A momentous gap has emerged between the broad consensus among international lawyers regarding the illegality of Operation Epic Fury (or Roaring Lion) launched by the United States and Israel against Iran on Feb. 28, 2026, and the mild or even supportive reactions afforded to the operation by many States.
While part of the gap can be explained by notions of political affinity to the United States and hostility toward Iran, and by reference to Iran’s own unlawful reaction to the attack (under both jus ad bellum and jus in bello), we believe this gap may also be indicative of a more fundamental crisis afflicting the international rule of law (or the rules-based international order (RBIO)): a growing perception among policymakers that international law no longer offers a workable framework of norms and institutions for addressing the most serious problems of international peace and security.
In this contribution we discuss two normative frameworks of analysis that may emerge as alternatives to the existing rule of international law – the “illegal but legitimate” framework that accepts that, in some circumstances, legal violations may be nonetheless ethically justified, and the “right to self-preservation” that suggests that international law (or standard international legal rules) cannot prevent States from protecting themselves against existential threats. Before discussing these two normative frameworks we will briefly address the international law analysis of Operation Epic Fury/Roaring Lion, State reactions thereto and their implications for the future trajectory of international law.
International law analysis of Operation Epic Fury
In the days since the beginning of Operation Epic Fury (referred to in Israel as Operation Roaring Lion), a broad consensus appears to be building among international lawyers that the operation exceeds the scope of permissible self-defense under Article 51 of the UN Charter, since neither Israel nor the US were victims of an actual or imminent armed attack (see e.g., here, here and here). Even Michael Schmitt, who was open to consider that the June 2025 Israeli military operation against Iran (Operation Rising Lion) could qualify as a form of lawful anticipatory self-defense, opined with two colleagues before the start of the current operation that no similar justification now exists.
At the time, we were of the view that Operation Rising Lion did not meet the imminence requirements; however, we did consider the operation to form part of an ongoing seven-front war (or, to put it in more technical terms, an operation forming part of Israel’s right to self-defense against an ongoing armed attack), by virtue of Iran’s substantial involvement in acts of aggression undertaken by its armed proxies in the region against Israel on and after Oct. 7, 2023. Based on Israel’s official legal position with respect to the targeting of Ayatollah Ali Khamenei, it seems that Israel’s view is that the legal situation remains essentially the same as it was on June 13, 2025: “The strike was conducted within the context of an ongoing armed conflict between Iran and Israel.” A more detailed articulation of this view might run as follows: while direct active hostilities between Israel and Iran in June ended on June 24, Iran made subsequent statements and continued to take military measures that revealed an intent to resume the fighting at will, including – as Prime Minister Netanyahu claimed – robust measures to renew its nuclear and ballistic programs in new and non-targetable sites. Iran also continued to provide support to its proxies and to engage in cyber-attacks against Israel. Hence, Israel appears to maintain that the original Iranian attack it confronted in June was still ongoing and that new measures taken by Iran presented Israel with a “last window of opportunity” to strike. If any legal claim were to suffice, these claims, involving elements of an ongoing attack, necessity and anticipatory self-defence, would appear to be the strongest.
This presumed Israeli position though does not seem to take into account the ceasefire understandings reached between Israel and Iran on June 23, 2025 and the more formal agreement reached between Israel and Hamas on Oct. 9, 2025 (Israel and Lebanon reached a ceasefire deal on Nov. 27, 2024 relating to Hezbollah operations). While these ceasefires are certainly brittle and all parties seem to ignore them from time to time, they did result in an end or sharp decline in major hostilities across all fronts, rendering it more difficult to refer to Iran and its proxies as still engaged in acts that meet the international definition of aggression or armed attack. The Israeli position also seems to downplay the significance of what we consider to be another notable change in circumstances – the fact that, according to all accounts, Iran’s nuclear program was “rolled back” in time in June, and that therefore the imminence of the nuclear threat, which in our previous analysis we considered to be an important factor in evaluating the necessity and proportionality of Operation Rising Lion, has diminished (although, obviously, both nuclear and ballistic threats did not disappear altogether and remain a serious problem). It seems to us that these factual changes render it harder than before for Israel to justify its new military operation under prevailing interpretations of jus ad bellum (including conditions of necessity and proportionality).
Another possible claim – which we have not seen being made yet by Israel – is that Iran’s rush to replenish its ballistic missiles and renew its nuclear program violated the terms of the June 23, 2025 ceasefire. While Israel’s interest in maintaining its military achievements from Operation Rising Lion is clear, we do not have before us information suggesting that Iran has undertaken any legally binding obligations to that effect (putting aside the additional legal question whether a violation of such undertakings constitutes, in effect, a casus belli under international law).
Whatever the legal position is regarding the justification for the Israeli attack, it seems that the justification for the U.S. attack – independently from a collective self-defense claim built on the Israeli self-defense claim – is even more tenuous. Maintaining a right to self-defense for the United States under the current circumstances requires the adoption of a very loose reading of what constitutes an ongoing armed attack or what constitutes imminence. Mike Waltz, the US Permanent Representative to the UN, seems to have argued the former position. In his statement in the UN Security Council on Feb. 28, he referred to the 47-year history of the Islamic Republic’s open hostility to the United States and its heavy involvement in international terrorism as a series of armed attacks. President Donald Trump seems to have based his claims on the latter alternative however, when he asserted that “they [Iran] were going to attack first,” though in his first public remarks on Feb. 28 he more closely tracked Ambassador Waltz’s framing. Secretary Marco Rubio, in an initial statement (which he has since walked back), seemed to have suggested yet a third possible line of justification for U.S. action, claiming that the United States may have been influenced by an imminent threat of retaliation against US forces if Israel were to attack Iran on its own (for an analysis of the legal problems with this third claim and its factual implausibility, see Lieblich). Notably, the White House “War Powers Report” to Congress on Mar. 2 makes no reference to an imminent attack.
A relatively forgiving international reaction
Despite the emerging scholarly consensus on the unlawfulness of Operation Epic Fury/Roaring Lion, many Western nations reacted to the U.S.-Israeli operation with varying degrees of support. Canada and Australia expressed outright support for the operation within hours, as did other countries, like Ukraine, Albania, and the Secretary General of NATO. Several states – like Germany, Japan, the Netherlands and New Zealand – refrained from passing judgment on the legality of Operation Epic Fury, but expressed support for the political aims of the United States and Israel and strong opposition to Iran’s recent behavior.
Indeed, consider the reactions of Western States that have a reputation for taking international law obligations seriously:
● Germany’s Chancellor Friedrich Merz said:
“Categorizing the events under international law will have relatively little effect. This is especially true when these classifications remain largely inconsequential. Over the years and decades, appeals from Europe, including Germany, condemning Iran’s violations of international law, and even extensive packages of sanctions have had little effect. This is also due to the fact we were not prepared to enforce fundamental interests with military force if necessary.
Therefore, this is not the time to lecture our partners and allies. Despite our reservations, we share many of their goals without being able to actually achieve them ourselves.”
● Netherlands Foreign Minister, Tom Berendsen said:“I also want to be honest that international law isn’t the only framework you can apply to this situation. You also have to be realistic, given the murderous nature of the Iranian regime.”
● Belgium Foreign Minister, Maxime Prévot said:
“As a defender of international law, Belgium must acknowledge that the way in which this operation was conducted does not comply with the norms,” but “must be weighed against the principle of reality;” that “we cannot say that Iran is a model student” of international law, and the U.S.-Israel operations are “justified for global security;”● Belgium’s Minister of Defense Theo Francken said the U.S.-Iran operations are “absolutely justified” and reportedly: “The question of whether the attack is in line with international law is for lawyers to argue, he said. Though he supports international law, he says it does not work in practice. The Iranian regime is able to do what it wants.”
The first EU country that spoke strongly and explicitly against the operation was Spain. Italy has since joined it in rejecting the legality of the operation, while France criticized the legality of the operation, but blamed Iran for the overall escalation. The EU has said it stands in solidarity with Spain, but that appears to be in response to President Trump’s threat to sanction Spain for its legal posture.
As can be imagined, outside the West, reactions have been more critical. Whereas China and Russia condemned the operation outright, the African Union condemned both the U.S.-Israeli operation and the Iranian reaction. Positions on the operation expressed at both the UN Security Council and Human Rights Council by other countries were mixed. In all events, one cannot assume that positions taken by states in diplomatic contexts necessarily reflect a principled analysis of jus ad bellum. For example, some States that condemned Operation Epic Fury did not condemn, in real time, the Russian “Special Military Operation” in Ukraine in 2022 (see e.g., here and here).
Possible explanations for the gap: Collapse of the RBIO and return to “illegal but legitimate”
How can one explain the significant gap that opened between the epistemic community of international law scholars on the one hand and the community of diplomats and political leaders on the other? One pessimistic explanation, which builds upon the depressing speech of Chancellor Friedrich Merz in Munich (Feb. 13, 2026) is that the rules-based international order (RBIO) is now defunct – i.e., that international law no longer plays an important role in the conduct of international relations. If this is indeed the case, we may be back to a Cold War-dominated vision of international law as epiphenomenal in nature, and of the Charter’s use of force provisions as effectively dead. This narrative of decline of the international rule of law appears to be correlated with processes of decline in the domestic rule of law in some countries and the rise therein of political populism, which rejects the authority of “global elites.” Such a narrative is also linked to what Secretary Rubio in his own Munich speech (Feb. 14, 2026) alluded to as the inability of the UN to resolve key international peace and security problems, and to the abuse of the language of international law by powers hostile to the West.
If international law norms and institutions cannot deliver peace, security and justice, then it is not surprising that they are increasingly regarded as useless – and, at times, counter-productive. Indeed, one could suggest that had the UN Security Council acted diligently against the Iranian regime’s long-standing policy of pursuing non-conventional weapons, exporting terrorism and creating a “ring of fire” around Israel, the attacks against Iran would have never taken place. Sentiments about the ineffectiveness of the UN-led order in resolving international conflicts may also explain why States are looking for solutions beyond international law (the statements above by Germany, Belgium, and the Netherlands are instructive). It also explains the creation of alternative international institutions more centered on power than on law, like the US-led Board of Peace.
While we agree that the RBIO is in deep trouble for some of the reasons mentioned above, we also believe that the forgiving approach taken by large parts of the international community toward Operation Epic Fury cannot be explained only by reference to cynical global power calculations and a reluctance on the part of world leaders to upset the U.S. President (although that may be part of the story as well). Rather, it appears to us that the Iranian regime ceased to be considered, in the eyes of many observers, a legitimate international actor after it brutally massacred many thousands of anti-regime protesters in January 2026 – international crimes which have been condemned broadly (but not universally). What’s more, Iran’s threat to retaliate against its neighbors if attacked (a threat which it promptly acted upon after Operation Epic Fury commenced) further eroded its international legitimacy. These perceived violations of international law by Iran (for an analysis of the illegality of the Iranian retaliation, see Milanovic) have consolidated international positions that the Iranian regime constitutes an unacceptable threat to security in the region, as well as a danger to its own citizens. This arguably led the President of the European Parliament, Roberta Metsola to state that: “International law is sacred, but it cannot be used to defend or justify a bloody dictatorship like Iran, which kills its own people and destabilizes the entire region.” Such perceptions pile upon long-standing concerns about political repression in Iran, and the threat it poses to the entire Middle East through its efforts to procure nuclear weapons, to export terrorism, and to develop and deploy an army of proxies.
The possible contribution of recent events in Iran to the forgiving attitude toward Operation Epic Fury means that we may be witnessing another iteration of the “illegal but legitimate” approach to the use of force. This approach helped to shape, in the past, international positions toward other military interventions which did not have a solid basis in the UN Charter, such as the Kosovo operation, the enforcement of “red lines” regarding chemical weapons in Syria, and ECOMOG’s intervention in Liberia and then Sierra Leone. In all such cases, the alleged justness of the cause of the force-using States and the unjust nature of the regime on the receiving end led many countries to support military interventions despite there being serious doubts surrounding their legality (in the ECOMOG cases, the Security Council retroactively blessed them).
Arguably, in the present case, the tacit support given by many Western States to Operation Epic Fury follows a similar line of reasoning: Preventing Iran from acquiring non-conventional weapons, containing the threat that it poses to the region, and creating conditions for a new government are all considered just or acceptable causes, whereas the regime in Iran has lost almost all of its international credibility and support. Under those conditions, an operation that retains some vestige of legality – in that it speaks the language of anticipatory, ongoing and/or collective self-defense, albeit in a questionable manner – enjoys political support despite its failure to satisfy the legal requirements under the law of self-defense.
Note that the implicit resort to an “illegal but legitimate” line of reasoning does not suggest a wholesale repudiation of international law, but rather reveals a willingness to read jus ad bellum norms flexibly and alongside other important international law norms which constitute part of the peace and security architecture of the Charter: human rights, non-intervention, prohibition of the threat of use of force, non-proliferation of nuclear weapons, ban of support for terrorism etc. At a time when the Security Council is unable to meet its responsibilities to maintain peace and security, it is not surprising that some States consider that “taking the law into their own hands” is the only way to uphold the values underlying the Charter.
To be sure, international law scholarship has been critical for very good reasons of the “illegal but legitimate” approach to the use of force, noting that reliance on subjective morality to justify deviations from legal obligations puts in question the very notion of an international rule of law (as President Trump himself explicitly questioned when recently asked about his interest in international law). This is because what is morally justified or even required in the eyes of one State leader, may be deemed immoral in the eyes of another. By contrast, international law is supposed to offer a sufficiently precise and common language that reflects practical agreements about morality, shared interests, and institutional considerations.
Still, identifying gaps between how positive law is applied and moral considerations is valuable, as it may enable the evaluation of existing international law norms and institutions and facilitate calls for their reform in appropriate cases (see e.g., Ku and Blackett). In the present case, Operation Epic Fury exposes the long-standing failure of the Security Council to contain the regional threat posed by Iran and to protect the Iranian people, as well as the limited reach of the responsibility to protect principle. We fear that chronic failure by international norms and institutions to effectively address serious and legitimate security concerns of States that have the capacity to “take the law into their own hands,” is likely to result in the continuing demise of the post World War II norms and institutions.
Self-preservation as an exception to the law
The gap between discussions over the international legality of Operation Epic Fury and actual State reactions suggests another fundamental point regarding the ultimate reach of the international legal system – one that goes beyond the “illegal but legitimate” discourse. Underlying Israel’s military action in both Operation Rising Lion and Roaring Lion (or Epic Fury) is a deep apprehension about the Iranian regime’s strong commitment to (or obsession for) the project of destroying the State of Israel. Such a commitment manifests itself not only in official declarations by the leadership of the Islamic Republic, popular slogans (‘Death to America,” “Death to Israel”) and public spectacles devoted to this eliminationist theme; it also reveals itself in concrete policies consistent with those goals: a nuclear weapons project, a ballistic weapons program, an “axis of resistance” around Israel comprised of proxy armies, and a global campaign of terrorism against Jewish and Israeli targets. It is fair to say that the destruction of Israel – a country which has no border with Iran, and no historical conflict with it – has become a foundational ideological pillar of the Islamic Republic. We know of no other precedent in modern international relations where a State has called out for decades, openly and consistently, for the destruction of another State, and has shown in its activities and resource allocation that it will go to extreme lengths to achieve that goal.
To be sure, such a situation is not without an international law remedy: the Security Council could and should have enforced international law standards on Iran including the prohibition on the threat of use of force and the prohibition of incitement to genocide. The Council could and should have also acted to remove the threat Iran posed to international peace and security; and it could have even recommended to the General Assembly to remove Iran from the UN for violating the foundational principles of the Charter. Yet none of that happened due to the prevailing paralysis and strong anti-Israel sentiment in the UN, and Israel was left to address the growing existential threat posed to it by Iran without being able to effectively trigger the UN collective security mechanisms, and with very limited ability to deal itself with the threat while meeting the strict requirements of jus ad bellum. Indeed, according to almost all international law scholars, Israel has no legal right to defend itself against the Iranian threat before an armed attack against it became imminent or has already begun. Thus, Israel has been required, as a legal matter, to wait for Iran to mortally strike it or for such a mortal attack to become imminent, before it was able to legally respond militarily. Note that, given the extreme religious ideology espoused by the leadership of Iran, even a policy of mutual assured destruction would not have necessarily provided Israel with sufficient reassurances against the possible realization of the threats made against it by the Iranian regime.
Arguably, the paralysis of the Security Council and its inability to deal with threats such as those generated by Iran should have resulted in the emergence of a more flexible and expansive interpretation of what constitutes an armed attack, and a more liberal right to self-defense under Article 51, adapting legal doctrine to geopolitical realities and to extreme threats. But the trajectory of international lawyers and international law institutions seems to have been running mostly in the opposite direction. For example, when Israel embarked on its June 2025 Rising Lion operation against Iran, most responses from international lawyers were very negative (notwithstanding the strong links between Iran and the ongoing acts of aggression by its proxies, and two large-scale rocket attacks launched by Iran against Israel during the 2023-2025 regional conflict). In addition, the judgments and advisory opinions of the International Court of Justice on the use of force that were issued over the years have consistently interpreted the right of States to resort to self- defense in an increasingly restrictive manner. (see e.g., Nicaragua, at para. 195, Wall, at para. 139, Oil Platforms, para. 76-77).
As a result of this continued insistence on a strict and limited interpretation of States’ rights to resort to self-defense measures, some States may now face the following critical conundrum: How to operate within an international law framework to address situations where the failure of international institutions to effectively exercise their authority results in leaving in place an existential threat to them? In the face of this dilemma, some States have resorted, at least implicitly, to the old “right of self-preservation,” which many scholars considered as defunct under the UN charter regime (see e.g., here and here).
To recall, the 19th-century right of self-preservation represented the apex of Westphalian sovereignty, serving as an “absolute” or “inherent” right that preceded—and often superseded—the formal obligations of international law. Rooted in the natural law traditions of scholars like Vattel, the doctrine posited that a State’s primary legal and moral duty was its own survival. Unlike the modern, treaty-based right of self-defense, self-preservation was an elastic concept used to justify a wide array of actions, from preventive military strikes, through forceful interventions in the internal affairs of neighbouring States, to suppressing political instability that might “contaminate” a sovereign’s security. The “conventional wisdom” of international lawyers is that the right to self-preservation was limited by the Caroline principles, and later supplanted by the UN system which did not explicitly recognize this right. Rather the Charter invested responsibility for international peace and security, including the preservation of States, in the Security Council. Yet, one could argue that this natural right kept lurking below the surface, manifesting itself on rare occasions and extreme circumstances – such as those mentioned in the famous (or infamous) paragraph 97 of the Nuclear Weapons advisory opinion, but also in US post-9/11 practice and in the Israeli-Iranian context (as well as arguably in the text of Article 51 itself, which refers to the preservation of State’s “inherent” right of self-defense)
In actuality, geopolitical realities, including military deterrence and the nuclear umbrella, meant the States rarely faced an existential dilemma after 1945. Until 1989, the bipolar world order meant that most States were protected from existential threats because of their association with one of the two great powers. The collapse of the Soviet bloc in 1989, and the parallel rise in the power of international institutions in the post-Cold War era, seemed to suggest that international organizations would now be able to confront existential challenges to States, such as the 1990 Iraqi invasion of Kuwait.
A destabilizing change in geopolitical conditions in the early 21st century meant, however, that States had to revise their calculations. In the 21st century, too many States (both from the Global North and South) ignore or manipulate international law norms and institutions with impunity, and the liberal international order appears less and less capable of meeting the expectations developed after the end of the Cold War. In particular, the RBIO seems no longer able to protect through international institutions the self-preservation interest of many States. The full invasion of Ukraine by Russia in 2022, which put the former under an existential threat, is a case in point for the relative weakness of the Security Council (although the international law of self-defense clearly covered the situation and facilitated international assistance to Ukraine).
This change in the international society is roughly analogous to domestic changes fueling some of the current political crises in liberal democracies. In many Western democracies, the perceived decline in the ability of government to confront serious domestic challenges allowed for populist forces to rise in a manner that threatens the dominant political and legal institutions and conventions in these countries. A similar change appears to be happening now in international law: When the liberal world order is perceived to have failed in ensuring critically important interests of States, States increasingly adopt positions which challenge or ignore the RBIO. Part of this challenge might involve the resuscitation of claims for a “right to self-preservation” as a form of self-help or collective self-help, at least in extreme cases involving real existential threats like those underlying Operation Epic Fury/Roaring Lion.
Still, such developments are highly problematic in our eyes, given the obvious potential for abuse by any given State invoking the right to self-preservation. Hence, the better course for the international law community to pursue is to make every effort to effectively handle threats to international peace and security before they become existential threats, which push threatened States to resort to extreme measures outside the existing international law framework.
Concluding remarks
The joint move toward a return to “illegal but legitimate” justification and the possible reemergence of the “right of self-preservation” around Operation Epic Fury presents a grave challenge to the RBIO. This challenge, however, does not mean that the international legal order has been irreparably broken. First, the tensions we have identified are particularly acute when a State faces an existential threat and, as in here, from an enemy long committed to radically unlawful behavior. Second, Israel and the United States did not ignore international law, but rather tried to justify their actions through the traditional language of international law in order to generate political and military support for their cause. Similarly, when the United States created the Board of Peace for Gaza, it was able to obtain a Security Council resolution, providing it with some formal international law basis. We suggest that these efforts to locate controversial State action within the framework of the international order should not be considered as mere political or rhetorical manipulations. Rather, these statements and efforts suggest that even States challenging the current order might be looking to revise it in ways which would reflect their critical security interests, and not to ditch it altogether.
Ultimately, we believe Secretary Rubio’s criticism of the UN’s ineffectiveness in resolving problems and the use of international law as a shield for abusers does underscore a real policy problem. Like their domestic counterparts, international law norms and institutions are designed to create conditions for dealing with real life problems in a manner that is just and effective. Once international lawyers and institutions stop engaging seriously and professionally in problem-solving and turn to political grandstanding or lecturing States on how to behave without offering them credible practical solutions to their actual and acute problems, they bring the whole field into disrepute and, ultimately, irrelevance. It would be desirable If the current (existential) crisis of the RBIO leads to some introspection in the international legal community and to calls for a feasible and pragmatic reevaluation of international law norms and institutions.
