Israel’s Excessive Destruction in Gaza Violates International Law

Several months after breaking the ceasefire, Israel has embraced a new, even more ambitious phase to its war against Hamas in Gaza. Israeli officials have indicated that in this phase, dubbed Gideon’s Chariots, Israel is looking to assert control over all of Gaza. This phase has been marked by what experts have called mass starvation, along with a growing chorus of nongovernmental organizations and genocide scholars deeming the ongoing war in Gaza a genocide against the Palestinian people. While the genocide determination remains contested, what is beyond dispute is that Israel has caused enormous devastation in Gaza. Its insistence that, to achieve its self-defense, it must fully defeat Hamas’s military wing and remove Hamas from any political control of Gaza is prolonging the war and hampering the quest for a lasting ceasefire. It has also resulted in a military campaign that violates international law, going beyond what is permitted for using force in self-defense.

As we argue in a forthcoming law review article, it was impermissible for Israel to pursue this strategic objective in the first place, let alone keep pursuing it. Given the conditions prevailing in Gaza, it was clear even in the immediate wake of the brutal Hamas-led Oct. 7, 2023, attacks against Israel that Israel could not achieve this objective without causing excessive harm in Gaza, in violation of the principle of jus ad bellum proportionality that governs states’ uses of force.

Ceasefire negotiators and policymakers in states allied with Israel should reject Israel’s insistence on preserving the right to pursue this objective as a valid exercise of self-defense. Instead, they should pressure Israel to abandon this strategic objective and finally end the war, namely by halting forms of security cooperation with Israel that are assisting Israel’s use of excessive force in Gaza.

The Legal Scope of Israel’s Right of Self-Defense

Under international jus ad bellum rules, states that use armed force must not only have a permissible legal basis for doing so. They must also ensure that the scope and intensity of their force is proportionate, or not excessive in comparison to their legal justification for using force. While Israel has invoked the former legal right, it has ignored the latter legal duty. Israel has relied on a flawed interpretation of international law to engage in excessive, and therefore unlawful, use of force in Gaza. States and policymakers that support Israel have recognized Israel’s right of self-defense but have often failed to account for how Israel has pursued its self-defense. By ignoring this, their security cooperation has fueled Israel’s use of excessive force and, thus, Israel’s violation of international law.

Israel’s Right of Self-Defense, the Principle of Proportionality, and the Legitimate Goals of Self-Defense

Permissible legal bases to use force under modern international law are (a) in individual or collective self-defense or (b) under UN Security Council authorization. In this case, Israel has asserted self-defense as the legal basis for using force against Hamas in Gaza. While there are debates about some aspects of Israel’s claim of self-defense in this case, the more substantiated legal argument is that Israel had a right to use force in self-defense following the Hamas-led Oct. 7, 2023, attack.

However, Israel’s right of self-defense does not grant it the right to use an unrestricted amount of force. Under the long-standing jus ad bellum principle of proportionality, the scope and intensity of the force Israel employs must not be excessive in relation to its overall goal of self-defense.

Admittedly, this formulation of proportionality raises a preliminary consideration around defining the goal of self-defense. How can one measure what is excessive if there is no clarity around what force in self-defense can permissibly be used to achieve? Legal scholars have disagreed about this. Some maintain that self-defense only allows states to repel an ongoing attack, while others interpret self-defense as allowing a state that has been attacked to use force to confront tangible continuing threats from an adversary, even if the attack has already been completed. Based on our own assessment of state practice and existing legal scholarship, and drawing from just war theory, we contend that a state that has sustained an armed attack may seek to restore reasonable levels of security by reducing tangible threats of future attacks from that aggressor. A state may not, importantly, seek to achieve a perfect level of security. Nor may a state use force in self-defense where there is no tangible threat of a future attack, as this would amount to retribution.

Thus, any state’s use of force in self-defense—including Israel’s—must not be excessive in relation to restoring a reasonable level of security by reducing tangible threats of future attacks. This applies both when a state is determining its strategic objectives and throughout the warfighting endeavor. To assess whether a state’s use of force is excessive, the scope and intensity of force are relevant. For scope, states, international courts, and scholars have looked at the geographic area or duration of the war. For intensity, they have considered the overall level of damage or destruction, harm to civilians—including civilian casualties and damage to infrastructure civilians rely on for their survival—or, in some instances, environmental damage.

This is not a novel understanding of the right of self-defense but, rather, is a well-accepted, long-standing principle of international law, and one that states are well aware of. Several of Israel’s allies have correctly publicly stated that Israel’s right of self-defense must be exercised within the confines of international law, and some have specifically referenced proportionality as a component of Israel’s use of force in self-defense against Hamas in Gaza. Some scholars, too, have pointed out that Israel’s right of self-defense is not unlimited and is subject to the constraints imposed by proportionality. Even some who have defended Israel against allegations that its war in Gaza has been overly aggressive or indiscriminate have correctly noted that proportionality plays a critical role in assessing the legality of Israel’s conduct.

Israel Has Caused Excessive Harm in Its War Against Hamas in Gaza, in Violation of the Requirements of Proportionality

There is little legal disagreement about whether proportionality applies to Israel’s use of force in self-defense in Gaza. The real legal question is: Has Israel complied?

We investigated this question, focusing on the first year of Israeli military operations in Gaza (dubbed “Operation Swords of Iron” by Israel). We find that while Israel’s stated strategic objective fell within the legitimate boundaries of self-defense, the intensity of force required to carry it out in Gaza was foreseeably excessive, thus rendering the objective impermissible under international law. The actual conduct of military operations has borne out what should have been foreseen before the operations commenced: Israel’s use of force in Gaza has been excessive in relation to its overall self-defense aim.

Israel’s Strategic Objective Is Legitimate …

Israel’s official stated strategic objective, which is to eliminate Hamas’s military capabilities and remove it from political power, falls within the legitimate boundaries of self-defense (for example, reducing tangible threats of future attacks to restore a reasonable level of security). Although this objective is undeniably far-reaching, the circumstances of this conflict indicate that Hamas has displayed credible and significant threats of tangible future attacks on Israel. It had demonstrated this by a history of prior attacks, articulation of objectives widely believed to reflect a commitment to the destruction of Israel, and promises to carry out future attacks like the attack on Oct. 7. These considerations justify such a far-reaching strategic objective. (In addition to this strategic objective, Israel identified securing the return of the hostages as an additional strategic objective in its war against Hamas. Given that this is a far more modest objective, we focus on the more expansive objective, assuming the less expansive is perforce legitimate).

… But the Means Required to Carry It Out Were Foreseeably Excessive, Rendering It Impermissible

Even though Israel’s strategic objective of eliminating Hamas’s military capabilities and removing it from political power can be viewed as legitimate, Israel’s use of force after Oct. 7, 2023, was still subject to the requirements of proportionality. In other words, Israel’s strategic objective could not be lawfully pursued if the intensity of the means required to carry out this objective would cause excessive damage and harm to civilians.

Here is where Israel’s conduct ran afoul of the requirements of international law. Israel should have anticipated even before it launched Operation Swords of Iron that it could not achieve this strategic objective without causing excessive damage and harm to civilians. Israeli officials knew before they launched Operation Swords of Iron that Gaza is a small military theater that is densely populated and has limited areas for civilians to flee or seek safety, that Hamas has integrated its military capabilities within the Gazan civilian population (to be sure in some cases in violation of the prohibition on the use of human shields under international humanitarian law), and that Hamas has built an extensive network of tunnels believed by Israeli intelligence to stretch throughout Gaza. These factors should have made clear to Israeli officials from the beginning that the strategic objective of eliminating Hamas’s military capabilities and removing it from political power would be impossible to achieve without causing a level of damage and civilian harm that was excessive in relation to its self-defense interests. Israel violated jus ad bellum proportionality by deciding to pursue these objectives in the first place, before Israeli forces even entered Gaza.

To be clear, in making this argument, we are not advancing a view of international law as a suicide pact. The fact that Israel could not, in compliance with the principle of proportionality, pursue the far-reaching strategic objective it announced does not mean Israel had no ability to defend itself. Seeking to eliminate Hamas’s military capabilities and remove it from political power was by no means the only option available to Israel to ensure its self-defense, as senior U.S. military experts who had participated in U.S. counterinsurgency urban warfare operations in Iraq advised Israeli officials in the immediate aftermath of the Oct. 7, 2023, attacks.

Israel Used Force in Gaza That Violated Proportionality

We collaborated with geospatial experts to assess the intensity of Israel’s warfighting during Operation Swords of Iron. Our co-authors found by mapping damage to the built environment in Gaza that by the end of October 2024, Israeli forces had damaged or destroyed nearly 60 percent of all buildings in the Gaza Strip. The rate of damage was particularly concentrated in the north of Gaza, where more than 70 percent and 74 percent of buildings in the North Gaza and Gaza governorates, respectively, had been damaged or destroyed.

This level of damage is not a normal incidence of war, as demonstrated by looking at other modern, highly destructive wars. In Mariupol, Ukraine, one of the most heavily targeted cities in a war that reputable scholars have characterized as involving disproportionate force, 32 percent of buildings were damaged or destroyed during Russia’s siege and heavy fighting for control over the city in 2022. This is roughly half the amount of damage tracked in Gaza over roughly the same amount of time. In Aleppo, Syria, a contested city in a civil war condemned as one of the most destructive wars in modern history, more than 40 percent of buildings were damaged during three years of war, compared to the nearly 60 percent damaged in Gaza after one.

Israel also caused significant damage to infrastructure necessary for civilian survival in Gaza, similarly outpacing rates of damage to critical civilian infrastructure in other modern urban conflicts (see, for example, Syria and Ukraine). By the summer of 2024, less than a year after Operation Swords of Iron began, 94 percent of all health facilities and 84 percent of all water, sanitation, and hygiene (WASH) facilities across Gaza had been damaged or destroyed. Other damage patterns indicated that Israeli forces clustered damage around civilian infrastructure rather than away from it.

Such levels of damage to the built environment in Gaza and to infrastructure necessary for civilian survival go well beyond what was proportionate to the reduction of tangible threats of future attacks from Hamas and restoring a reasonable level of security for Israel. Nor does Israel itself appear to dispute that the level of damage in Gaza was extraordinary. During the first month of the war, Israeli officials announced that they were focused on imposing “maximum damage” in Gaza.

Disproportionate Force Causing Excessive Harm Has Continued Unabated

Israel’s military operations since the October 2024 endpoint of our findings have continued, officially in furtherance of eliminating Hamas’s military capabilities and removing it from political power. In doing so, those operations have continued to inflict excessive harm in Gaza. Under Operation Gideon’s Chariot, which was announced on May 18 (after Israel in March ended a ceasefire that had been in effect for two months), Israel launched an even more far-reaching plan for Gaza that involves “raz[ing] most buildings” and occupying Gaza “for the foreseeable future.”

The result has been even greater destruction, with devastating consequences for Gaza and the Palestinian people who live there. Nearly 78 percent of all structures in Gaza have now been destroyed. Ninety-four percent of all hospitals in Gaza have been damaged or destroyed, and while damage rates to WASH facilities have not yet been published, theUnited Nations Office for the Coordination of Humanitarian Affairs reported in May that more than 90 percent of households are water insecure and 73 percent of all WASH facilities are in Israeli-designated military zones, rendering them inaccessible to the Palestinian civilian population.

The continued destruction of Gaza and harm to civilians is clearly excessive, and thus impermissible, in relation to reducing tangible threats of future Hamas attacks under jus ad bellum proportionality. Even though Israel has the right to use force in self-defense in response to the Oct. 7, 2023, attacks, this does not grant it a carte blanche to destroy Gaza.Israel is violating international law by employing means that are doing so, in pursuance of its professed strategic objective.

Israel’s Insistence on Pursuing Its Illegal Strategic Objective Is Impeding a Lasting Ceasefire

Israel’s insistence on pursuing its strategic objective of eliminating Hamas’s military capabilities and removing it from political power not only violates international law but also prevents the establishment of a lasting ceasefire. While U.S. officials have announced progress in ceasefire discussions, a continued obstacle is Israel’s unwillingness to definitively renounce the possibility that it will resume hostilities in order to achieve its professed objective. Hamas, in contrast, seeks assurances that any ceasefire it agrees to will result in a definitive end to hostilities.

Apart from the obstacles Israel’s strategic objective poses for ceasefire negotiation, it is difficult to see how Israel could ever achieve that objective. Israel’s failure to eliminate Hamas’s military capabilities and to completely remove it from political power after nearly two years of brutal conflict suggest that Israel’s strategic objective is likely impossible to achieve. Israel’s pursuit of its strategic objective is not only legally impermissible but is also impeding a ceasefire to end the current conflict in Gaza. Israel must be pressured to stop  insisting on reserving the possibility of continuing hostilities, and permanently end the war.

An Urgent Need for International Actors to Meaningfully Press Israel to End Its Illegal Actions

There is growing recognition among many of Israel’s allies that its current use of force in self-defense is disproportionate. In mid-May, France, the United Kingdom, and Canada issued a joint statement in which they referred to Israel’s current operations in Gaza as “wholly disproportionate” and expressed strong opposition to “the expansion of Israel’s military operations in Gaza,” a sentiment further echoed by Kaja Kallas, the EU’s high representative for foreign affairs and security policy. Germany, a long-standing ally of Israel, has also expressed increasing concern. In mid-June, Chancellor Friedrich Merz told a German public broadcaster that “harming the civilian population to such an extent … can no longer be justified as a fight against Hamas terrorism.” Other states and policymakers similarly raised concerns about Israel’s disproportionate use of force during Operation Swords of Iron.

In the United States, 15 senators voted for two resolutions that would have canceled the sale of $8.8 billion in large bombs and other munitions to Israel. Sen. Andy Kim (D-N.J.) observed that while he supports Israel’s right to self-defense, he does not believe that these weapons, which can “level entire city blocks and that have been used in incidents with disproportionate civilian casualties, achieve the primary objectives” of Israel’s self-defense.

Even prominent Israelis have raised concerns. Former Israeli Prime Minister Ehud Olmert penned an influential op-ed in the Israeli news outlet Haaretz in which he argued that what Israel is doing right now in Gaza is “a war of devastation,” and that the war’s continuation has been without justification, accusing the Israeli military of acting “over-aggressively” in Gaza. In addition, 41 Israeli intelligence officers and reservists accused the government of waging an “unnecessary, eternal war” in Gaza.

Our research findings should embolden states, policymakers, and civil society actors to demand that Israel cease carrying out its current military campaign in Gaza, which violates jus ad bellum proportionality. Such a demand does not, as outlined above, undermine Israel’s right of self-defense, and policymakers should be unafraid to oppose the current conduct of Israel’s war in Gaza even as they support Israel’s right of self-defense. Upon acknowledging that Israel is carrying out its military campaign in Gaza in violation of the principle of proportionality, allied states should take meaningful and concrete steps both to discourage Israel from continuing its illegal conduct and to limit their own potential complicity in such conduct by halting security cooperation with Israel that will foreseeably assist Israel’s excessive force in Gaza. At minimum, this means refusing to authorize further transfers of, and cancelling shipments or licenses for, weapons that are enabling Israel’s use of excessive force in Gaza.

Beyond tangible action, state officials should also continue to speak out on this issue. They should profess on the record, either in unilateral public statements or in UN proceedings, that Israel’s actions are excessive or disproportionate under jus ad bellum proportionality. In the U.S., this could happen through House or Senate declaratory resolutions that, even if nonbinding, carry symbolic weight. This contributes to the body of state practice, which is used by lawyers to interpret the boundaries of the law. In addition, states could encourage the UN General Assembly to seek an advisory opinion from the International Court of Justice on the matter, which could provide further guidance for future state behavior, although it is unlikely to be effective in curtailing Israel’s conduct in the short term. Additionally, journalists and academics should report on Israel’s use of force in Gaza as disproportionate and excessive to correctly inform the public on this issue.

Finally, as noted above, ceasefire negotiators should demand that Israel accept a lasting ceasefire deal that does not involve Israel’s continued pursuit of eliminating Hamas’s military capabilities and removing it from political power.

Israel may need to accept that it cannot achieve what it views as perfect security without violating international law. But its inability to accept this to date has resulted in intolerable devastation for Palestinians in Gaza, along with growing international isolation of Israel. It is necessary—and well past time—to end the current hostilities.