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International Law News

International Law News, Spring 2024

When Terror Strikes: International Humanitarian Law and Operation Iron Swords

Harry William Baumgarten, Robert E Lutz, Bruce Rashkow, Shira A Scheindlin, and David A Schwartz


  • On October 7, 2023 the terrorist group Hamas launched a brutal attack into Israeli territory where its members killed, tortured, raped, or took hostage over 1,000 Israelis. 
  • Soon afterward, Israel responded with Operation Swords of Iron targeting Hamas operatives and infrastructure deeply embedded in the Gazan civilian population. 
  • This article explores the relevant principles of international humanitarian law that apply to both parties to this conflict.
When Terror Strikes: International Humanitarian Law and Operation Iron Swords
Eddie Gerald via Getty Images

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On October 7, 2023 thousands of Hamas terrorists forcibly entered sovereign Israeli territory where they killed, tortured, raped, or took hostage over 1,000 Israeli civilians and several hundred Israeli soldiers. The Israeli Defense Forces responded with a campaign of aerial strikes, followed by a ground incursion, eventually titled Operation Swords of Iron, targeting Hamas operatives and infrastructure deeply embedded in the Gazan civilian population. According to both Western estimates and Hamas casualty figures, the operation has killed tens of thousands of Gazans, a substantial majority of whom are believed to be civilians. The following is an explanation of relevant international legal principles as they relate to the October 7 terrorist attack and Israel’s response.

International Law Relevant to the Conflict

International Humanitarian Law (IHL) is the body of international law that governs the conduct of armed conflict. It is found in treaties such as the four Geneva Conventions of 1949 and in customary international law, i.e., general and consistent state practice observed due to a sense of legal obligation. Among other objectives, IHL seeks to limit unnecessary suffering during armed conflict, preserve the professionalism and humanity of combatants, and facilitate the restoration of peace.

Because Hamas is a non-state actor, the legal status of Gaza is contested, and Israel is a party only to certain IHL treaties, there is substantial debate about whether several IHL principles apply to the present Israel-Hamas conflict in Gaza. Nonetheless, there is widespread consensus that certain rules of IHL apply universally, regardless of whether a participant in a conflict is a state or a non-state actor, or whether the participant is a party to any particular treaty. Those rules include the requirements of Common Article 3 of the 1949 Geneva Conventions, which has been ratified by every state in the world, and other principles of customary IHL overwhelmingly acknowledged by states across the world.

The Relevant Principles of International Law

Common Article 3 of the 1949 Geneva Conventions, which indisputably applies both to Israel and to Hamas, requires all parties engaged in the current conflict to treat humanely all people who take no active part in the hostilities. With respect to these non-combatants, the provisions of Common Article 3 expressly prohibit “violence to life and person,” “[o]utrages upon personal dignity, in particular humiliating and degrading treatment,” and “cruel treatment and torture.” Murder, rape, and the taking of hostages are all prohibited.

Customary IHL likewise prohibits using human shields and intentionally locating military operations in close proximity to civilian facilities. While states have the right to engage militarily in acts of self-defense, states must conform to the rules established by international law regarding armed conflict, including the principles of distinction and proportionality. The principle of distinction means that belligerents have an obligation to direct attacks only against combatants and military objectives and not to intentionally target civilians or civilian objects, such as schools, houses of worship, or medical facilities, so long as these objects are not used for military purposes. Similarly, belligerents are prohibited from using starvation of the civilian population as a method of warfare, or from deliberately targeting “objects indispensable to the survival of the civilian population” as such.

Consistent with the principle of distinction, civilian facilities can lose protected status under IHL if it is clear that they are being used for military purposes. For example, a hospital or school may become a legitimate military target if it contributes to a party’s military operations, such as serving as a weapons depot or housing fighters who do not require medical attention. To prevent this from happening, parties are not permitted to locate military facilities in close proximity to hospitals. If a hospital becomes a legitimate target, the opposing party must still attempt to protect any civilians present by conforming to the requirements of proportionality.

The principle of proportionality provides that combatants must refrain from a specific military attack if the expected loss of civilian life or injury to civilians, incidental to the attack, would be excessive in relation to the concrete military advantage expected to be gained. This analysis focuses on the combatant’s understanding based on the information reasonably available before the military operation has been effected; the proportionality of a strike thus turns on assessing both the extent of the anticipated civilian harm and the concrete military advantage the combatant expected to achieve before undertaking the specific military operation. There is no formula for determining whether the expected value of a military target justifies the expected harm to civilians. But the required analysis confirms that, under international law, collateral civilian harm is understood to be a tragic but often inevitable consequence of warfare. Whether such harm to civilians violates international law depends on conformity with the principle of proportionality.

The international legal principles of distinction and proportionality apply to all participants in warfare irrespective of whether one or both sides has violated them. Whether specific military operations accord with these principles is a fact-driven inquiry. A proper analysis of whether operations comply with IHL necessarily involves knowledge of the direct military objective that was expected to be achieved by a specific action and the extent of harm to civilian life and property that was anticipated based on the information available before the action was undertaken.

Application of the Relevant Principles of International Law

Applying these and other relevant international legal principles to the current conflict leads to the following findings:

  • Hamas’s deliberate killing of civilians, hostage-taking, rape, torture, and other inhumane treatment of Israeli and other civilians on October 7 constitute war crimes.
  • Consistent with Article 51 of the UN Charter, Israel has the inherent right to conduct military actions in self-defense, and in doing so it is obligated to observe international humanitarian law, including the principles of distinction and proportionality.
  • Hamas’s use of hospitals, schools, mosques, ambulances, and other civilian facilities for military purposes, and its construction of military facilities in tunnels underneath or otherwise in proximity to such facilities is prohibited, and may result in those facilities becoming legitimate targets provided Israel complies with the principle of proportionality.
  • In light of Hamas’s established use of civilian and protected facilities for military purposes, the question of whether Israeli strikes may have violated the principles of distinction and proportionality requires evidence of what Israeli commanders believed about their targets, what they intended to achieve by striking those targets, as well as the measures the Israeli commanders took to minimize civilian casualties in making the strikes in question. Absent such evidence, any assessment of proportionality would be flawed and incomplete.
  • Although some have asserted that the high number of reported Palestinian civilians killed indicates that the Israeli military has violated the principle of proportionality, violations of IHL cannot be determined based on partial information, such as reported casualty counts. Instead, any such assessment must depend on reliable information concerning anticipated or actual civilian casualties, the anticipated military value of particular targets, and the availability of less harmful alternatives.
  • International aid organizations have warned of imminent famine in Gaza and placed much of the blame on Israel for slowing or limiting the flow of humanitarian aid in Gaza. Israel insists that it permits substantial aid to enter Gaza and that the primary obstacle is distribution within Gaza, namely that Hamas and armed gangs are diverting aid or deliberately causing starvation to achieve propaganda aims. Insofar as any party is engaged in a deliberate policy of starving civilians, that constitutes a violation of the IHL.
  • No principle of international law requires comparable casualty counts, civilian or military, of the sides to an armed conflict.


Based on the foregoing analysis of fundamental norms of international law and related findings, we believe the following recommendations should be adopted by all parties to this conflict:

  • All parties to the conflict must comply rigorously with international humanitarian law, particularly with regard to the protection of civilians.
  • Hamas should immediately and unconditionally release all hostages and cease all incursions and rocket-fire into the sovereign territory of Israel.
  • The legal community should reject the fallacy of IHL equivalence between civilians forcibly kidnapped by Hamas and held without justification or legal process, and Palestinian prisoners in Israeli jails convicted of terrorist acts or held pursuant to legal process, security justification, and with access to humanitarian services.
  • Hamas should immediately cease using Gazan civilians as human shields, preventing residents of Gaza from leaving the areas in which Hamas has placed its soldiers and weapons, and locating and operating military equipment, camps, and headquarters in, near, or underneath civilian locations such as mosques, schools, and hospitals.
  • Consistent with the appropriate exercise of military force otherwise authorized under IHL, Israel should do everything possible to protect civilians and civilian objects from the effects of the conflict. Israel should make additional efforts to allow supplies of humanitarian aid to Gazan civilians, including food, water, medical supplies, and fuel, provided it can be reasonably assured that such aid will not interfere with its immediate ongoing military operations and will not be diverted by Hamas or others for military purposes. Efforts by credible parties to airdrop humanitarian supplies or deliver them to Gaza’s civilian population by sea in coordination with Israel are also justified.
  • Based on the current, publicly available record, the legal community should not assert that Israel is engaged in war crimes in Gaza without fairly and objectively examining whether and to what extent credible and reliable bases exist for such a conclusion.

Both Israelis and Palestinians have already suffered tragically due to the horrific and unjustifiable attack of October 7th. However, one matter remains clear. The rigorous application of international humanitarian law is essential to prevent rewarding brutal aggressors and to help ensure a future peace.