The targeted killing of military commander Qasem Soleimani was an event that marked the beginning of 2020-seemingly catching the attention of the entire world. Many were left questioning the events that led to such an overtly aggressive action, and even more were left doubtful of whether it was legal under international law. We must attempt to clarify the historical context that led to the targeted assassination of an Iranian military general and unpack this question of where international law stands on the use of “defensive” force. 

Before engaging in a debate that concerns itself within the confines of international law in cases of self defense, it is necessary to understand the political tensions that ultimately led to the targeted assassination of Qasem Soleimani. As we will come to see, the assassination cannot be interpreted as a singular and independent event, but rather, a product of a complex political relationship that had been intensifying for years.

Tensions between these two political powerhouses can find their origin in a widespread historical context, but for the purpose of simplifying and contextualizing these events in a convenient manner, we will begin with the US withdrawal from the Iranian nuclear deal, formally known as the Joint Comprehensive Plan Of Action (JCPOA) in May 2018. This is understood as the key event which prompted a succession of aggressive acceleration. President Trump, an outspoken critic of the deal settled during the Obama administration, asserted, “I made clear that if the deal could not be fixed, the United States would no longer be a party to the agreement…The Iran deal is defective at its core”. Following this removal, the US initiated a policy shift which set into place a series of 12 firm and vigorous demands from dropping its nuclear programme to pulling out of the Syrian war – or face severe economic sanctions.  What followed was a first round of sanctions aimed at prohibiting trade with certain business sectors such as the aviation, carpet, pistachio, and gold markets. This was followed by a second round of sanctions intended at applying pressure to oil and banking businesses.

In 2019, Trump continued in a contingent style of antipathetic foreign policy strategy, and on April 8th he declared a branch of the Iranian military as a terrorist organization. It was the first time Washington formally labelled another country’s military a ‘terrorist group’. This action was not left unnoticed by Iranian officials, as they responded by similarly declaring the US as a “state sponsor of terrorism,” and named Washington’s military body in the area “terrorist groups”. While this was not an act of overt physical aggression, this declaration was a crucial distinction as international law on the use of force aimed at combatting terrorism offers a wider range of acceptable actions than force aimed at a state. 

The elongated period of hostile action continued to unfold. In fact, we note a sort of undeniable tit for tat in US and Iranian politics aimed at each other. On may 5 2019, the US sent an aircraft carrier to the middle east, and in response, on May 8, Iran pronounced that it would “increased enriched uranium and heavy water production,” materials that would have been prohibited under the former nuclear deal.

May 27th though presented an opportunity to minify the tenseness between Washington and Tehran with Japanese Prime minister mitigating communication between the two states. This proved an unfruitful attempt though as Iran’s leader Ayotollah Ali Khamenei refused to respond or open a dialogue with Trump. 

With this effort ultimately unsuccessful,  the same pattern of events remained intact. The US expanded military capabilities in the Middle East, and Iran backfired by continuing to advance  production of materials out-banned in the nuclear deal. In other words, despite US pressures, Iran proved unwilling to cooperate with American demands. US drones were sent and shot down by Iran, with both sides offering contrasting narratives. Ultimately, despite any retaliation from the US, Iran persisted to respond firmly to any US threat against it.  In fact, Iranian foreign ministry spokesman asserted, “We will not allow any violation against Iran’s borders. Iran will firmly confront any aggression or threat by America”. 

On July 1, Iran surpassed the limit of enriched uranium, a figure confirmed by the United Nations, and in the months that followed, adopted new missile defense systems that had been barred in 2010 international sanctions. With Iranian broadening of nuclear, military, and oil capacities, further sanctions were placed by the US and a call to the UN was made for other nations to “tighten the economic noose.”  The US claimed in a UN summit-  “One of the greatest security threats facing peace-loving nations today is the repressive regime in Iran,” and that “the regime’s record of death and destruction is well known to us all. Not only is Iran the world’s number one state sponsor of terrorism, but Iran’s leaders are fuelling the tragic wars in both Syria and Yemen, and at the same time the regime is squandering the nation’s wealth and future in a fanatical quest for nuclear weapons”. It is clear here that the US was attempting to rally support against Iran on the pretense that they were endangering the well-being of the larger international community. 

With the US secretary of State Mike Pompeo alleging that Iran was preparing “a rapid nuclear breakout,” we note once more a clear case presented by the US that accuses Iran of being a threat to the wellbeing and nuclear safety of other states. The basic idea here being that the accumulation of nuclear and military warfare is an impending danger to all. Iran, on the other hand, continued to hold a position that justified their peacekeeping attempts, yet that also defended their right to attack whenever a perceived threat materialized. “We have shown restraint … we have shown patience towards the hostile moves of America, the Zionist regime [Israel] and Saudi Arabia against the Islamic Republic of Iran … but we will destroy them if they cross our red lines”. 

All of this taken into account, we begin now with the strict narrative that encompasses the most pressing events leading to Soleimani’s assassination.  On December 27 2019 a rocket attack by Iran-backed militias to a US base in Iraq killed multiple American service members. The US responded by carrying out “defensive strikes” on said militia sites in Iraq and Syria in which 25 personnel were killed and 55 wounded. Iran, angered by this attack, supported a storm of protesters who attacked the US embassy in Iraq, setting its surroundings on fire and breaking entrances. At this time, US Secretary of Defense Mark Esper said that “there were ‘some indications’ that Iran or groups it supported ‘may be planning additional attacks’ on US interests in the Middle East”. The next day, the US assassinated Soleimani, “ the head of Iran’s elite Quds Force, and Abu Mahdi al-Muhandis, the deputy commander of Iran-backed militias known as the Popular Mobilisation Forces, or PMF”.

The actions that therefore led to the targeted assassination are revealed as compound and complex. American policy aimed at Iran was seemingly fueled by the perception that nuclear development in Iran was not a responsibility that must be upheld by a deal such as the one that Obama offered, but that rather, could be sustained through economic pressures. This proved a  false prediction though as economic tightening only fueled Iranian retaliatory action against the US and increased their nuclear capacities to unsafe and precarious levels. The question naturally emerges then on whether this targeted assassination was justified under international law. In order to fully respond we must first offer a detailed account of the confines that law on the use of force admits.

We begin with an account of the limits of law on the use of force by David Kretzmer, a notable political theorist in the field of international law. He offers a comprehensive explanation of law on the use of force, and begins with the United Nations Charter as a foundational point: “Article 2(4) of the United Nations Charter, probably the most famous of Article of the Charter, states: ‘All members shall refrain in their international relations from the threat of use of force against the territorial integrity or political independence of any state, or in any other inconsistent with the Purposes of the United Nations’”.

In other words, international law aims at a world in which force is never justified as it infringes upon the sovereignty of a state. This means that fundamentally a state should never find reason to act in aggression. Still though, the Charter did acknowledge that while this is a lofty ideal,  force is still required in modern political reality in cases of self-defense. 

This standard of self defense is the only uncontested legitimate reason to use force unilaterally that survived World War II.  Strictly speaking, it is the only permissible justification of the use of force. The confines of this principle and the exact meaning of self-defense is set out in Article 51 of the charter. First, article 51 stipulated that the right to self-defense is an inherent right of states. This means that the right to self-defense existed prior to the UN Charter and that a state’s right to defend itself is not dependent on a treaty agreement between states. The recognition of self-defense as an inherent right also suggests that there exist rules governing the right to self-defense under customary international law. That is, the right of self-defense does not find its origin in any treaty, but rather in the customary practices and inherent rights of states. With the acknowledgement of this inherent principle, the UN still set out to very clearly define its limited scope: “Even though states have an inherent right to protect themselves from armed attacks, they should not wage a prolonged war under the guise of self-defense.”  That is, a difference is strictly drawn between an action of self-defense and an attempt to wage war. Where this line stands and upon which standards we can test its limit is seemingly ambiguous. 

Kretzmer and other law analysts note that this principle of self-defense brings up many questions and problems. Firstly, is the dilemma of who has the authority to decide when is the correct time to use self-defense. This is the questions of what “objective standards” exist to decide when self-defense can be used. Generally speaking, the state which has been attacked has a right to choose when to retaliate. It is also important to note how various interpretations of the clause: “if an armed attack occurs” have been proposed. A “strict interpretation” implies that states can only act in self defense once an armed attack has already occurred. Some argue that this is unrealistic though, and that the purpose of self-defense exists as a pre-emptive tool to avoid armed attacks.  A second understanding of self defense emerges in an understanding of “imminent armed attack”. This is when,  “an armed attack may not have occurred but all the evidence shows that it will occur and waiting for it to occur would be too costly”. This second reading brings up a few of the ambiguities we have mentioned beforehand. Specifically, what is considered “imminent” may be different for many individuals and state practices. The third line of interpretation then broadens this idea of preemptiveness to a point in which states are justified in using force in cases where only the  potential of a threat is present. It is important to note here that this third interpretation is in line with the American actions towards Soleimani, as they had only a strong suspicion that successive Iranian attacks were bound to take place. 

Kretzmer notes though that the issue with such a broad interpretation of self-defense is that the line between self-defense and aggression is blurred. Still, the very fact that such a flexible interpretation of what self-defense constitutes suggests that each of these interpretations may be argued and justified. The question remains though, if states truly have this freedom of wide interpretation. Kretzmer notes that the answer lies in an understanding of the actual circumstances of the attack. In other words, armed offenses must be contextualized in the historical and political frameworks in which they exist. Only then can we know how close they lie in relation to what is strictly considered aggression or self-defense. 

At this point we see how self-defense is susceptible to many interpretations. In the strictest sense, it is only allowed after armed attacks have occurred, and in the most relaxed sense, it is allowed in response to potential armed attacks. In the case of the targeted assassination of Soleimani ,we note how someone may in fact argue that as the act was done after successive Iranian attacks, it was therefore justified within the bounds of the most strict interpretation. If this is true though, can the targeted assassination be seen as an appropriate response to subsequent Iranian missile attacks? If action is  justified, how does a state know what sort of response is appropriate and which is not. 

This question requires a more in depth look at the question of proportionality in the use of force. Paul H. Robinson notes in his article on The Inherent Right to Self-Defense and Proportionality in Jus Ad Bellum that force used by a state in self defense must meet the demands of “proportionality”. This is notably another ambiguous term- just as self-defense is interpreted among various perspectives, so is proportionality.  In fact, Robinson notes two dissenting and “competing tests” of proportionality. He begins first with the idea that conjectures do exist within these two tests in that all agree that interpretations require an assessment of whether the expected collateral damage to civilians and civilian objects of an attack on a legitimate military target is excessive in relation to the concrete and direct military advantage anticipated. In other words, will the effect on innocent civilians be justified when compared to the aggressive action that spurred defense in the first place. This is a difficult question to answer as it requires the evaluation of factors that are not strictly “quantifiable”.  

Some analysts take the position that a resort to force must pass a “proportionality test”. The “tit for tat” test then, requires that force used against an aggressor must be the same as the level that the aggressor used in the first place. This is the idea we find in “an eye for an eye” ideologies, in which action is followed by subsequent similar action.  Alternate views suggest that proportionality tests must take into account the “ends” or purposes for which the defensive state wishes to use force . In other words, proportionality should therefore seemingly be based on an assessment of the force used in relation to that end. Ultimately we find though that in customary international law both interpretations of proportionality have been employed interchangeably and that flexibility within interpretative lenses suggest a flexibility in its application. 

We find then a position in international law which allows a flexible interpretation of many of the terms which bind states through the UN charter. On the one hand, self-defense can take on many forms of interpretation in which actions of force are justified if an imminent attack is present. What a state considers “imminent” is not clear cut, and so far as a state has ample justification for the mere possibility of attack, the case may be considered valid. In the case then of the targeted assassination of Soleimani, the fact that the US had evidence of prior acts of aggression, and a growing suspicion that further attacks would follow justification seems to exist within the confines. Furthermore the question of proportionality also allows for a wide capacity of perception. The killing of a general does not seemingly fall under the category of “tit for tat” proportionality, as Iranian action was not aimed towards individual leadership but rather towards military bases. As a result, we see a proportionality argument emerge that takes on the form of “means-ends.” In other words, targeted assassination was aimed at the “ends” or intention, which was to curtail any any subsequent agressive action. 

In fact, most analysts note that US actions do fall within the confines of these interpretive junctures. The argument is that the threat posed by Soleimani’s plans was “imminent” and that the US response was “defensive”. Once again,  we note that defensiveness and  imminence are prerequisites that must be proven if a state such as the US is to justify defensive action (Lister). “The test of imminence” was proven on the account that Soleimani was “actively plotting” against the US. Secretary of State, Mike Pompeo claimed that actions “would have put dozens if not hundreds of American lives at risk”. The test of defensiveness was proven on the account that Iran had shown extreme aggressiveness in the months that prequeled the killing. 

Still others do question and doubt the legality of the targeted killing. These doubts rest primarily on the basis that the killing appears to be an occurrence that was “far more retaliation for past actions than anticipatory for imminent self-defense”. Namely, the basic argument is that the long history between Iran and the US and the undeniable agressions taken by both states prove that this was a long standing and double sided war. The effort of the US then to paint the event as “self-defense” cannot be justified as it was an outward aggression based on retaliation. Many do not deny that there was a threat, yet the standard of immanence that the US argues is not easily accepted by all. Lastly, critics rest their case on the fact that Trump’s jurisdiction to kill Soleimani was not permitted under US law and that he should have notified Congress before such a drastic measure was conducted.

In the end, we find that the legality of the targeted assassination of Soleimani rests upon questions of self defense, eminence, and proportionality. What one may consider as reasonable proof for these standards is not unified and exact. Despite these analytic discrepancies, we note that American action does fall within the ambiguous confines that they permit. One who interprets self-defense in the strictest sense will therefore be doubtful of its legality, and one who interprets self-defense in its loosest form will uphold its legality. Ultimately though the fact that such vast application of reasoning exists fuels the idea that the US did not necessarily act in direct opposition with international law on the use of force. 

Works Cited

Al Jazeera. “US-Iran Tensions: Timeline of Events Leading to Soleimani Killing.” Iran News | Al 

Jazeera, Al Jazeera, 8 Jan. 2020,

David Kretzmer, Professor Emeritus, Hebrew University of Jerusalem; Professor of Law, Sapir 

Academic College. I wish to thank Efrat Bouganim and Liron Odiz for their research assistance and helpful comments. I was fortunate to have had the opportunity of presenting this article as a paper at the NYU Institute of International Law and Justice Colloquium and at the Sapir College Faculty Seminar. Special thanks go to Professors Joseph Weiler and Gabariella Blum, students who participated in the Colloquium, and colleagues who participated in the Faculty Seminar for their insightful comments. Email: . “The Inherent Right to Self-Defence and Proportionality in Jus Ad Bellum.” European Journal of International Law, 1 April 2013. Accessed May 10, 2020.

Colonel Gary P. Corn*. “ARTICLE: Should the Best Offense Ever Be a Good Defense? The Public 

Authority to Use Force in Military Operations: Recalibrating the Use of Force Rules in the Standing Rules of Engagement.” Vanderbilt Journal of Transnational Law, 49, 1 January, 2016. Accessed May 10, 2020.

Paul H. Robinson * & Adil Ahmad Haque **. “ARTICLE: Advantaging Aggressors: Justice & 

Deterrence in International Law.” Harvard National Security Journal, 3, 143 2011. Accessed May 10, 2020.

Luis E. Chiesa* and Alexander K.A. Greenawalt**. “ARTICLE: Beyond War: Bin Laden, Escobar, and the Justification of Targeted Killing.” Washington & Lee Law Review, 69, 1371 Summer, 2012. Accessed May 10, 2020.

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