Peter Hilpold (Università di Innsbruck; Università di Pavia)

Fault lines in the US/Israel intervention in Iran

The large-scale military strikes launched by the United States and Israel against Iran, starting on February, 28, 2026, triggered not only a devastating war but also turmoil in the international law academy, resulting in a flurry of condemnations (see i.a. here, here, here and here). At the same time various attempts, albeit minor in number, can be noticed, to justify this attack or at least to balance some pros and cons, while eventually speaking out against these measures.

For many, these events seemed to confirm the assessment, repeatedly heard in the last time, that “international law is dead,” that the prohibition of force has collapsed into mere rhetoric, and that the Charter’s collective security design has become a façade. In the following, it shall be assessed, whether such a gloomy outlook is justified and what is really at stake here. As to the long-term resilience of the basic achievements made by the UN order perhaps the situation is not so worrying. It might rather be the case that the present crisis has again brought to the fore some basic limitations of international law that are often ignored.

This contribution does not take sides for one of these camps. International law is not dead but rather an imperfect order continuously trying to find a new balance in its aim to fulfill at least some of its high-standing aims. 

Disorder, uncertainties and lacunae do not mean that international law would be moribund or dead. Contestations in doctrine are the best sign that the discipline is alive and well. The fact that both critics and defenders speak the same language, even when attributing a partly different meaning to the terms used, is evidence of the fact that international law remains the shared vocabulary of legitimacy. It still offers a common forum where conflicts can be borne out about in a structured way (see on this M. Koskenniemi, What is International Law for?, in: M. Evans (ed.), International Law, 6^th ed. 2024, pp. 29-52, p. 47ss.), with aims and objectives ever more demanding, while the means to achieve them remain scarce and often elusive.

Imminence and the limits of preventive or anticipatory self-defence

The US/Israel attack on Iran was justified, first of all, by the need of self-defence against the Islamic Republic of Iran, which has repeatedly sworn death to Israel and the USA and has been committing terrorist attacks against these two states and their citizens for many years. This prompts, however, the question, whether such facts unleash the right to self-defence, which, as an exception to the prohibition to use force on the basis of Art. 2 (4) of the UN has to be interpreted restrictively. Summarizing the result of a broad discussion led already in the past, it can be held that the prohibition of force, despite its shortcomings, remains, in general, a better protection for the weak than a more permissive regime that might invite abuse by the powerful. Admittedly, however, such a principle will lead in many cases to unsatisfactory results.

The classic formulation most often invoked as the customary-law benchmark of anticipatory self-defence can be traced back to the so-called Webster of 1841: necessity must be “instant, overwhelming,” leaving “no choice of means” and “no moment of deliberation,” with proportionality confining the response to what necessity demands. Even in legal cultures willing to accept also measures of preventive or anticipatory self-defence, the requirement of imminence is the key factor of differentiation, meant to prevent the right of self-defence from mutating into a discretionary license for preventive war, thereby operating as a gateway to transform the exception to an easily accessible rule.

This discussion is not merely of an academic nature. It has been at the core of the attempts to reform the UN in the early 2000s.

In parallel, attempts were underway to overcome the human security gap made evident by the crimes of genocide in Rwanda 1994 and in Srebrenica 1995 and the mass-killings and crimes against humanity in Kosovo 1999. All these events revived a traditional conundrum of modern international law: the conflict between the desirability of intervention in exceptional situations where the survival of large parts of a population is at stake due to the repressions by the government while at the same time upholding the imperative need to stick with absolute prohibition of the use of force according to Article 2 (4) of the Charter.

Efforts to overcome these deficits and lacunae in international law led to a process of several steps, eventually resulting in the introduction of the concept of the “Responsibility to Protect  R2P”. Its adoption by the World Summit of 2005 was ground-breaking and yet, the Outcome document contains a R2P concept which has been water-down in essential parts in respect to the previous proposals.

This holds especially true with regard to the initial document on R2P, prepared by the International Commission on Intervention and State Sovereignty (ICISS) of 2001 which clearly spoke out for the permissibility of unilateral intervention. In 2000, the then UN General Secretary Kofi Annan, wondered the following in para. 31 of his report “We the people”:

“If humanitarian intervention is, indeed, an unacceptable assault on sovereignty, how should we respond to Rwanda, to Srebrenica – to gross and systematic violations of human rights?”.

The UN General Secretary continued to sponsor the idea of R2P also in the following, arguing also for a right to (multilateral) humanitarian intervention which should find application on a broader scale by rendering multilateral decision-making within the SC more effective.

Unlikely as it might have seen in advance, in para. 138 and 139 of its Outcome Document the UN World Summit of 2005 approved the R2P concept, however in a “lite” version, upholding the restriction of the use of force set out in the Charter with no exception for measures of unilateral humanitarian intervention. New ground was broken in the sense that from now on the SC could authorize the use of force also in case of widespread human rights abuses occurring within the boundaries of one single state, but the reforms did not extend to much more. The question of what should happen in case of human rights abuses with the Security Council unwilling or unable to act remained open.

With the far-reaching plans for a UN reform having stalled, also the question whether anticipatory or preemptive self-defence should become permissible, as most famously the US Bush administration has argued for in its National Security Strategy of 2002 in the immediate aftermath of the Twin Towers attack of 2001, remained unaddressed.

The politics of context: existential rhetoric, cumulative threats, and the temptation of preventive war

In the context of the 2026 military operation against Iran (and even more so in regard to the operation “Rising Lion” of summer 2025, against Iranian nuclear infrastructure and ballistic missile capability) justifications for these attacks, as far as they relied on self-defence, tended to emphasize “context” rather than immediacy: Iran’s long-term strategic posture, its missile and nuclear programs, its network of regional partners, and its repeatedly voiced fundamental hostility toward Israel that was framed as an existential threat for this country. Justification seemed thereby to shift toward “contextual imminence” of the threat or to a “cumulative threat”.

There is surely some value in the argument, already pronounced in detail in the NSS of 2002, that since 1945 (and even more so since 1841, when the Webster formula was crafted) warfare and warfare technology have changed so dramatically, with the development of high-speed weapons of mass destruction which are hard to intercept, that self-defence, should it remain meaningful and effective, would have to be permissible in a far broader context and on an earlier stage when an armed attack is conceived and planned.Nonetheless, most reactions to the attack of February 2026 on Iran reveal that neither academia nor the state community is willing to abandon the altogether exceptional character of self-defence according to Art. 51 of the UN Charter in its traditional fashion. The question must therefore arise whether academics and governments, sticking to this traditional vision of self-defense, are either ignoring or accepting the circumstance that the development of modern military capabilities is eroding to a considerable extent the possibility to take recourse to the “inherent right of individual or collective self-defense”. And are they perhaps also cynically oblivious to the suffering of the persecuted and downtrodden?

Humanitarian intervention, R2P, and why the Security Council monopoly survived

As mentioned above, the second justification voiced for the military intervention in Iran touched upon a concept that has often been called as “humanitarian intervention”. While military interventions authorized by the SC to save human lives in case of widespread violence are now, especially after the adoption of the Outcome Document of 2005, to be recognized as legitimate, the real problem lies with so-called “unilateral” measures of humanitarian intervention, i.e. military interventions not authorized by the SC, be they carried out by a single state or by a group of states. Such measures are still to be considered as contrary to international law. As shown, neither genocide nor mass-killings in Srebrenica, Rwanda and Kosovo, evidencing the urgent need for forceful help from outside in such extreme situations, has led to a change in the relevant international law provisions. R2P allows the SC to act, but if this body is paralyzed, especially due to discord between the permanent members, no help can be provided to persecuted people with military means. In its Advisory Opinion of 22 July 2010 on Kosovo the International Court of Justice (ICJ) refrained to deal with this delicate issue. In the past, there have been repeated attempts to argue otherwise and to posit that there is either a right to humanitarian intervention in the most extreme cases or a related right to “remedial” secession for peoples suffering such forms of persecution. While these theories are built, in many ways, on morally appealing arguments, they eventually fail to convince on the legal level.

Nor did the Kosovo intervention of 1999 by NATO states legalize humanitarian intervention. To the contrary, this intervention, as morally justified as it might have been on humanitarian grounds, is often cited as a dangerous precedent potentially eroding the prohibition of the use of force according to Art. 2 (4) of the UN Charter while not being able to provide a new, generally recognized rule in this field. On this basis it seems reasonable to argue that we are facing a serious gap in international law according to which this legal system misses out on basic needs of human beings in situations where help is most needed.

 “And with success, comes pardon hand in hand”

The crimes committed by the Iranian government and the Revolutionary Guards are well-documented and happened over decades. The repression of the mostly peaceful protest in January 2026 was outrageous as to the cruelty and the brutality of the methods used. Should reactions by third states be confined to protests, or perhaps to economic or individual sanctions of dubious efficacy?

There can be no doubt that such restraints, imposed by international law, make help for victims of such crimes mostly futile or impossible and this highlights an enormous gap in international law which is, however, not new.

Even after 1945 there have been several “unilateral” military interventions which can be characterized, at least partly, as “humanitarian”. According to international law they were illegal and the best the intervenor could hope for was that the state community would not condemn this action or even abstain from applying sanctions. Not always these hopes were fulfilled. 

A paradigmatic illustration of this problem is given by Vietnam´s intervention in Cambodia in 1978-78 against the murderous, genocidal regime of the “Khmer Rouge”. This intervention probably saved millions of lives by removing the Khmer Rouge terror regime, but nonetheless Vietnam was not praised by the community of States, but rather had to suffer further sanctions, especially by Western countries.

As often said, no humanitarian intervention in international law has been motivated exclusively on humanitarian grounds, but nonetheless, what counts, one may argue, is the effective help provided to the oppressed.

As to the present intervention by the USA and Israel in Iran, a broad range of motivations can be identified and it is by far not clear what are the prevailing ones. Let´s not make any mistake: if international lawyers condemn this action, they are doing their job in defending the most pivotal rules of our modern international law order. To argue for a return to the “just war” era, even if justification would be sought for mainly or exclusively in the protection of human rights, is no viable alternative as history has sufficiently evidenced how the just war doctrine is prone to be abused to justify all kinds of abuses and practically any sort of war.

The dilemma is palpable: The dangers posed by Iran for the whole region, its sponsoring of terror and the blatant defiance of Iran´s rulers of their own people´s human rights were a matter of fact, while, for good reason, there is no preparedness in the state community to abandon the Webster formula. (Unilateral) humanitarian intervention is illegal and it should remain so in the view of the dangers the abandonment of the prohibition of the use of force poses. The “kind-heart gunmen” (see Ian Brownlie, ‘Thoughts on Kind-Hearted Gunmen’ in Richard B Lillich (ed), Humanitarian Intervention and the United Nations, University Press of Virginia, 1973, pp. 139–148) is anathema to human rights lawyers as a matter of principle.

As argued elsewhere, however, the overall picture in international law is broader. Now and then, help is provided also unilaterally, without UN authorization. In such cases, widespread condemnation by the state community looms. This reaction may be motivated, like the intervention itself, by spurious motives, but on a whole, it helps to uphold the rule, the prohibition of the use of force, which is, as stated, of paramount importance for maintaining the modern international order, imperfect as it may be.The intervener can hope, albeit without any sort of guarantee, that the more its motives of intervention are genuinely humanitarian and sincere, the less the state community will sanction its breach of international law. Adopting a utilitarian perspective, governments might approve the termination of widespread human rights abuses, if only this contributes to stability. One decisive factor for the eventual acceptance of an intervention is success. As already Friedrich Schiller wrote in “The Death of Wallenstein”: “And with success comes pardon hand in hand.” Both lawyers insisting on the uncompromising defense of the existing international legal order as those arguing for broader exceptions in the face of existential threats for individuals, peoples and nations can contribute to a definition of “success” that might be reconcilable in the best possible way with a less than perfect international legal order.