On the Killing of Enemy Sovereigns 

The killing of Ayatollah Khamenei in a joint Israeli–American military strike last month raises questions both general and specific. Generally: are there circumstances, and if so, what are they, in which it is morally permissible for one (or more) country to target the ruler of another for death? Specifically: was this killing justified? And if not (as I will argue), on what grounds did it fall short? I begin with the general question, approaching the issue from the standpoint of natural law theory. 

Consider first the killing of a foreign leader during peacetime. The natural law tradition acknowledges only two forms of justified killing of such a person: one is as a form of punishment carried out by those with appropriate authority; the other is as a form of self-defense or defense of another. Both are historically encompassed by that strand of natural law theory known as just war theory, to which I will return below. The question for now is whether either form of justification is available for the targeted peacetime killing of a foreign sovereign. 

Fidel Castro, for example, stood in a posture of ideological hostility to the U.S. and was seen as dangerous, a rogue actor in league with our enemy, the Soviet Union. He was therefore thought by the Kennedy administration to be worth getting rid of by lethal means, even though the U.S. was not, in fact, at war with Cuba. The United States, either through its intelligence agencies or by high administration approval (or both), made several attempts on Castro’s life, including one attempt by means of a poisoned cigar. 

If those attempts were motivated by the thought that the world would be a better place without Castro or that U.S.–Cuba relations would thereby be improved, or by any of the various ends, such as trade, that diplomacy might have been utilized to accomplish, then it seems to me that such efforts were simply wrong: none of these rationales can be understood as either punitive or defensive, and so, as ends to be sought by the use of force, they fall short of justifying the attempts on Castro’s life. 

Could such an attempt in peacetime be a legitimate form of punishment? Castro was surely guilty of much wrongdoing. But—and we will return to this difficulty—by what authority could the U.S. pass sentence and carry out execution? Castro was neither a U.S. citizen nor in a jurisdiction of the United States; nor did the U.S. and Cuba stand together under the authority of some supranational legal entity. Such an extra-legal form of capital punishment is surely unjust in the natural law tradition. 

Nor were attempts on Castro’s life plausibly understood as forms of defense of the United States. No doubt they were thought to be in defense of the interests of the United States, including the U.S.’s strategic interests. But a threat to such interests is insufficient to justify a lethal response; the threat envisaged by natural law and just war theory is a threat of force against the lives and well-being of the nation’s citizens (or, in certain humanitarian interventions, the lives of another nation’s citizens, a possibility I will return to later). Thus, much U.S. action against Cuba, which included not just assassination attempts but also an attempted invasion and a long-running attempt to destabilize the country, seem to me to have been morally wrong. 

So the killing of foreign leaders during peacetime seems generally impermissible. The question remains, however, whether it might be permissible within the framework of just war theory when two nations are at war. 

Let me address one way such killing would, I think, be impermissible, namely, if carried out as a form of punishment for past wrongdoing. In its classical form, just war theory did in fact accept the legitimacy of such uses of lethal force. When Aquinas speaks, for example, of a just cause as needed for war, he seems to have in mind primarily a cause of legal action that has as its consequence that the enemy deserves to be warred upon, in consequence of some past wrongdoing. 

Were that correct, then it could certainly be justifiable, in general, or in the particular case of the ayatollah, to bring death as a form of punishment, since many nations’ leaders (and certainly Iran’s) are guilty of grave crimes against humanity. 

But the natural law tradition, in what I consider its most important twentieth and twenty-first century voices, including those of recent popes, has abandoned punishment as a just cause for war. 

This abandonment is warranted for the reason I articulated against treating assassination as a form of capital punishment in peacetime: in the absence of a genuine world government, few, if any, nations are under a common forms of authority that may legitimately pronounce and carry out capital sentences. Certainly, the U.S. and Iran do not stand together under such a mutually acknowledged authority. And so the United States simply lacks the authority to carry out acts of war, including targeted killings, as forms of punishment—even on those whose crimes are grave. 

The remaining general question, then, is whether a country, engaged in a just defensive war, might be morally justified in targeting the leader of the country with whom it is rightly engaged in hostilities. Is there some reason to think that the sovereign of a foreign nation—with whom another country is justly contesting by arms—is immune from the force used by the rightly contending nation? Should that nation limit itself to attacks on the soldiers of the country with whom it is at war? 

I can think of no principled reason why this would be the case. Prudential reasons are not impossible: perhaps the enemy country would be thrown into such chaos and disorder were its supreme leader killed that the resulting threat to peace would be disproportionate to the military gain. That would be a reason, and sometimes an overriding reason, not to target the foreign leader. 

But a country’s leader is the ultimate head of its military and thus may rightly be seen as the source of the threat to which a justified response is being made. If there is reason to think that responding to the threat at its source would significantly promote the ends of defense against attack, and ultimately, peace, then that is a good reason, and on some occasions a sufficient reason, to do so. It seems implausible, for example, to suppose that it would have been morally permissible for Colonel von Stauffenberg to plot an assassination on Adolf Hitler, but wrong for the Allies to do the same. 

The claim that, as part of a just war of defense, the leader of the aggressing nation may be killed helps resolve a worry that might be raised about my treatment of peacetime killing. For, one might object, doesn’t just war tradition permit a subjugated people to overthrow a tyrant? And if the people may overthrow the tyrant, might not a foreign country come to their aid, permissibly eliminating at the source the cause of a people’s suffering? 

That seems plausible. But it seems to me that such humanitarian intervention is best understood as part of the theory of just war, and not, as I was discussing earlier, the use of forceful means during peacetime to achieve other political ends. In any event, there is a strong claim that in defense against significant attacks on life and grave violations of human rights, it is, in principle, permissible to use lethal force against a foreign leader. 

There are important questions of intention here, that for my purposes in this essay I will largely set aside. In the account of natural law and just war theory that I think true, an account that seems clearly endorsed and articulated in the Catechism of the Catholic Church’s treatment of war in sections 2307-2317, war can, as I have said, only be carried out for defensive purposes. 

But war must also be carried out in a way compatible with the fifth commandment which, according to the Catechism, “forbids the intentional destruction of human life.” I believe that certain acts of war can meet both the defensive and the no-intentional-destruction requirement (a position I argue for in my forthcoming Killing and Christian Ethics). Here, I assume for the purposes of argument that the same is true of the use of force against an enemy leader. 

But did the killing of Ayatollah Khamenei meet the necessary conditions for it to have been a justified use of force against the leader of a nation with whom we are justly at war? 

It should be clear from the argument thus far that a necessary condition for the just killing of the leader of a nation with whom we are at war is that we are indeed fighting a just war. And the grounds on which to doubt this are, as Edward Feser recently argued, numerous. 

This war does not appear to be genuinely defensive against an imminent threat; it is rather undertaken to prevent a threat that might, at some time in the future, materialize, and is therefore a “war of choice.” Natural law just war theory acknowledges no such category: justified warfare is always a matter of necessity. 

Nor does this war seem to be carried out with anything like right intent. The following points may suffice here to make this clear. The name “Epic Fury,” seems, in fact, to describe Defense Secretary Hegseth’s motivations accurately. According to a recent New York Times story, the goal of the war according to Hegseth is 

to unleash “death and destruction from the sky all day long.” Instead of seeking justice, U.S. forces are pursuing vengeance against an implacable foe. “Their war on Americans has become our retribution,” he vowed. 

Such a set of attitudes and intentions is deeply incompatible with the ultimate purpose of war and peace; peace understood not simply as a cessation of hostilities, but as the tranquility of order, a peaceable ordering of wills. 

Nor is President Trump’s demand for unconditional surrender compatible with right intention; it is indicative of a will to subjugate and humiliate. And neither, finally, is the evident lack of concern or planning for how and when the war might reasonably be brought to a conclusion compatible with an upright intent. Such fecklessness when our military action will bring about grave human suffering is deeply wrong.  

And this means that everything done in service of this unjust war is itself morally flawed. No doubt some of what is done is done non-culpably by soldiers or their leaders who believe themselves justly authorized to fight. But objectively, what is done in service of an unjust war is itself unjustified.  

It is thus a matter of the gravest possible moral urgency that the ultimate war-making public authority—in this case, President Trump—demonstrate with clarity why those, such as Feser, or various cardinals of the Catholic Church, or other just-war critics of this war, are wrong, by indicating the precise purposes for which he commenced these hostilities and by which they are justified. For in the absence of such clarification and justification, none of the ranks can responsibly follow orders to engage in these hostilities. 

Absent that clarification and justification it likewise follows, of course, that the killing of Khamenei was morally flawed. What might in some other case be a reasonable means of prosecuting a just war here shares in the corruption found at the root of this administration’s latest act of military and moral adventurism. 

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