The Iran–Israel War and the Ethics of Pre-emption

In the early hours of 13 June 2025, Israel launched Operation Rising Lion, a large-scale strike on Iranian territory. Over 200 fighter jets delivered more than 300 precision-guided munitions to approximately 100 targets, including nuclear enrichment sites at Natanz and Fordo, as well as facilities affiliated with Iran’s Revolutionary Guard Corps, research labs, and senior military residences. Israeli officials justified the strike as an act of “pre-emptive”, anticipatory self-defence, citing credible intelligence that Iran was only weeks away from developing nuclear weapons. In response, Iran initiated Operation True Promise III, unleashing coordinated missiles and drones on Israeli cities, resulting in significant civilian casualties on both sides. By 30 June, Iran’s HRANA reported 974 deaths and over 3,400 injuries. Among the dead were 387 civilians, 268 military personnel, and 319 unidentified individuals. Israel reported 28 civilian deaths and over 3,000 injured from Iran’s retaliatory strikes.

The immediate political and military implications are grave. News focus has leaned toward military outcomes, oil prices, and US involvement. Yet beyond strategic analysis lies a more urgent philosophical question: can the deliberate use of force, in the absence of an actual armed attack, ever be morally justified? And what precedent does this strike set for the international community? I argue that accepting Israel’s rationale risks legalising a doctrine of first-strike coercion globally.

Pre-emptive vs. Preventive War: A Moral Distinction

Just war theory, stretching from classical sources such as Augustine and Aquinas to contemporary figures like Michael Walzer and Jeff McMahan, has traditionally distinguished between pre-emptive and preventive war. The former refers to the use of force in response to a threat that is imminent and unavoidable; the latter to a speculative strike against a state that may, at some undefined future time, pose a danger. Only genuine pre-emption can be morally justified. It must satisfy three stringent conditions: imminence, meaning the threat is instant and overwhelming; necessity, meaning no peaceful alternatives remain; and proportionality, meaning the harm inflicted must not exceed what is required to repel the threat.

In his influential book Just and Unjust Wars, Michael Walzer—drawing on the Caroline precedent—argues that states may act in self-defence only when the threat they face is “instant, overwhelming, and leaving no choice of means, and no moment for deliberation” (Walzer, 2006, p. 74). Jeff McMahan goes further, arguing that even when threats are imminent, those targeted must be morally liable for the harm inflicted (McMahan, 2009). Killing non-combatants, or those not directly responsible for the threat, fails to meet this test, rendering the use of force morally unjustifiable.

Israel’s justification hinges on the concept of imminence, claiming that Iran was “weeks, not months” away from acquiring a nuclear capability. Yet, the International Atomic Energy Agency’s (IAEA) May 2025 report stated that Iran had enriched uranium to 60%—well below the 90% weapons-grade threshold—and found no evidence of a nuclear warhead or delivery system. While the IAEA assessed that Iran possessed enough fissile material for several weapons if further enriched, nuclear experts widely agree that Iran has not taken steps toward weaponisation. Developing a deliverable nuclear weapon involves complex engineering beyond enrichment alone and would likely require several additional months or even years. These assessments fall short of the “instant” and “overwhelming” threat required by the Caroline standard—long regarded as the moral and legal benchmark for legitimate pre-emption.

Just war theory also requires that force be a last resort. Prior to the attack, diplomatic efforts—mediated by Oman and supported by EU and US officials—were reportedly underway and due to resume on 15 June. Israel’s decision to strike days earlier undercuts the claim that peaceful avenues were exhausted. Moreover, past Israeli sabotage efforts (including the Stuxnet cyberattack and assassinations of nuclear scientists) had significantly delayed Iranian enrichment without triggering full-scale war. The availability of such alternatives casts further doubt on the necessity of the Rising Lion operation.

As for proportionality, the potential consequences of attacking active nuclear sites are not confined to military infrastructure. Independent expert assessments, echoing worries raised during the Zaporizhzhia crisis, warned that a strike on Natanz risked releasing radioactive particles into the groundwater and surrounding atmosphere, with long-term consequences for Iranian civilians and regional ecosystems. Even assuming Israel’s strikes were narrowly targeted and technically successful, they establish a norm that may be seized upon by less discriminating states, legitimising large-scale destruction under the thin veil of pre-emption.

Does Israel meet the just-war criteria? Judged against the standards of imminence, necessity, and proportionality, Israel’s strike appears to fall short on at least two grounds—and arguably all three—suggesting not a case of legitimate pre-emption, but one of preventive aggression cloaked in the language of self-defence. Preventive war is morally unjustifiable under just war theory because, at its core, just war reasoning insists that the use of lethal force requires a present moral necessity. Preventive war, by contrast, is a gamble on the future—it punishes not actions, but possibilities. It claims moral legitimacy not from what is, but from what might be. That logic erodes the entire structure of moral restraint that just war theory is designed to uphold. If suspicion alone justifies war, we open the door to endless cycles of anticipatory violence, where fear becomes its own warrant. In such a world, no nation is safe, and no peace is secure. Just war theory draws the line here for a reason: to insist that force must respond to wrongs that are real and unfolding—not those merely imagined.

Legal Justifications and Their Limits

International law is similarly constrained. Article 2(4) of the United Nations Charter prohibits the threat or use of force against the territorial integrity or political independence of any state. The only exception, found in Article 51, is the “inherent right of individual or collective self-defence if an armed attack occurs”. Israel’s strike, however, occurred prior to any attack by Iran. While some states and scholars have argued for an expanded interpretation of self-defence under customary international law, this view remains contested. Israel’s lawyers invoke customary allowances for anticipatory self-defence, yet neither the International Court of Justice nor the General Assembly has ever endorsed such an elastic reading. The International Court of Justice, in the Nicaragua case (1986), rejected the idea that self-defence could be lawfully exercised against a merely anticipated attack. Normalising it now would empty Article 51 of meaning and re-legitimise the 19th-century norm of “might makes right”.  

That concern was stressed by UN experts, who condemned Israel’s strike as a “blatant act of aggression” and a “flagrant violation” of international law. In their view, claims of preventive self-defence against nuclear proliferation violate jus cogens norms—peremptory rules from which no derogation is allowed. The experts cited over 200 deaths in Iran, mostly civilian, and warned that normalising such force risks collapsing the international legal order and undermining global peace initiatives.

If the threshold for anticipatory self-defence continues to erode, what remains of the UN Charter’s prohibition on force? The danger is not just legal ambiguity—it is moral hazard. Once a powerful state succeeds in rebranding a speculative strike as legitimate self-defence, others will surely follow.

Can Existential Threats Justify Pre-emption?

A common defence of Israel’s June strike appeals to the existential nature of the threat. Iran has repeatedly called for the end of the Israeli state, and its support for groups like Hezbollah and Hamas—both committed to Israel’s destruction—seems to add weight to that rhetoric. Recently, former German Chancellor Angela Merkel echoed this concern, stating: “If the existence of a country is called into question by Hamas or Iran, that is not so easy to answer on the basis of international law”.

This objection carries undeniable historical and emotional force. For a state created in the aftermath of genocide and through legally contested and often violent processes of territorial expansion—most notably in the occupied Palestinian territories—existential threats carry profound psychological and political weight and cannot be taken lightly. But fear—even justified fear—cannot alone determine the moral or legal permissibility of pre-emptive killing.  

Philosophically, there is a crucial distinction between rhetorical hostility, indirect support, and operational imminence. However hostile Iran’s ideological stance may be—and however real its material support for groups like Hezbollah and Hamas—these factors alone do not meet the threshold for pre-emptive war under just war theory. Anticipatory self-defence requires that a threat be not only grave, but also specific, immediate, and unavoidable. Support for proxy groups may constitute a long-term security concern, but it does not in itself amount to an armed attack by the state, nor does it establish that an attack by the state is imminent. If the existence of enmity, or even indirect involvement in violence, were enough to justify pre-emptive war, then no state would ever be safe from being targeted on suspicion alone. This is precisely the slippery slope that just war theory seeks to avoid.

Crucially, just war reasoning insists on moral discrimination: those who are not directly responsible for a threat must not be treated as if they are. Even if Iran provides material support to armed groups, this does not make every Iranian facility, scientist, or civilian a legitimate target. Collective punishment is morally untenable. Pre-emption that targets an entire state for the actions of affiliated groups blurs the line between defence and retribution. Even if Iran’s conduct is destabilising, the moral and legal bar for anticipatory force must remain high. Otherwise, we risk legitimising a model of security grounded not in restraint, but in escalation.

Why This Moment Matters

This conflict matters not only because of its immediate victims but because of the precedent it sets. If Israel’s rationale for anticipatory self-defence is accepted, then any state with drones and a threat narrative—China, Russia, Pakistan—might adopt a similar approach. If "likely enrichment" counts as an imminent assault, Pakistan could pre-empt India, North Korea could cite US bombers on Guam, and China might label routine patrols near Taiwan a casus belli. The architecture of global security, already under strain, risks collapsing into a world where fear justifies force and suspicion replaces evidence.

Moreover, emerging technologies and tactics are drastically compressing the decision-making timeline between threat detection and response, increasing the likelihood of first-strike logic. Hypersonic missiles reduce reaction windows to minutes; AI-powered drones may be deployed without real-time human oversight. As the time between threat detection and military response shrinks, the pressure to act and strike first grows. Such systems do more than accelerate response times; they erode the very distinction between wartime and peacetime. Moral reasoning, already strained in traditional warfare, becomes even more urgent—and more easily bypassed. The Charter works because most states believe most others will obey it most of the time. Highly publicised breaches erode that faith, nudging rivals toward arms races and “first-move” doctrines—embracing asymmetric escalation and doctrines of “relative superiority”, where speed and surprise outweigh legality and proportionality.

What Can Be Done?

Governments must reassert the narrow interpretation of Article 51 and resist the temptation to retroactively justify morally dubious strikes with legal justifications. The international community should insist that claims of imminent threat be independently verified—through multilateral mechanisms, wherever possible, such as the IAEA or UN-mandated inquiries, or through bilateral arrangements that include neutral third-party observers—rather than relying solely on classified intelligence from the state contemplating the use of force.

Civil society also has a role to play. They can demand transparency, pressing parliaments and media for FOIA coverage of threat assessments before any strike. Scholars, journalists, and activists must insist on transparency, scrutinise threat claims, and expose moral shortcuts. Universities and policy institutes should promote just war reasoning and train the next generation of leaders to ask not just can we act, but should we?

The current moment is not only a crisis in the Middle East—it is a test of whether the world still believes that war should remain an exception to peace, not its strategic extension. Beyond questions of military efficacy—was Natanz dented?—we must confront the fundamental question: should anticipatory force ever override established moral and legal norms? Just war reasoning offers three citizen-accessible tests. First, is the threat genuinely imminent? The answer must rest on independently verifiable evidence, not classified assertions alone. Second, are peaceful alternatives truly exhausted? Transparency around ongoing diplomacy is essential. Third, are civilian harms proportionate to the military objective? Official projections should err on the side of caution, not strategic optimism. Israel’s strike fails at least two, undermining moral legitimacy. That verdict does not deny Israel’s right to defend itself—it insists that even just defence must obey moral boundaries essential for global security.

Conclusion

Pre-emptive war is not necessarily unjustified. In some cases—where threats are truly imminent, alternatives are exhausted, and lives are immediately at stake—it may be the only moral option. But the Israel–Iran conflict does not meet those conditions. Rather, it marks a dangerous blurring of moral and legal lines, a move that, if accepted, invites all nations to normalise force as policy rather than last resort. When that happens, the first casualty is not merely peace—but the principle that human lives must never be taken lightly, even in the name of security.

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About the Author

Hossein Dabbagh is an assistant professor of philosophy at Northeastern University London and an affiliated member of the Oxford Department for Continuing Education. His published research stretches across three broad fields: moral philosophy, political theology, and practical ethics.