Nothing under international law may justify these armed attacks and the deliberate targeting of protected civilians.
Saïd Benarbia, ICJ Middle East and North Africa Programme Director
I do not agree that the terms or intent of Article 51 eliminate the right of self-defence under customary international law…
Judge Schwebel, dissenting, ICJ Nicaragua case (1986)
Prolegomena
Israel’s June 2025 unilateral attack on Iran’s nuclear program tests the boundaries of self-defence in a world the UN Charter wasn’t built to govern. For decades, Israeli policy has emphasized that it will not allow Iran to acquire nuclear weapons. The strikes fulfilled that doctrine. It followed years of diplomacy, sabotage, and shadow war. And it came after repeated warnings that Iran had crossed enrichment thresholds and could reach nuclear breakout within months. That moment, Israeli Prime Minister Benjamin Netanyahu argued, demanded immediate action.
Under Article 2(4) of the UN Charter, states are prohibited from using force against the territorial integrity or political independence of any other state. The only explicit exception is found in Article 51: the “inherent right of individual or collective self-defence if an armed attack occurs.”
Israel has not claimed that Iran launched a missile or invaded its territory. Instead, it argues that a nuclear Iran would present an irreversible threat—one that could not be deterred, reversed, or neutralized once operational.
This raises a foundational question: What kind of threat justifies the use of force in self-defence before an actual armed attack? Or more sharply: Can international law afford to wait for the flash of a nuclear detonation before permitting a state to act?
Israel’s June 2025 strike on Iran’s nuclear facilities is more than a military maneuver – it’s a collision between 20th-century legal doctrine and 21st-century existential risk. In a region shaped by proxy wars, nuclear aspirations, and enduring enmity, the attack did not occur in a vacuum. It was the culmination of years of strategic signaling, red lines, and international paralysis. And it forces us to confront whether international law – as currently written and applied – can meaningfully contend with irreversible threats like nuclear breakout.
The Strike Before the Storm: Israel, Iran, and the Specter of Imminence
In the early hours of June 13, 2025, Israel launched a devastating and meticulously coordinated strike against more than a dozen military and nuclear targets deep inside Iran. These included the Natanz enrichment facility and high-value assassinations of senior nuclear scientists and Quds Force commanders. The timing was conspicuous: the sixth round of US–Iran nuclear negotiations was just days from resuming. While no breakthrough was imminent, diplomacy – however fragile – was still on the table.
These negotiations had been ongoing for 60 days, the artificial deadline set by US President Donald Trump for a final agreement. Progress had been minimal, but the talks were continuing. There were whispers of a possible compromise: allowing Iran to retain 5–10% enriched uranium for civilian use – well below weapons-grade, but still anathema to Netanyahu. For Netanyahu, any level of enrichment by the Islamic Republic, regardless of purpose, is intolerable.
The timing raised eyebrows not just for its proximity to the talks but because it intersected with another diplomatic front: France and Saudi Arabia were preparing to co-host a high-profile summit aimed at reviving the moribund Israeli-Palestinian peace process. That initiative – stillborn many times over – poses a political threat Netanyahu has spent years working to deflect or sabotage. A viable two-state solution is politically radioactive for his hardline coalition, whose de facto policy has been one of slow annexation and demographic erasure, particularly in the West Bank – and now Gaza.
The war in Gaza is formally unrelated to the strike in Iran. Yet it is precisely the conduct of that war – its staggering civilian toll, the systematic destruction of infrastructure, the weaponization of humanitarian aid, and credible allegations of war crimes – that has eroded global moral support for Israel’s existential security concerns. With senior Israeli officials and retired military officers openly acknowledging that war crimes and crimes against humanity are likely occurring, and with widespread belief that the war is being prolonged to shield Netanyahu from domestic prosecution, the international narrative is rapidly collapsing into a binary: Israel is acting out of impunity, not necessity.
And yet, necessity does exist. Netanyahu invoked the imminence of an Iranian nuclear capability – specifically, the accelerated development of both warheads and ballistic delivery systems – as justification for the June 13 operation. The threat is real. Iran’s ambitions are well known. Israeli intelligence reportedly believes Iran is mere months away from full nuclear breakout, with missile delivery systems already operational. While hard evidence wasn’t shared publicly, former Prime Minister and Defence Minister Ehud Barak, a figure of unimpeachable security credentials, confirmed the seriousness of the threat in a recent CNN interview with Christiane Amanpour. So, I for one, accept the exigencies of the moment.
But a capability that is “months or a year away” is not, by classical legal standards, imminent. The strike’s timing – on the eve of resumed negotiations – renders it suspect. Netanyahu could have waited days. Perhaps even weeks. The logic of preemption falters when the clock still has time.
Still, legality is not always reducible to timing. A strike may be premature by diplomatic standards and yet legally justified if the threat, once realized, would be irreversible and existential. A nuclear strike would meet that threshold. It cannot be that Israel must wait to absorb such a blow before it can act to prevent it. That’s suicidal.
But why strike now?
To understand the logic, one must look past the calendar and into the Israeli calculus. For Prime Minister Benjamin Netanyahu, any Iranian enrichment – civilian or military – is an existential threat. The nuclear clock was ticking, and diplomacy, in Israel’s eyes, had failed. To Netanyahu, these were not reasons to wait – they were windows that could soon close.
The Foggy Line Between Preemptive and Preventive
International law, at least as codified in Article 51 of the UN Charter, is strict: self-defence is permitted only “if an armed attack occurs.” But customary international law has long been more flexible, allowing anticipatory self-defence under narrow circumstances: when a threat is imminent, overwhelming, and leaves “no choice of means and no moment for deliberation” (Caroline standard, 1837). By those lights, Israel’s June 13 strike sits in a legal grey zone.
Was the threat imminent? Not quite. Israeli intelligence reportedly warned that Iran was just months from a nuclear breakout. That’s urgent; not immediate. The International Atomic Energy Agency (IAEA) had recently lost access to inspection sites, Iran’s enrichment was accelerating past 60%, and missile development was advancing. Still, there was no missile in the sky, no warhead on a truck, no detonation test. The threat was real – but not yet realized.
Under a strict interpretation of the law, that would render the strike unlawful. But Israel’s legal defence likely rests on two pillars: necessity and proportionality. First, that the strike was necessary because once nuclear capability is achieved, it is irreversible. And second, that the action was proportionate to the scale of the threat—a potential nuclear annihilation of a state the size of New Jersey.
Perhaps Israel is stretching the doctrine of anticipatory self-defence. I think not. But in any event, what’s the alternative?
In today’s strategic environment—where nuclear weapons can be launched in minutes, enrichment can proceed underground, and deterrence is undermined by asymmetric warfare—clinging to a 19th-century standard of imminence is not just anachronistic; it is dangerous.
Anticipatory self-defence in this context must account not only for timing, but for irreversibility. Once a nuclear capability is operationalized, neutralizing it becomes exponentially harder and riskier. The Israeli strikes may be understood, then, not as aggression, but as a last-resort effort to delay or degrade a maturing existential threat.
Still, the legal footing remains unstable. Precedent is scarce, and global consensus deeply fractured. The International Court of Justice has repeatedly reaffirmed the Charter’s prohibition on the use of force, rejected preemptive self-defence as a general principle, and emphasized the primacy of peaceful resolution and state accountability. Critics of Israel’s strike rely on these positions to cast it as unlawful and dangerously destabilizing. The flip side to this criticism is whether Israel had much of choice. The timing might be open for debate but not the inevitability that sooner or later, it might be too late for Israel to act.
But the deeper question remains: what doctrine can credibly guide state behavior when threats evolve faster than diplomacy can contain them? The challenge for international law is not to prevent states from defending themselves—it is to remain relevant when survival is on the line.
The International Commission of Jurists (ICJ), however, was unequivocal:
The ICJ condemns Israel’s use of armed force against Iran’s sovereignty and territorial integrity as a grave violation of the United Nations Charter and international law and a major threat to international peace and security.
Recalling IAEA warnings that attacks on nuclear facilities risk catastrophic radiation and long-term environmental harm, the ICJ noted the broader implications: Iran responded by announcing a new enrichment facility – its first major escalation since the IAEA Board of Governors found it in violation of non-proliferation obligations.
The ICJ’s Middle East and North Africa Programme Director, Saïd Benarbia, issued a passionate appeal:
The UN Security Council must live up to its responsibilities in preventing and ensuring accountability for grave violations of the UN Charter and related threats to international peace and security. Watching idly by…is not an option.
It’s not hyperbole, it’s reality: the Security Council has long been paralyzed by permanent-member vetoes wielded less in the interest of peace than in defence of national allies or geopolitical agendas. The UN is not an arbiter of justice. It is a theater of power. And Israel knows this. So does Iran. No one should mistake the UN as a global institution of a legal system with enforceable norms. It is a political body that claims to promote order with rules that are bent—or ignored—by the strong. The UN can pass resolutions, but it cannot compel compliance. And certainly not from nuclear-armed or strategically indispensable states.
This is what makes the strike so troubling. Not because Israel acted irrationally – it didn’t. But because the international legal system, already on life support, was not equipped to respond to a world where nuclear threats are real, diplomacy is fraying, and enforcement is a mirage. Israel struck because it believed no one else would stop Iran. And the world’s broken machinery offered no credible deterrent.
Parsing Self-Defence: Legal Labels and Practical Realities
When examining the legal definitions, the factual context of the strikes, and how international law frames the right of self-defence under both the UN Charter and customary international law, one quickly sees that – apart from labeling the strikes as unprovoked (which they clearly were not, circumstances considering as explained) – the distinctions between different types of self-defence often become academic. The differences are discernibly obtuse, bordering on the logical fallacy of making distinctions without a difference. To navigate this debate, legal scholars often distinguish among anticipatory, preemptive, and preventive self-defence:
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- Anticipatory self-defence responds to an imminent armed attack (e.g., mobilized troops at the border).
- Preemptive self-defence responds to a serious but not immediate threat (e.g., enemy military build-up).
- Preventive war targets long-term threats that may emerge in the future (e.g., destroying a rising power’s capabilities).
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The line between these categories is blurry. In the nuclear context, it may be meaningless. A regime months or a year from breakout cannot be treated like one poised to sign the Non-Proliferation Treaty (NPT). Once Iran crosses the enrichment threshold and weaponizes its program, the strategic—and psychological – balance of power in the region would change forever.
Israel’s June 13 strike arguably straddles the line between anticipatory and preemptive self-defence. It was certainly not preventive in the speculative sense, and it was decidedly not unprovoked. The operation followed decades of threats, proxy conflicts, and explicit hostility from Iran’s leadership—including calls for Israel’s destruction and persistent nuclear ambitions.
Anticipatory self-defence targets an imminent attack; preemptive action strikes before imminence fully crystallizes. Preventive war, by contrast, seeks to neutralize hypothetical future threats. Israel’s strike doesn’t fit neatly into any of these boxes, but it sits closest to the anticipatory model – albeit at its outer edge.
Under the Caroline test and Article 51 of the UN Charter, self-defence turns not on the gravity of a threat, but its immediacy. Imminence is the threshold. Israel wasn’t responding to an incoming missile barrage, but also wasn’t acting on a speculative hunch either. It made a judgment: that Iran’s nuclear program had crossed a threshold where delay would be fatal. In this light, the strike appears legally contentious, politically calculated, and strategically designed to fall just inside the anticipatory frame.
The International Court of Justice has tried to cabin anticipatory self-defence tightly – most notably in Nicaragua and subsequent advisory opinions. Indeed, it and much of the legal academy remain hostile to anything that resembles preemptive or preventive war. But history is less doctrinaire, and state practice has long diverged from the theory. The U.S. invoked anticipatory self-defence in 2003 to justify the invasion of Iraq – albeit on false premises. Israel invoked it in 1981 when it bombed Iraq’s Osirak nuclear reactor. The 2007 Israeli strike on Syria’s Al-Kibar reactor received far less criticism, precisely because the risks of inaction were so clear. Neither operation received UN Security Council authorization. Both were condemned at the time. And yet, both were later, if not celebrated, quietly vindicated.
This pattern should give us pause. It doesn’t necessarily mean the law is broken. But it does suggest that the doctrine of self-defence is struggling to keep pace with the kinds of threats that define the 21st century. When a nuclear capability is built in shadows and unfolds over years – not hours – the legal framework must either adapt or risk obsolescence. The challenge isn’t to abandon legal constraints, but to reconcile them with the strategic realities they were meant to govern.
Existential Stakes and Strategic Calculus
What sets the 2025 Iran strike apart is not the legal classification of the act, but the irreversibility of the threat it was designed to forestall.
Iran has spent years violating its obligations under the NPT, curtailing IAEA inspections, enriching uranium to near-weapons-grade levels, and developing delivery systems capable of reaching Tel Aviv. Tehran’s support for Hezbollah, Hamas, and regional militias adds another layer: the possibility of nuclear technology or materials leaking into the hands of non-state actors. Iran claims its nuclear program is peaceful. But that claim, long shadowed by concealment, stonewalling, and regional aggression, no longer earns global deference.
Justice Robert Jackson once warned at Nuremberg that the law must not become “a pretense for unpunished aggression.” But nor can it become a straitjacket that prevents states from acting to ensure their survival. The key question, then, is whether the doctrine of self-defence must adapt to nuclear realities. A nuclear Iran cannot be “uninvented.” The threat is not only grave – it is permanent.
For Israel, the stakes are not hypothetical. A single nuclear warhead detonated over Tel Aviv would be the end of the state. That’s not alarmism – that’s physics. Iran is not some helpless, neutral actor misunderstood by the West. It remains the world’s leading state sponsor of terrorism, has vowed to eliminate Israel, and continues to enrich uranium in violation of past agreements. Its actions – arming and funding Hezbollah, Islamic Jihad, the Houthis, and others – make clear that its rhetoric is not symbolic but operational. It coordinates, trains, and supports actors explicitly dedicated to Israel’s destruction.
And it does so with maniacal consistency. Despite crushing sanctions, international isolation, and covert sabotage efforts, Iran has doubled down on nuclear development and missile delivery capabilities. It is difficult to look at this decades-long pattern and seriously claim that Iran would refrain from using nuclear weapons if given the chance – especially against a country it calls a “cancerous tumor” that must be wiped off the map.
Whether those intentions would materialize into an actual nuclear strike is unknown. Some international lawyers, including the ICL (not to be confused with the International court of Justice, have labeled Israel’s strike “aggression.” Others decry it as illegal under Article 2(4) of the UN Charter. While these views reflect an understandable desire to preserve the international legal order, they fail to reckon with the asymmetry of consequences. For Iran, violating legal norms brings censure and sanctions. For Israel, inaction could mean annihilation. You don’t need to be a geopolitical genius or a nuclear physicist to appreciate that if the Ayatollahs get the bomb, they will use it— one way or another. That calculus – chilling but not irrational – explains why Israel cannot wait for legal clarity or for UN Security Council authorization.
A legal regime that treats a nuclear-armed Iran as a theoretical threat—and prohibits force until missiles are in the air—is not just outdated. It is dangerous. So even as we acknowledge that Israel’s actions stretch the current bounds of international law, we must also ask: Is the law sufficient for an age in which the price of delay is annihilation?
From Israel’s perspective, the gamble is too great. Unlike superpowers, Israel cannot afford to absorb a first strike. Its doctrine of preemption – born out of the 1967 Six-Day War and hardened by decades of asymmetric warfare – is not just military policy; it is national survival strategy.
Critics argue that the strike undermined ongoing diplomacy. Perhaps. But Netanyahu likely viewed that diplomacy as kabuki theater: a delaying tactic while Iran edged closer to the point of no return. In that context, striking before a deal tied Israel’s hands may have seemed not only rational – but urgent.
The bottom line is that Iran has spent decades cultivating proxy militias, threatening Israel’s existence, and refining dual-use nuclear capabilities. The legal system, admirable in theory, often proves impotent when faced with regimes that are both determined and indifferent to legal constraint. Iran has exploited these limitations for years. Rhetorically and materially, it has made clear its intentions. And those intentions pose an existential not a theoretical threat to Israel.
[Part II forthcoming: Sovereignty, Paralysis, and the Future of International Law]
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