On Feb. 28, 2026, the United States and Israel launched a war of aggression against Iran, in clear violation of Article 2(4) of the UN Charter and customary international law, according to a consensus of international law experts with whom we agree. Iran responded with a series of unlawful attacks against States in the region.
In a piece published last week by Just Security, Professors Yuval Shany and Amichai Cohen suggested the U.S. and Israeli strikes against Iran, and the notably mild or even supportive response by certain western States, reflects a general dissatisfaction with international law on the prohibition on the use of force. They suggest that international law must change to accommodate such States’ frustrations if a viable international legal order is to survive. We disagree.
There is no doubt that there are systemic and structural problems with the international architecture to respond to States that transgress international law. Yet, the inference of a general dissatisfaction with the substantive rules of the U.N. Charter is unfounded. For the overwhelming majority of the 193 Member States in the United Nations, the prohibition on the use of force remains evidently in their interests. Many have made this clear, with varying degrees of directness, in their responses to the current war.
Shany and Cohen question whether third-party condemnations–many of which denounced both the U.S. and Israeli attacks and Iran’s retaliation–“necessarily reflect a principled analysis” of the law. Of course it’s fair to question the discrepancy between States’ public statements and true preferences. And yet, Shany and Cohen appear to presume the good faith of the violators and a handful of their allies. The reality is that there is no indication that the United States and Israel have taken these steps pursuant to a principled assessment that the law needs to be changed or that it is unfit for purpose as applied to States generally. They clearly appear to have violated the law because they think it should not apply to them. Supportive or equivocal allies are either too weak in the context of a U.S. president who uses overwhelming power to threaten and bully, or too enamored with the prospect of a desirable outcome in this case to stand in the way.
Quite apart from the legal outlook of the parties to the armed conflict, Cohen and Shany are also wrong to entertain the notion that this war exemplifies an understandable pursuit of extra-legal imperatives associated with legitimacy and self-preservation. Although they express reservations about both approaches, a full-throated refutation of those approaches is needed. We reject outright both ways of framing the U.S. and Israeli aggression and state responses to it.
For Shany and Cohen, to call out aggression in this context is to engage in “grandstanding” and “lecturing States on how to act without offering them credible solutions to their actual problems.” The truth is that the kind of “pragmatic reevaluation of international law norms and institutions” that they appear to advocate would most likely return humanity to the permanent scourge of war and open the floodgates to immense human suffering. To be clear, we do not write to diminish the gravity of this moment for the rule of law. International law is not self-enforcing; it is only as strong as the willingness of States to insist upon it being upheld. Its brazen violation and the failure of certain prominent States to flatly condemn that violation poses a profound challenge to the legal system. Plainly, that challenge merits scrutiny – just not in the way that Shany and Cohen propose.
A flawed premise
Shany and Cohen’s article rests on the premise that the United States’ and Israel’s aggression entails an understandable expression of frustration with the rules on the use of force given an international legal system that has failed to stop Iran’s many transgressions. On this telling, U.S. and Israeli operations to destroy Iran’s military and change or collapse its regime are principled law-breaking, a violation motivated by the need for a better system and state of affairs. They further suggest that failures to condemn the United States and Israel for violating the prohibition can be read as supportive of either the emergence of a new rule of customary international law or of an exception to its normativity. The former, they argue, would take the form of a new “self-preservation” carve-out to the prohibition on military force. The latter would manifest in a category of violations that qualify as legitimate, despite their illegality.
We unequivocally reject this premise. It is true that the formation of new customary international law often requires breaking an existing rule and seeing how other States react. But such action is done in service of advancing a new rule that applies, by definition, to all States. That is plainly not what the United States or Israel seeks. What happened here is simply that the United States and Israel violated the law. It misdescribes and, in turn, misdiagnoses the situation to claim otherwise.
This is obvious procedurally and it is obvious substantively. The United States and Israel did not seek, and would not have obtained, a nine-vote majority at the United Nations Security Council. They cannot claim they were stymied by an illegitimate use of the veto; they know they would not have received the votes necessary to pass a resolution even in the absence of a veto. They did not try to invoke the Uniting for Peace procedure or otherwise seek the support of the U.N. General Assembly. They did not seek the support or authority of any other appropriate international organization or, indeed, any organization at all. They acted alone. None of this is consistent with a restrained and principled effort to change the law through violation underpinned by widespread normative affirmation.
Substantively, neither the United States nor Israel have articulated an alternative legal doctrine of self-preservation or a principled basis for legitimately violating the law. After breaking the foundational rule of international law, they have not made the case that a different rule of customary international law should emerge. They have defined no doctrine that they would recognize as available to other States that might act unilaterally and aggressively in pursuit of their interests.
Quite the opposite, President Donald Trump has stated publicly that he doesn’t need international law, and that his power as Commander in Chief of the most powerful military the world has ever known is constrained only by his “own morality.” In no case has he suggested that all States should be allowed to go to war against those who they deem illegitimate, those from whom they perceive a threat, or even those who explicitly threaten them. If there is any proposed rule here it is that the prohibition on the use of force does not apply to the United States and select allies.
Any notion that the aggression is an act of principled law-breaking is further belied by how the operations have been carried out. U.S. Secretary of Defense, Pete Hegseth described a campaign involving “B-2s, B-52s, B-1s, Predator drones, [and] fighters controlling the skies, picking targets, death and destruction from the sky all day long” and in which at least 1,205 civilians are estimated to have been killed. Trump has forecast “complete destruction and certain death” in targeted areas. Hospitals, schools, and a desalination plant have been struck. Attacks on an oil depot have left residential areas of Tehran ablaze.
In short, the lack of engagement with multilateral processes, the failure to articulate a principled justification for the campaign, and the manner of its implementation are wholly inconsistent with the notion that this was the last resort of States that are generally committed to the law, but saw no path forward other than violating the rules in search of a new legal or ethical paradigm.
Ad hoc justifications for illegality
Ad hoc legal justifications are presumptively suspect, so we engage Shany and Cohen’s line of inquiry with serious reservations. That said, States have, for decades, debated both how narrowly or broadly to interpret the self-defense exception to the prohibition on the use of force, and whether there is space for a humanitarian intervention exception to the prohibition.
Aspects of Shany and Cohen’s argument sound in the register of these longstanding debates. But they ignore key throughlines and discrepancies that make neither exception a plausible feature of the current international developments with respect to the war with Iran. Operation Epic Fury and Operation Roaring Lion are manifestly illegal, constituting both a violation of the UN Charter and the international crime of aggression. Neither the operations nor some States’ muted responses provide the political or normative conditions for legal reform or a framework of legitimate law-breaking.
“Self-preservation”
Just over 80 years ago, the United Nations Charter solidified a shift in the way that States could lawfully respond to States that threatened them. Whereas previously the resort to war was understood by States to be a legitimate and lawful way of dealing with adversaries, the U.N. Charter set out to “to save succeeding generations from the scourge of war” by removing the threat or use of force from the lawful toolkit that States could unilaterally deploy against each other. The goal was not, however, to leave States as sitting ducks in the face of an actual or imminent armed attack, which is why the inherent right of States to act in self-defense was retained as an exception to the new prohibition. Neither were the drafters blind to the possibility that, even in the absence of an actual or imminent armed attack, States could behave egregiously toward other Member States. Thus they created another exception to the new prohibition in situations where a case could be successfully made to the Security Council that using force against a State would in fact advance international peace and security. In the face of a Security Council veto, it has been argued (plausibly in our view) that such a case could be made instead to the U.N. General Assembly, which could support such action through a Uniting for Peace resolution.
Shany and Cohen acknowledge the existence of these options, as well as the reality that the self-defense exception’s actual or imminent armed attack requirement does not cover any threat that Israel faces from Iran, and that neither the Security Council nor the U.N. General Assembly have been persuaded of the merits of using of force against Iran to maintain international peace and security.
Nonetheless, in observing the equivocal reaction of certain key western States to Operation Epic Fury/Roaring Lion, Shany and Cohen posit this may reflect tacit acknowledgement that the existing system is unworkable for States that perceive an existential threat. They go on to suggest that this may lead to the reemergence of “right to self-preservation” that frees self-defense from the strictures of the actual or imminent armed attack threshold. Indeed, such a right would far exceed even the most expansive interpretation of anticipatory self-defense—the so-called “last window of opportunity” conceptualization of imminence that has been advanced by Israel, the United Kingdom, and Australia. Not even the public statements of U.S. or Israeli officials indicate that they acted at the last moment before the window to prevent an inevitable Iranian attack would close.
Shany and Cohen write that they would view the development of a consensus that the existing system is unworkable for States facing an existential threat as “highly problematic.” And yet, they appear somewhat sympathetic to its application in this case and fail to articulate precisely how they themselves think international law should adapt. We do not believe that, when considering perspectives beyond those of a few powerful States, this moment signals anything close to broad State support for incorporating a doctrine of self-preservation. Indeed, we are skeptical that even those States that are engaged in, or tacitly supporting, the attacks on Iran would actually endorse this as a universal standard that might be applied in reverse. What absolutely has been happening since at least the U.S. 2003 invasion of Iraq, is a fluctuating effort across U.S. administrations to frame illegal or legally questionable uses of force as justified by an expansive interpretation of self-defense in ways that have weakened this keystone rule of international law. Still, we believe it is important to explain precisely how dangerous this latest line of argumentation is.
As noted above, the move, in the aftermath of two world wars, to restrict the unilateral use of force by one State against another, did not leave States without options for shaping the behavior of their adversaries. Beyond the use of force framework, the U.N. Charter era has seen a proliferation of unilateral, regional and international self-help tools that States can and do use to mitigate threats. These include economic, diplomatic, and other sanctions, travel bans, non-forcible cyber measures, exclusion from international organizations, noncooperation, and more. Strikingly in the current case, the United States unilaterally withdrew from precisely such a non-forcible mechanism for addressing the threat of Iranian nuclear proliferation, arguably contributing to the current situation in which the United States now claims a necessity to act.
Given the existing global distribution of military power, returning the prerogative to resort to war as a legally available option of States would, at most, benefit the handful of governments with the capability to project immense military power extraterritorially. Even for them, the benefits are highly doubtful. History counsels that while war reliably wreaks devastation, it is a very poor tool for achieving any policy goals that depend on the will and engagement of the people in the attacked States. Decisionmakers in powerful States might also consider whether even their military might will be sufficient to insulate them and their people from the calamity that would follow from a return to war as an ordinary tool for the pursuit of foreign policy interests.
Meanwhile, for most States that live under an existential threat—from Ukraine and Taiwan, to many of the States surrounding Israel and indeed even NATO Member States who have begun to think they can’t count on the United States—their best chance for survival turns on the support of an international community that is willing to stand up for the existing limits on the use of force. What is certain is that for the overwhelming majority of States, and for humanity as a whole, the consequences of ending the prohibition on the use of force would be cataclysmic.
“Illegal but legitimate”
The notion that a resort to force in violation of the U.N. Charter might be “illegal but legitimate” originated with NATO’s 1999 air campaign against what was then the Federal Republic of Yugoslavia. The (controversial) idea was that an operation tailored to the objective of preventing atrocities and ethnic cleansing in Kosovo could be legitimate despite clearly transgressing Article 2(4) of the Charter. This, along with the failure of the international community to stop genocide in Rwanda, catalyzed the effort to articulate the conditions under which a “responsibility to protect” might be invoked.
However, despite decades of advocacy, the notion that this doctrine would authorize military intervention to stop atrocities has received widespread State support only in relation to actions authorized by the U.N. Security Council. The paradigmatic example in that regard was the Security Council-authorized intervention in Libya in 2011. The long-term consequences of the intervention, with an ensuing civil war that has had a devastating impact on civilians, have diminished the normative pull of the “responsibility to protect” doctrine as the basis for resorting to force over the last 15 years.
Beyond Security Council authorization, the only scenario that has garnered sizable State support entails working through a relevant regional organization (see Article 4(h), African Union Constitutive Act), and even this has not been developed in practice. Finally, and much more controversially, a tiny minority of States, most prominently the United Kingdom, have asserted the right to resort to force to stop atrocity, even in the absence of authorization by the U.N. Security Council or a relevant regional organization. Key components of even this minority doctrine entail some form of multilateral affirmation and a strict requirement that the resort to force be narrowly tailored to the urgent humanitarian objective.
Notwithstanding the significant attention paid to the topic in academic and policy discourse, States have rarely pursued humanitarian intervention since the Libya operation. This is despite ample situations in which it would have been plausible, whether in Myanmar, Sudan, Yemen, Gaza, Ethiopia, or Syria (here, the limited U.S.-led military strikes in response to the Syrian regime’s use of chemical weapons, against the backdrop of 11 years of atrocities against Syrian civilians, marks the exception that proves the rule).
Whatever one makes of the “illegal but legitimate” concept in cases of narrowly tailored humanitarian intervention, it is implausible to try to fit the attacks on Iran into this limited tradition – either as a normative matter or as a scholarly description of what the operations and States’ reactions entail. There is little doubt that Iran has perpetrated crimes against humanity against political protestors in recent months (or that the Iranian regime has spent over four decades violating the human rights of its people). However, neither the United States nor Israel has articulated the mission in terms of atrocity prevention and the military operations are plainly not narrowly tailored to a humanitarian objective. On the contrary, they pose grave and expansive threats to the Iranian population.
Tellingly, neither the United States nor Israel has pursued any nonforcible mechanisms of atrocity prevention, sought any international endorsement to intervene, or even articulated a new doctrine of humanitarian intervention that would apply to all States. Yet Shany and Cohen suggest that having engaged in crimes against humanity, Iran might simply “cease[] to be considered, in the eyes of many observers, a legitimate international actor.” Given that neither the U.N. Security Council nor the U.N. General Assembly has sought to cast Iran outside the bounds of international law’s protections, the argument seems to be that intervening States garner the unilateral discretion to decide that other States lose the protections of international law. That this evaluation might be conditioned on credible reports of the State’s direct involvement in crimes against humanity is plainly not a standard to which either the U.S. or Israeli governments would subscribe, given credible reports of their own international crimes in, for example, Gaza and the Caribbean. Shany and Cohen suggest a State’s loss of status as a legitimate international actor might also be predicated on its threats to regional actors. But again, this does not appear to be a standard the United States or Israel would want to universalize given how readily such a standard could be invoked against them.
Ultimately, Shany and Cohen appear to settle on the notion that “the regime in Iran has lost almost all of its international credibility and support.” But this is no basis for asserting the legitimacy of unilaterally resorting to force against the isolated State. Politically, one would expect the bar for convincing other States to endorse the use of force to be at its lowest in relation to a regime that has few friends and has “lost almost all of its international credibility and support.” That even in such a case there was no effort to engage the Security Council (even to evince veto obstruction), no effort to engage the General Assembly under Uniting for Peace, and no effort to garner any other form of credible multilateral approval speaks volumes about the weakness of the argument for going to war. No such efforts were made because they would not have been successful.
In sum, it is difficult to see past the conclusion that their argument boils down to a single and disturbing outcome: that “tacit support given by many Western States” can, in essence, legitimate aggression.
The real issue
The regime governing the resort to force is imperfect. For civilians under attack by States with a Security Council veto or a veto-wielding ally, be they in Gaza, Myanmar, Sudan, Syria, Ukraine or elsewhere, the limitations of the current system have long been clear. For those populations, Shany and Cohen’s concern about the systemic failure of the Security Council resonates with particular urgency. But the nature of that failure inheres in the veto—a mechanism upon which one of the aggressors in this war has relied frequently, often to shield the other.
The path to an international law and international institutions that are more responsive to genuine security concerns, be they existential or humanitarian, is through either reforming the Security Council, or reviving Uniting for Peace and the use of the General Assembly as a forum for addressing such issues when the Security Council is deadlocked by veto. More could also be done to empower regional organizations. Whatever one’s view on the optimal path to reform, it must be multilateral and it must take seriously the security concerns of all States, rather than only the small handful with extraordinary military might.
The stakes could not be higher. The prohibition on the resort to force in international relations is the keystone of the contemporary international legal system. If it were to fall into desuetude, the consequences would be felt first and foremost in the catastrophic human toll of war. Beyond that immediate implication, it would also call into question the viability of international law across the board. The current framework of international law is predicated on the notion that States enjoy territorial integrity, political independence, control over their natural resources, and the ability to enter and exit agreements that operate on the basis of peaceful dispute resolution. None of that can be presumed in a world in which might makes right.
In this respect, the failure of key western States to condemn the strikes on Iran is extremely alarming for the health of the international legal order. International law is, by definition, applicable to all States. If certain States continue to condemn violations of international law only by States they see as adversaries or less powerful, while giving (particularly their more formidable) allies a free pass to commit brazen aggression, international law will ultimately cease to function altogether.
