook example of self-defence is when a state is subject to ongoing attack from another state. It is generally claimed that a right to self-defence also exists towards imminent threats (picture, if you will, an invading fleet approaching a state’s territorial waters). The U.S. has listed several events that led to the strike on Soleimani in their letter to the UN Security Council. But, according to most commentators, these do not alone, or in conjunction, constitute an ongoing attack. It is, therefore, not entirely clear whether the U.S. government claims that there was an ongoing attack or that there was a present threat which was “instant, overwhelming and leaving no choice of means, no moment of deliberation”– a core tenet of international jurisprudence regarding “imminence” as per the “Caroline Test”.

The “Caroline Test” applies in cases where a defensive action was taken before an armed attack occurred. If the attack was indeed “imminent” as claimed by the U.S., then it stands to the fact that the strike could pass the Caroline Test because it was an act of anticipatory self-defence.

The burden of proof that an imminent threat existed thus lies, in this case, with the U.S. government. For many different reasons, it seems unlikely that they will be able to successfully present such proof. One reason for this is that Soleimani was active on a strategic rather than operational level. His death would, “probably” or “reasonably”, not have stopped any planned attacks but instead seems to have served the purpose of demonstrating to the Iranian leadership that the Trump administration is not hesitant to take lethal action if its perceived interests in the region are threatened. New evidence that Trump authorised Soleimani’s killing 7 months ago, reinforces this argument.

The letter to the UN Security Council also speaks about deterring future Iranian attacks and reducing Iranian capabilities. Even though other statements by the Trump administration have referred to “imminent” threats, these have not been backed up by material evidence and have not been included in the formal letter to the UN Security Council. This should probably be interpreted as at least an indication that the strike against Soleimani was not connected to any imminent threats. Furthermore, the U.S. must also prove that the use of armed force was necessary, that is, the best and only alternative, and that such military force was proportionate to the extent necessary. Some may feel the rules on the use of armed force are too restrictive, especially when discussing its own country’s right to self-defence. Leading scholars and experts are, however, in relative agreement that this is the correct interpretation of the jus ad bellum.

Iran’s Response to the Strike

In situations of confrontation between states, it is not uncommon that the rules of International Law are ignored or deliberately overlooked. The purpose of the UN Charter and International Law is, in these situations, to deescalate the tensions and avoid circumstances of tit-for-tat reprisals between parties to a conflict. Even though a state has been subject to an armed attack, it is not entitled to take whichever countermeasures it wants. It is, therefore, plausible that Iran’s strikes against military bases in Iraq are also in violation of jus ad bellum. Particularly problematic in this regard is the fact that the Iranian attacks (once again) took place on Iraqi territory.

Peaceful Resolution of Disputes

Part of the role of the UN Security Council is to handle a crisis such as the Soleimani incident. It is a welcome development that it has been formally brought to its attention so that talks on deescalating the situation can begin instead of further unilateral action. Furthermore, the parties to the conflict can attempt to bring a case before the International Court of Justice of the UN in order to receive a verdict on the legality of the actions taken. Reports have indicated that Iran will seek such action. A problem with rulings from the ICJ (and international law in general) is that even though the verdicts are binding, means of enforcement are often limited – especially when it involves a permanent member of the UN Security Council such as the U.S.

The Soleimani case represents, in so many ways, an era of “new behaviours” in international affairs. Nevertheless, the international law community should remain steadfast in applying the norms and criteria of the UN Charter and Customary International Law. It is, after all, not International Law that is in crisis. Politics or “politicking” seems to be the primary culprit because it increasingly seeks to sidestep the norms of international jurisprudence.


Wayne Stephen Coetzee is a senior lecturer in political science and assistant coordinator of the International Programme for Politics and Economics at University West, Sweden. His research focuses on the political economy of arms trade, foreign policy analysis, and Nordic development studies.

David Jersenius is a lecturer in law and a member of the advisory board for the faculty of Economics and IT at University West, Sweden. His research and teaching interests include international business law, international law, environmental law, and tort law.


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