General Qasem Soleimani, the Commander of Iran’s Quds Force was killed on 3rd January 2020 near Baghdad airport by a US drone strike.

In the wake of the killing which has escalated tensions in the ever-volatile Middle East, one of the predominant questions has been on the legality or otherwise of the US strike. As a justification of the strikes, Trump’s Secretary of State, Mike Pompeo and other senior officials of the Trump administration have maintained that shortly before his killing, General Soleimani was planning multiple attacks on US military bases and diplomats in the Middle East. They also argue that the planned attacks on US interests were imminent and the killing was to disrupt the planned attacks and to deter future attacks. Trump also stated that the attack was not to start a war with Iran but to avoid a war.

The argument advanced by the US is that of self-defence which is a legitimate use of force in international law. While the US is yet to make the evidence of the imminence of the planned attacks public, the imminent attacks argument is advanced to confer legality on the killing. Assuming there was an imminent threat of attack on US interests as claimed by Trump and senior administration officials, the question is whether the imminence of the planned attacks confers on the US a right of preemptive self-defence which renders the killing legal under international. This article seeks to answer this question through an analysis of the current normative order on use of force and the doctrine of self defence under international law.

Self-defence Under Customary International Law

Rules of customary international law comprise the practice of states which have been accepted by the states as imposing an obligation. Customary international is a product of state practice and opinio juris sive necessitatis.

The right of self-defence is a natural right inherent both in states and individuals. The right is recognized under customary international law and available to states in the event of armed attack. The scope and limits of the right were enunciated by the US Secretary of State, Daniel Webster in the Caroline Case. In the Caroline Case, the Caroline, a ship owned by US nationals which was allegedly used in delivering supplies to Canadian rebels who were waging an anti-British insurrection was attacked by British Forces in 1837 while the ship was moored on US territory at night. In the attack, the British killed and injured US nationals who were on board the ship, set the ship on fire and sent the ship over the Niagara Falls. The British claimed their action was in self-defence. This argument was however rejected by the US and in a letter by Daniel Webster to Lord Ashburton, a Special British Representative in the US, he argued that the British failed to show the necessity for self-defence which was “… instant, overwhelming, leaving no choice of means and no moment for deliberation”. He further argued that the British also failed to show that the attack was proportional to the threats it responded to.

The two criteria which emerged from this diplomatic exchange for a justifiable exercise of the right of self defence, including preemptive self-defence are necessity and proportionality.[1] Therefore a State seeking to justify the use of force in self-defence under customary international law must ensure that the use of force meets these criteria.

Customary international law equally recognized the right of preemptive self-defence[2] and allows States to deploy force in response to an imminent attack. However, with the formation of the United Nations (UN) and adoption of the Charter of the United Nations (the Charter), a new international legal regime emerged which provides a treaty framework for use of force by States.

Use of Force and Self-Defence Under the UN Charter

Following the victory of the Allied Forces in the Second World War, fifty-one (51) countries founded the UN to craft a new world order founded on international peace and cooperation. The founding members of the UN, determined “to save succeeding generations from the scourge of war, which twice in our lifetime has brought untold sorrow to mankind”,[3] adopted the Charter of the UN in 1945. One of the cardinal purposes of the UN is “to maintain international peace and security, and to that end: to take effective collective measures for the prevention and removal of threats to the peace, and for the suppression of acts of aggression or other breaches of the peace, and to bring about by peaceful means, and in conformity with the principles of justice and international law, adjustment or settlement of international disputes or situations which might lead to a breach of the peace.”[4]

In pursuance of the purposes of the UN, the Charter prohibits unilateral use of force by states in their international relations. Article 2(4) of the Charter provides that:

“All Members shall refrain in their international relations from the threat or use of force against the territorial integrity or political independence of any state, or in any other manner inconsistent with the Purposes of the United Nations.”

Under the present Charter regime, the right to use force for the maintenance of international peace and security is conferred exclusively on the Security Council of the UN.[5] However, notwithstanding the prohibition of unilateral use of force by States, Article 51 of the Charter guarantees the right of individual or collective self-defence in the event of an armed attack. The Article provides that:

“Nothing in the present Charter shall impair the inherent right of individual or collective self-defence if an armed attack occurs against a Member of the United Nations, until the Security Council has taken measures necessary to maintain international peace and security.”

Article 51 offers the only legal basis under the Charter for unilateral use of force which is not sanctioned by the Security Council. However, scholars are divided on the precise import of article 51. Some scholars and commentators (restrictionists) argue that Article 51 can only be invoked in response to an actual armed attack. By this logic, “a would-be victim would have to wait until it becomes an actual victim before it can use military force in self-defence.”[6] Others (“counter-restrictionists”) are of the view that Article 51 does not restrict or abolish the customary law right of preemptive self-defence. This school of thought argues that the reference in Article 51 to an “inherent right of self-defence” implies that the Charter preserves the right of self-defence in its customary international connotation which encompasses preemptive self-defence.

In the light of these competing interpretations, there is at present a lack of consensus amongst scholars and commentators on the question of abolition or restriction of the right to preemptive self-defence under the Charter. The International Court of Justice (ICJ) has also not made an authoritative pronouncement on the question of preemptive self-defence under the Charter regime. However, the ICJ in its judgment of 27th June 1986 in Nicaragua v. United States of America[7] held that the customary international law right of self-defence survives the Charter and exists alongside Article 51. In response to the arguments of the US that the customary international law regime of use of force has been completely subsumed by the UN Charter, the ICJ stated that:

“On one essential point, this treaty itself refers to pre-existing customary international law; this reference to customary law is contained in the actual text of Article 51, which mentions “the inherent right” of individual or collective self-defence which “nothing in the present Charter shall impair” and which applies in the event of an armed attack. the Court therefore finds that Article 51 of the Charter is only meaningful on the basis that there is a “natural” or “inherent” right of self-defence, and it is hard to see how this can be other than of a customary nature, event if its present content has been confirmed and influenced by the Charter. Moreover, the Charter, having recognized the existence of this right, does not go on to regulate all aspects of its content. For example, it does not contain any specific rule whereby self-defence will warrant only measures which are proportional to the armed attack and necessary to respond to it, a rule well established in customary international law. Moreover, a definition of the “armed attack” which, if found to exist, authorizes the exercise of the “inherent right” of self-defence is not provided in the Charter and is not part of treaty law. It cannot therefore be held that Article 51 is a provision which “subsumes and supervenes” customary international law.”[8]

The ICJ however made no comment on the legality of preemptive self-defence in response to an imminent attack on the basis that “the possible lawfulness of a response to the imminent threat of an armed attack has not been raised.” “The Court has therefore to determine first whether such attack has occurred, and if so, the measures allegedly taken in self-defence were a legally appropriate reaction a matter of collective self-defence.”[9]

While the question on the legality of preemptive self-defence remains unanswered, the above reasoning of the I.C.J. gives credence to the argument that the customary international law right of self-defence was merely recognized by Article 51 and not abolished. This supports a plausible conclusion that the right of preemptive self-defence survives Article 51 and can be exercised where there is an imminent threat of armed attack.

There is also no evidence to the effect that post the recognition of the inherent right of self-defence under Article 51 of the Charter, preemptive right of self-defence has been abolished by subsequent customary international law. State practice since the adoption of the Charter has been inconsistent. The response of states to claims of preemptive self-defence post Charter has vacillated between outright rejection, tolerance and acceptance. The Security Council deliberations on the Cuban Missile Crisis of 1962, the Six-Day War of 1967 and the Attack on the Osirak Reactor all bear testimony to the lack of consensus on the lawfulness or prohibition of preemptive self-defence. In the absence of such consensus, any post-Charter customary law prohibition of preemptive self-defence, the right inures to states and can be justified where the criteria of necessity and proportionality are satisfied.

In the light of the foregoing analysis, the legality or otherwise of the killing of General Soleimani depends on whether there was imminent attack on the US by Soleimani as claimed by the US. If the planned attack met the threshold of imminence, it is the view of this author that the killing was a justifiable exercise of the inherent right of self-defence. According to Pufendorf:

“… when a man, contrary to the laws of peace, undertakes against me such things as tends to my destruction, it will be a most impudent thing to demand of me that I should his person inviolate, that is, that I should sacrifice my safety so that his villainy may have free play … It is reasonable for a man who is about to suffer some dread event to defend himself rather than to accept it. Otherwise, the victim of misfortune is accused of cowardice.”[10]

It is impractical to expect states to stand by without taking preemptive action in response to imminent threats of armed attack. Therefore, provided that there was an imminent attack from Soleimani, his preemptive killing is lawful and justified. But if no such imminent threat existed at the time of the killing, the killing constitutes an unlawful use force by the US.

Agbada S. Agbada is a Lagos based legal practitioner and can be reached on [email protected]

[1] Professor Anthony Clark Arend, International Law and the Preemptive Use of Military Force (2003) The Washington Quarterly, 26:2, pp. 89-103.

[2] See Sean D. Murphy, The Doctrine of Preemptive Self-Defence, 50 Vill. L. Rev. 699 (2005). Available at https://digitalcommons.law.villanova.edu/cgi/viewcontent.cgi?article=1215&context=vlr (last accessed on 5th January 2020)

[3] Preamble to the UN Charter

[4] Article 1 of the UN Charter.

[5] See article 41 of the Charter.

[6] Professor Anthony Clark Arend, International Law and the Preemptive Use of Military Force (2003) The Washington Quarterly, 26:2, pp. 89-103.

[7] Military and Paramilitary Activities in and Against Nicaragua (Nicaragua v. United States of America) Merits, Judgment, I.C.J. Reports 1986, p. 14.

[8] Ibid. at p. 94.

[9] Ibid. at pp. 27-28.

[10] Samuel Pufendorf, “De Jure Naturae Et Gentium Libri Oct,” Vol. Two, in the Classics of International Law, New York, Oceana Publishing Inc (1964) p. 265. Cited by Fred Aja Agwu, United Nations System, State practice and the jurisprudence of the use of force, Malthouse Press Limited (2005), p. 48.