When it comes to the laws of war, a substantial number of commentators can play the notes but not the music. This essay examines the Hamas-Israel War in light of this ever-evolving body of law. The set of rules has grown from wars and conflict over the last 500 years and is at least partly reflected in codification efforts in the last century. This history explains why little in the Hague or Geneva Conventions (or Protocols) is absolute. The laws of war reflect the unsolvable tension between military necessity and the need to limit engagement with civilian populations. In no conflict has urban warfare been pretty or quick. It is with both feet in this reality that one should consider what the law is and how to apply it. Our verified knowledge of the situation and fighting in Gaza is limited.[1]

I. Relevant International Law

Israel’s authority to use force and conduct military operations is rooted in international law. Hamas is an armed band and has no legal authority under international or any other law to engage in attacks against Israel and Israelis, including specifically the kind of attacks it favors—missiles launched at civilian targets, terrorist attacks on civilians, and other efforts using force to destroy the State of Israel.[2]

The relevant international law has two parts—the law governing the resort to force or the jus ad bellum and the law governing military operations during the conflict, the jus in bello.[3] Both use similar terms to summarize their requirements—“necessity” and “proportionality”—but with different meanings. The jus ad bellum requires that a State’s use of force in self-defense be necessary: “necessity” means that there is no reasonable alternative to a use of force to achieve the goals of self-defense, namely, the termination of the situation giving rise to the right to use force in self-defense in the first place. It is the last reasonable resort. “Proportionality” in this context flows naturally from “necessity:” it is the minimum force reasonably required to bring an end to the situation giving rise to the right of self-defense and to prevent its recurrence. The ideal of economy of force is embedded in notions of proportionality.

The lawful purposes encapsulated in the right to use force in self-defense inescapably influence the conduct of military operations and the application of the jus in bello. Under the jus in bello, necessity means military necessity—the advantage to be attained by attacking a particular military target. The jus in bello standard to which everybody points is set forth in Article 57 of the 1977 Protocol I Additional to the 1949 Geneva Conventions: “those who plan or decide upon an attack shall … refrain from deciding to launch any attack which may be expected to cause incidental loss of civilian life, injury to civilians, damage to civilian objects, or a combination thereof, which would be excessive in relation to the concrete and direct military advantage anticipated.” States, even those States such as Israel and the United States that are not parties to the Protocol, accept this statement as accurately reflecting customary international law binding on all States. Proportionality means that commanders must weigh the advantage from attacking the target against possible or reasonably foreseeable civilian or other collateral damage. At the same time, the selection of military targets and the determination of their importance are made in the context of efforts to achieve the lawful purposes of the use of force.

II. Hamas-Israel War

Hamas has waged war against Israel almost continuously since the Gaza elections in 2006 made it the governing authority in the Gaza Strip. To celebrate its election victory, Hamas launched missiles against Israel, captured Gilad Shalit, an Israeli soldier, and attacked Israeli civilians.[4] Hamas has repeated such attacks almost continuously since then. Substantial conflict erupted on four occasions before October 7, 2023: 2008, 2012, 2014, and 2021. In each case, Israel’s strategic choices were difficult, and the use of force against Hamas was one lawful option.[5]

Hamas’s stated goals include the elimination of Israel.[6] In context, that is a genocidal goal, completely at odds with, and in violation of, international law. On October 7, 2023, Hamas forces invaded Israel and launched barrages of missiles at Israel from cites within highly populated urban areas of the Gaza Strip. Hamas instructed its fighters, literally, “Kill as many people and take as many hostages as possible.” Hamas directed the attacks from a system of subterranean tunnels under cities, mosques, hospitals, schools, and other civilian centers in the Gaza Strip. With or without the consent of the governed, Hamas already had turned the Gaza Strip into an urbanized fortress, which could not be attacked without causing substantial destruction and casualties. In fact, the purpose of Hamas’s actions on October 7, 2023 was to ensure that Israel would attack Hamas fighters in the urban context of Gaza. This Hamas strategic decision itself violated jus in bello prohibitions on locating military installations in or near civilian infrastructure of whatever kind. The continuing attacks confronted Israel with no alternative to a use of force against Hamas with the object of putting an end to the attacks. No diplomatic, international effort has been successful in trying to persuade Hamas to give up its goals and determination to fight and destroy the State of Israel and its Jewish inhabitants (notwithstanding the 2017 Hamas Charter statement that Hamas’s “conflict is with the Zionist project not with the Jews because of their religion”). No such diplomatic effort today has a reasonable chance of success. The most international diplomacy has achieved with respect to the series of Hamas-Israel conflicts since 2006 has been ceasefires, which, rather than being a prelude to peace, only have allowed Hamas to rebuild its forces and attack once again.

Israel’s use of force against Hamas has had a number of related objectives and characteristics. The foremost goal has been the elimination of Hamas as a demonstrated, continuing, lethal threat to Israel and innocent Israeli civilians. Hamas does not regard such Israelis as innocent. That is the message of the Hamas Charter as a whole. In this long Hamas-Israel conflict, tunnels have proved essential to Hamas’s ability in secret to arm itself, manufacture weapons and maintain weapons caches, establish command and control centers, and hide and launch missiles at Israel. Destruction or at least neutralization of those tunnels is a reasonable and lawful military objective.

Hamas has raised the use of civilian cover for military operations to a high art. The tunnels run throughout the Strip, beneath civilian population centers, below mosques and other religious structures, beneath hospitals and schools. Often, entrances are built into those structures. As one report put it, the tunnels compound “the immense difficulties of fighting in a dense urban environment.”

As a matter of law, any civilian facility that is repurposed for military use, whether an apartment building, a house of worship, a hospital, or a school, loses its civilian status and becomes a lawful target if its importance warrants targeting. Proportionality constraints operate but the enemy force has put remaining non-combatant civilians at risk. In the present conflict, Hamas has used all of these and other civilian structures to advance its military goals. The most notorious example is the case of the al-Shifa hospital, now recognized by U.S. declassified intelligence and other sources as linked to the tunnel system and used as an Hamas command center until only “shortly before” the Israeli military went in. (In the 2014 conflict, Amnesty International reported that “Hamas forces used the abandoned areas of al-Shifa hospital in Gaza City, including the outpatients’ clinic area, to detain, interrogate, torture and otherwise ill-treat suspects.”)

The use of civilian structures for military operations transforms them into military objects that lawfully can be attacked. Civilians who volunteer to assist military operations from such repurposed structures lose their civilian status. (Militaries tend to identify people as combatants or non-combatants, which clarifies status for operational purposes.) Using civilian structures for military purposes inevitably puts all other civilians at risk because the military purpose makes the structure, as in the case of Israel’s conflict with Hamas, a lawful and important military target. In the urban warfare being conducted in the particular facts relating to Gaza, Israel’s use of force necessarily involves destruction of infrastructure as part of attacks on Hamas’s tunnel system and, as a matter of international law, depending on the circumstances that would make an attack reasonable or unreasonable, would not be “excessive in relation to the concrete and direct military advantage” that Israel anticipates. The fact that a commander may not be certain about the actions of civilians that were civilian but have now become legitimate military targets compounds the difficulty of battlefield decision-making.[7] As General Wolfe, the victor on the Plains of Abraham, wrote in the eighteenth century, war “is an option of difficulties.”[8]

In its effort to destroy Hamas’s tunnel system and structures, Israel has inflicted enormous physical damage on the Gaza Strip. While not even Israel disputes that there also have been substantial numbers of civilian casualties, claims by Hamas that Israel has killed more than 20,000 civilians and fighters are impossible to verify at this time. In past Israel clashes with Palestinians, casualty claims made during the course of operations have not been substantiated by subsequent investigation.[9]

Documentation is widespread of Israeli efforts to warn Gazans of impending attacks, urging them to leave specific areas and otherwise take cover. Such warnings comply with customary international law requirements to distinguish between civilian and military targets and to take all “feasible” steps to ensure that targets are not civilian and to protect the civilian population.[10] Israel’s efforts in this regard are public. The problem is that Gazans have few options with respect to leaving the scene of battle because Hamas has so constructed its military infrastructure as to be almost inseparable from the civilian population of Gaza itself.[11] It is hard to escape the conclusion that maximizing civilian casualties among Gazans so as to make Israel appear legally and morally culpable is a Hamas strategic goal. Multiple statements by the group’s senior officials support that assessment. One of the most notorious was by the group’s leader Ayman Shanaa in a television interview in late November. He said, “Let us examine history. Let us look at Algeria, Vietnam, and other countries that we liberated. How many did they sacrifice? Millions of martyrs. Therefore, I am saying that there is a high price to pay on the path of resistance, and we will bear this price.” In addition, since 1948, successive Egyptian governments have insisted that the Gaza Strip is not part of Egypt even while they administered it and refused to allow Gazans to move to Egypt.


War is not a game. Urban warfare makes especially difficult the process of evaluating costs and benefits and reaching reasonable conclusions about target selection. Efforts to notify inhabitants of an area for targeting so that they can move out of the way are characteristic of Israeli methods of warfare and consistent with contemporary international law set forth in treaties that accurately reflect customary international law. In the case of the current Hamas-Israel conflict, Israel has told civilians to move out of harm’s way; at the same time, Hamas and to some extent Egypt have impeded the ability of such civilians to move.

By turning so much of Gaza into a fortress, laced with tunnels containing command centers and weapons and through which troops move on their attack vectors, Hamas intentionally has put civilians at risk. Doing so does not mean Israel’s use of force against Hamas is disproportionate, much less, as the South African submission to the International Court of Justice claims, genocide. Hamas’s celebration of Palestinian casualties and calculated acceptance of physical destruction in Gaza brought on by its own actions against Israel, make clear than any alternative to Israel’s campaign must protect Israelis and Palestinians from Hamas.


[1] The starkly different Israeli and South African accounts of the source of much of the infrastructure damage in Gaza and the identity of the known dead before the International Court of Justice on January 11 and 12, 2024, drive this point home.

[2] Hamas is not a State. It therefore does not possess a right of self-defense. The UN Charter affirmation of the right of self-defense is clear on the point: “Nothing in the present Charter shall impair the inherent right of individual or collective self-defence if an armed attack occurs against a Member of the United Nations, until the Security Council has taken measures necessary to maintain international peace and security.” UN Charter Art. 51. Only States may be members of the United Nations. Id. at Art. 4.

[3] Jus in bello is supposed to be interchangeable as a term with “the laws of war,” “the law of armed conflict,” and “international humanitarian law.” The Latin term and “the laws of war” focus attention on the fact that, as the St. Petersburg Declaration of 1868 put it, the goal is “alleviating as much as possible the calamities of war; [and] That the only legitimate object which States should endeavor to accomplish during war is to weaken the military forces of the enemy.” In contemporary jus in bello, this Declaration is regarded as the source of the notion that means of warfare causing unnecessary suffering are prohibited. Adam Roberts & Richard Guelff, eds., Documents on the Laws of War (Oxford: Oxford University Press, 2nd ed., 1989), 29. Terms like “international humanitarian law” introduce unnecessary confusion about the boundary between international human rights law and the laws of war. Therefore, this essay uses the Latin, jus in bello, because it emphasizes that the laws of war govern the specific subject of military operations. See also W. Michael Reisman & Chris Antoniou, eds., The Laws of War (New York: Vintage Books, 1994), xxi-xxii.

[4] After 5 years, Hamas exchanged Shalit for more than 1,000 prisoners in Israeli jails. Gershon Baskin, “I Negotiated Israel’s Hardest Hostage Deal: Here’s What’s Next in Gaza,” The New York Times, Oct. 21, 2023.

[5] See Michael Oren, “How Gaza Became Israel’s Unsolvable Problem,” Mosaicmagazine.com, June 7, 2021.

[6] See the 2017 version of the Hamas Charter (e.g., Arts. 14-23, among other things declaring the nullification of all international legal documents underpinning the existence of the State of Israel (the “Zionist Project” in the words of the Hamas Charter). For a discussion about how Hamas changed its charter as a matter of tactics and strategic rebranding, see Colin P. Clarke, “Hamas’s Strategic Rebranding,” TheRANDBlog, May 17, 2017.

[7] See, e.g., U.S. Department of Defense, Law of War Manual (Updated July 2023) at §

[8] James N. Wolfe to William Rickson, Nov. 5, 1757, Beckles Willson, The Life and Letters of James Wolfe (London: William Heineman, 1909), 339.

[9] The 2002 Jenin episode is a cautionary tale. Israel was accused of causing at least 1,000 Palestinian deaths. The reality turned out to be fewer than 60. See, e.g., Martin Sieff, “How Europe’s Media Lost Out,” UPI, May 5, 2002; Mark Steyn, “The UN is Running Out of Blind Eyes to Turn,” The Daily Telegraph, Apr. 20, 2002.

[10] See, e.g., Protocol I, supra note 3, at Arts. 57-58. See also the U.S. construction that this requirement shall be applied reasonably. U.S. Dept’t of Defense, Law of War Manual, supra note 7, at  §5.14.

[11] That population is estimated to be about 2 million or more. No census seems ever to have been taken.


Photo credit: Israeli soldiers guarding a barrier (Getty Images/Joel Carillet)