Israel and America’s Legal Case for Self-Defense |
The Law of Self-Defense and the Iran Conflict In moments of crisis, the international legal debate often begins with a simple question: who started the war? But that question can obscure a more important one: is the use of force part of an ongoing armed conflict or an initiation of hostilities? The distinction matters enormously under international law. When a state is already subject to armed attack, the law of self-defense does not require it to absorb repeated blows before responding.
Both Israel and the United States now argue that their military actions against Iran fall squarely within that framework.
Israel’s Case: Continuing Self-Defense in an Ongoing Conflict Israel’s current strikes against Iran can be framed not as the initiation of a new war, but as a lawful operation within an ongoing international armed conflict between two states.
Under Article 51 of the United Nations Charter, a state has the inherent right of self-defense if it has been subjected to an armed attack.
Iran directly launched a large-scale missile and drone attack against Israel in April 2024. That event alone qualifies as an armed attack under the Charter framework.
Once an armed attack occurs, the victim state’s right of self-defense does not expire after the first exchange of fire; it continues until the threat is neutralized and the armed attack campaign is effectively terminated.
In addition to direct Iranian strikes, Israel has for years faced sustained armed attacks from Iranian-backed proxy groups such as Hezbollah, Islamic Jihad, and Hamas.
These attacks long predate October 7, 2023 and form part of a broader regional conflict architecture in which Iran has armed, funded, trained, and operationally supported forces positioned on Israel’s borders.
Is it indisputable fact that Hamas did launch a war on Israel, and the Iranian regime supported that war directly by unleashing its others proxy forces in Lebanon, Iraq, and Yemen to attack Israel, in addition to attacking Israel itself directly.
This proxy architecture is not accidental; it is central to how Iran wages conflict.
A core feature of the strategy is to operate through militias and partner forces, disperse them among civilian populations, and blur attribution to complicate deterrence and create legal ambiguity.
By sustaining attacks through proxies, conducting operations below the traditional threshold of conventional war, and then shifting responsibility away from the Iranian state, Iran seeks to turn the law’s gray areas into operational cover.
But the underlying reality remains that proxy warfare can still constitute armed attacks for Article 51 purposes, and the use of intermediaries does not immunize a state from responsibility when it arms, trains, funds, and operationally enables the violence.
Under widely recognized principles of state responsibility, a state that organizes, equips, finances, or operationally supports armed groups carrying out attacks may bear legal responsibility for those attacks even if it does not exercise day-to-day command over every operation.
While some may debate whether the Iranian regime has sufficient control or direction over Hamas, it is clear that the regime has near total control over Islamic Jihad and Hezbollah, qualifying these proxy operations as armed attacks attributable to the Iranian state itself. All are part of the regimes “Axis of Resistance” organized and funded by the Iranian Revolutionary Guard Corps (IRGC).
Even apart from formal attribution debates, the sustained pattern of coordinated hostilities supports the characterization of an ongoing armed conflict between Israel and Iran. Within that context, Israel’s present operations can be justified as continuing acts of self-defense aimed at degrading Iran’s military capacity to conduct further armed attacks.
International law also recognizes what is often called an “accumulation of events” doctrine, under which a series of coordinated attacks may collectively meet the armed-attack threshold even if no single strike alone would qualify.
International law does not require a state already under attack to wait until its adversary has fully rearmed, consolidated, or improved its strike capability before acting. The requirement under jus ad bellum, or the right to wage war, is necessity and proportionality.
If Israel assesses that Iranian missile infrastructure, command nodes, and military assets are being rebuilt or positioned in a way that creates a renewed or ongoing threat, the use of force to neutralize those capabilities would be considered necessary to prevent recurrence of armed attack.
The fact that Iran has publicly articulated hostile intent toward Israel, while not legally sufficient on its own, strengthens the credibility of the threat when paired with demonstrated attack capability and prior use of force.
Iran’s advancing missile and nuclear-related capabilities further shape the necessity analysis.
While nuclear enrichment alone does not constitute an armed attack, the combination of demonstrated direct strikes, proxy warfare, expanding missile arsenals, and explicit threats contributes to a cumulative threat environment. In such circumstances, Israel could argue that waiting until Iran achieves enhanced strike readiness would materially increase the risk and reduce defensive options. The law of self-defense does not obligate a state to absorb a second or third large-scale attack before acting to dismantle the infrastructure enabling it.
Even if Israel initiated this specific round of hostilities, that fact does not automatically negate its right of self-defense if the broader armed conflict is ongoing.
In an existing international armed conflict, states are not confined to purely reactive fire; they may conduct operations designed to achieve legitimate military objectives consistent with defensive aims. The critical legal test is whether the objective is to neutralize military threats rather than to punish, retaliate for its own sake, or pursue regime change unrelated to the ongoing war.
Under International Humanitarian Law, Israel’s operations must also comply with distinction, proportionality, and precautions in attack. If, as is happening, Israel is targeting Iranian military installations, missile infrastructure, Revolutionary Guard assets, and regime-linked military command structures rather than civilians or purely civilian objects, those targets qualify as military objectives under the law of armed conflict.
Provided Israel conducts proportionality assessments, takes feasible precautions to minimize incidental civilian harm, and refrains from indiscriminate attacks, the conduct of hostilities would be consistent with IHL obligations even if civilian harm occurs unintentionally.
America’s Case: Collective Self-Defense and the Defense of U.S. Forces One of the clearest and strongest legal basis the United States can assert for the use of force against Iran is collective self-defense on behalf of Israel under Article 51 of the U.N. Charter.
Article 51 preserves the inherent right of self-defense if an armed attack occurs against a U.N. Member State. Israel has been directly attacked by Iran, including large-scale missile and drone strikes in April 2024 targeting Israeli territory.
As mentioned, in addition, Iran supports, arms, funds, and directs proxy actors such as Hezbollah and Hamas, which have carried out sustained attacks against Israel over many years, including well before October 7, 2023. Taken together, these actions form part of an ongoing conflict between Israel and Iran.
Under customary international law and long-standing U.N. practice, when a state is lawfully exercising self-defense against an armed attack, it may request assistance from another state.
The assisting state may then lawfully act in collective self-defense, provided its actions are necessary and proportionate to help repel or halt the ongoing attacks.
This rationale does not require the United States itself to have been moments away from being struck at the precise time it acted. Rather, it rests on the fact that the United States is aiding a state that is under continuous and ongoing armed attack. In this framing, American involvement is not an independent war of aggression, but participation in a lawful defensive effort initiated by an ally already engaged in self-defense.
Beyond collective defense, the United States can argue that it has its own independent right of self-defense.
For decades, Iran has directly and indirectly posed serious threats to U.S. forces, personnel, and regional partners. Iranian-backed armed groups have killed and injured thousands of U.S. servicemembers in Lebanon, Jordan, Iraq and Syria.
As examples, in 1983, a Hezbollah suicide bomber attacked the U.S. Marine barracks in Beirut, killing 241 American servicemembers, one of the deadliest single-day attacks on the U.S. military since World War II.
During the Iraq War, Iranian-backed militias conducted countless attacks on U.S. troops. U.S. military assessments repeatedly attributed a significant portion of lethal attacks—especially explosively formed penetrators (EFPs) incidents—to Iranian supply networks and training.
Iran-backed groups such as Kata’ib Hezbollah have repeatedly targeted U.S. forces and facilities in Iraq with rockets, mortars, and drones, underscoring that Iran’s campaign against American personnel has continued well beyond the formal end of major combat operations.
Most recently, Iran-backed militias escalated attacks on U.S. forces across Iraq, Jordan, and Syria with rockets, one-way drones, and indirect fire, all part of a sustained pressure campaign that repeatedly placed U.S. servicemembers under threat. In January 2024, a drone launched by an Iranian-backed militia struck a U.S. base in Jordan, killing three American soldiers and injuring more than forty others.
Iranian missile and drone attacks have now targeted U.S. positions and partner forces as the conflict has expanded, with Iranian retaliatory attacks targeting U.S. bases in Gulf states.
Under Article 51, the right of self-defense is triggered by an armed attack or by an imminent armed attack and from this perspective, U.S. action is legal.
But a key point is not whether Iran might someday threaten the United States, but whether Iran’s pattern of operations already constitutes a continuing campaign of armed attack.
Iran’s proxy model is designed to normalize aggression below the threshold, blur attribution, and exploit the legal and strategic hesitation that follows. When attacks are launched through intermediaries, or from within dense civilian environments, the goal is often not just physical damage—it is confusion and paralysis. But necessity and proportionality are assessed against the operational reality of an ongoing threat, not against Iran’s preferred narrative that no single strike, taken alone, should “count.”
In that context, the imminence question can also sharpen rather than weaken the self-defense claim. Where intelligence indicates that another attack is being prepared against U.S. assets, a defensive strike can be framed as preventing an imminent armed attack within a broader ongoing campaign, rather than initiating a new war.
Under this theory, the United States is not required to wait until Americans are killed before acting to stop launches that are already being readied.
The broader regional escalation reinforces this defensive context. Iranian strikes have not been confined to Israel; they have also impacted U.S. forces and Gulf Arab states that host American personnel and assets.
Several of these states have condemned Iranian attacks as violations of their sovereignty and retain their own rights to self-defense. While the United States is not intervening on behalf of Gulf states under a formal treaty obligation identical to its support for Israel, the regional pattern of missile and drone attacks contributes to the legal assessment of necessity.
When multiple sovereign states are being struck and U.S. forces are directly targeted, the cumulative threat environment strengthens the claim that American force is aimed at immediate defense rather than abstract strategic policy.
A central debate concerns imminence.
Critics question whether the United States acted in response to a current or imminent armed attack. Proponents argue that Iran’s escalating missile launches, operational posture, and threats indicated a sustained and continuing campaign of armed attack rather than isolated incidents. In such a situation, waiting for a catastrophic strike before acting could undermine the effectiveness of defense and increase harm to U.S. forces and allies.
While this interpretation of imminence is broader than the narrow classical model requiring visible troops massed at the border, supporters contend that modern missile warfare and ongoing hostilities justify a contextual approach. Moreover, because the United States can ground its involvement in collective self-defense of Israel, the imminence question becomes less central than it would be in a purely anticipatory scenario.
States invoking Article 51 customarily report their actions to the U.N. Security Council and publicly articulate their legal basis. U.S. officials have framed their actions within the Article 51 framework, emphasizing coordination with Israel, the collective self-defense rationale, and the destabilizing and aggressive conduct attributed to Iran over time.
By situating its actions within the Charter structure rather than outside it, the United States presents its operations as consistent with established international legal doctrine.
The framing that Israel somehow “pulled” the United States into this war is also inaccurate. The reality is that the United States and Israel share the same strategic objective: ensuring that a regime which openly calls for the destruction of both countries — and has been in open war against both for some time– can no longer threaten either nation.
Given the Iranian regime’s longstanding belligerence toward the United States, its decades of attacks on Americans, and its pursuit of nuclear weapons and increasingly advanced ballistic missile technology capable of threatening the United States and its allies, Washington has a clear interest in stopping Iran’s capabilities from maturing further, especially when the Iranian regime is seeking to move its activities further underground. Acting sooner rather than later reduces the risk that these threats become far more dangerous and far harder to contain.
This is also where the stated objectives matter legally and strategically.
The strongest framing is limited and security-focused: deterring further attacks, degrading networks that target Americans, protecting shipping lanes and chokepoints, and preventing the maturation of capabilities—nuclear and ballistic—that would sharply increase the risk of regional catastrophe.
The argument is not that force is used to overthrow a government for its own sake, but that calibrated strikes are used to reduce the probability of future armed attacks and to restore deterrence against a regime that has repeatedly demonstrated hostile intent and operational follow-through.
The legal basis for American operations is also straightforward. The United States can rely on collective self-defense in support of Israel, a state that has been directly attacked by Iran and Iranian-backed forces. At the same time, Washington retains its own independent right of self-defense considering Iran’s repeated attacks on U.S. personnel, forces, and interests across the region.
Iran’s Record of Aggression The broader strategic record further contextualizes the legal arguments. Iran’s confrontation with the United States and its allies is not new.
Since the Islamic Revolution in 1979, Iran has supported militant proxy networks across the Middle East, including Hezbollah in Lebanon, Hamas in Gaza, and Houthi forces in Yemen.
Iranian-backed groups have killed hundreds of Americans over the decades, from the 1983 bombing of the U.S. Marine barracks in Beirut to attacks against U.S. forces during the Iraq War.
More recently, Iranian-backed militias conducted over a hundred attacks against American bases in Iraq and Syria between 2023 and 2024. Iran itself launched ballistic missiles at U.S. positions in Iraq in 2020 following the killing of Qassem Soleimani. Meanwhile, Tehran continues to expand its ballistic missile arsenal, pursue nuclear enrichment capabilities, and develop longer-range missile technology.
Iran’s destabilizing activities extend beyond direct attacks. The regime has supplied drones to Russia for use in Ukraine, facilitated sanctions-evading oil exports to China, and supported maritime attacks by the Houthis against commercial shipping.
Iran’s repeated threats to close or disrupt the Strait of Hormuz — through which a substantial portion of the world’s energy supply passes — also implicate the security of global commerce and freedom of navigation, further raising the stakes of its military posture.
Iranian officials have repeatedly threatened the Strait of Hormuz, a vital artery for global energy markets, while previously targeting Saudi Arabian oil infrastructure in attacks that temporarily disrupted a significant portion of the world’s oil supply.
Taken together, these actions contribute to what many analysts describe as a sustained campaign of regional coercion conducted through both direct and proxy means.
As a side, the regime’s brutality has not been limited to its adversaries. During the Iran–Iraq War, Iranian leaders mobilized large numbers of teenagers, including young boys, and sent them in human-wave assaults and minefield-clearing operations, often with no training, simply carrying religious symbols such as Qurans and plastic “keys to paradise.” This is also a regime that just brutally murdered thousands – if not over thirty-thousand – of its own citizens in a matter of days this past January.
Nuclear Weapons Raise the Stakes Iran’s nuclear program changes the threat level not because enrichment alone is an armed attack, but because a nuclear-armed Iran would materially alter the strategic and legal landscape in which self-defense must operate.
If Iran obtains nuclear weapons, its proxy model becomes more dangerous under the shelter of a nuclear umbrella, regional proliferation pressures intensify, U.S. and allied military options narrow, and the risk of catastrophic escalation rises.
In that world, every future crisis becomes harder to manage, miscalculation becomes more consequential, and deterrence failures become exponentially more costly. America cannot allow another North Korea to emerge, as once a rogue state has nuclear weapons, it’s too late.
Ending a Campaign of Violence Is Not Starting a War Critics frequently characterize strikes against Iran as acts of “preemption.” But the legal framework is different when a state faces a continuing pattern of armed attacks.
Under Article 51, self-defense may respond not only to a single isolated strike but also to a sustained campaign of violence. Where missile attacks, proxy warfare, and repeated threats form part of a coherent operational pattern, states may treat that series as meeting the armed-attack threshold and act to prevent further attacks.
In that sense, the objective of limited strikes is not punishment or revenge. The objective is degradation of military capability and restoration of deterrence. If missile launchers, command nodes, or proxy coordination networks are being used to sustain attacks, targeting them constitutes a lawful defensive response.
International law’s test is necessity and proportionality — not passivity. The law of self-defense was never intended to require a state to absorb repeated attacks while waiting for perfect clarity about the next one.
Domestic Law: Presidential Authority and the War Powers Resolution The legal debate in Washington also involves domestic constitutional law.
Under Article II of the U.S. Constitution, the president serves as commander in chief of the armed forces and possesses authority to repel attacks and protect American personnel abroad. Presidents of both parties have historically relied on that authority to conduct limited military operations without prior congressional authorization.
This is why the reporting structure matters: the War Powers framework is built around the reality that presidents may need to act first to protect U.S. forces, and then report to Congress after hostilities begin.
In other words, the statute assumes the existence of defensive presidential authority rather than denying it, because the requirement is notification and time-limitation—after forces have been introduced—not a blanket rule of advance permission in every case involving defense of Americans.
The War Powers Resolution of 1973 was enacted to ensure congressional oversight of such actions. It requires the president to notify Congress within 48 hours of introducing U.S. forces into hostilities and limits the deployment to 60 days, with an additional 30-day withdrawal period unless Congress authorizes continued operations.
In practical terms, this means a president may lawfully order limited military action for up to roughly 90 days without a formal declaration of war. Supporters of the current strikes argue that such actions fall squarely within the longstanding understanding of presidential authority to protect U.S. forces and national security interests.
Sovereignty and the Limits of the United Nations Finally, debates about legality often misunderstand the structure of international law itself.
The United Nations is not a world government. The U.N. Charter establishes rules governing the use of force — most notably Article 2(4)’s prohibition on aggressive war and Article 51’s recognition of self-defense — but enforcement remains decentralized. States retain sovereignty.
Under Article 51, the state invoking self-defense makes the initial determination that an armed attack has occurred. Other states and institutions may contest that claim, but the right itself is inherent.
Ultimately, the legal question is not whether force was used, but whether it was used in response to an ongoing pattern of armed attacks. If that standard is applied to Iran’s record of direct strikes, proxy warfare, and threats against both Israel and U.S. forces, the legal basis invoked by Israel and the United States rests squarely within the framework of self-defense recognized by the U.N. Charter.