The Laws of War

Each day brings new accounts of tragedy from Israel and Gaza. Reasonable people agree that the atrocities Hamas committed on October 7—deliberate, videotaped killings of innocent civilians; maiming in the most gruesome fashion of Israeli women and children; and taking Israelis as hostages into its warren of tunnels—stand as deeply disturbing violations of human rights and the laws of armed conflict. As President Joe Biden made clear, Israel possesses a right of self-defense that legally justifies the use of force against Hamas to prevent further atrocities and missile launches against its civilians. Those who argue Israel does not have a right of self defense make two claims: First, they argue that Israel’s “inherent right” is nullified because it is the “occupying power” of the Gaza Strip; and, second, they argue that the right of self-defense in Article 51 of the UN Charter applies only to force against other states, not non-state actors like Hamas. 

Both arguments are unavailing. It is highly doubtful that Israel qualifies as an “occupying” power of the Gaza Strip because once it withdrew all military forces from Gaza in 2005, it has exercised no authority over the territory, which is a requirement under international law before assuming the responsibility of an occupying power. UN groups like the Human Rights Council counter that the status of “occupier” still applies because Israel has imposed stringent limits on travel to and trade with Gaza. And yet Egypt has (mostly) sealed off Gaza’s other border without being termed an occupying power. 

In any event, even if Israel were an occupying power, that status would not justify Hamas' intentional attacks on civilian targets in Israel or prevent Israel from using force to protect itself. For example, it was not considered illegal for the United States, as the occupying power of Iraq in the immediate aftermath of the 2003 Iraq War, to use force against Iraqis who were attacking U.S. forces within Iraq. 

The second argument against Israel’s right of self-defense—that it cannot invoke this right against non-state actors like Hamas—is equally untenable. Article 51 of the UN Charter states that nothing shall “impair the inherent right” of self-defense possessed by all member states. In recent years, many governments, including the United States, have adopted the view that this right of self-defense applies against non-state actors like al-Qaeda and ISIS in situations where the government of the state in which the non-state actors are operating is “unwilling or unable” to prevent attacks by the non-state actor. The case of the Gaza conflict is much stronger for Israel than the “unwilling or unable” rationale; Israel is protecting against Hamas’ direct, indiscriminate killing, beheading, torture and hostage-taking of Israeli civilians. 

Of course, Israel must exercise its right of self-defense in conformity with international humanitarian law (IHL), also known as the laws of war or armed conflict. This body of customary international law, which was codified in the 1949 Geneva Conventions and their subsequent protocols, limits the use of force to the following situations: military necessity; where a distinction is made between combatants and non-combatants; and where the use of force is proportionate to the concrete military objective sought to be achieved. 

Israel Defense Forces' (IDF) attacks on Hamas military targets in Gaza, thus far, almost certainly comply with these principles. However, Hamas’ indiscriminate killings, beheadings, maimings, hostage-taking, and rocket attacks against Israeli civilians almost certainly violate these principles. Their violations extend to Gazans as well. Hamas places its military installations and fighters next to and underneath its civilian population centers, in the hope that the Israeli military response will result in collateral civilian deaths and produce battalions of additional supporters for the Palestinian cause. The weaponization of Gazan civilian lives is reprehensible, and we must keep in mind that it is an intentional, indeed central, strategy for Hamas. That strategy, whatever its harm to Israelis, is the direct cause of Gazan civilian deaths, injuries, and destruction of their property.

Hamas’ sympathetic observers—including apparently Columbia faculty members in their “Open Letter” of October 30 in defense of “robust debate” about the conflict—maintain that Gazans have “a right of armed resistance by an occupied people,” but also acknowledge that even “an occupied people must conform to the laws of war, which include a prohibition on the intentional targeting of civilians.” 

It is undisputed that Hamas launched its violent offensive against Israeli civilians before any use or threatened use of force against Hamas—indeed, at the time Israel was exploring with Hamas an arrangement to increase the number of Gazans allowed to work on the other side of the border. In this circumstance, Hamas has not claimed, and could not claim, any legitimate military necessity to justify its violence. 

Second, and importantly, there is no evidence that Hamas applied the principle of distinction in launching its strikes at Israeli targets. There is simply no evidence Hamas took steps to avoid attacking Israeli civilian targets with deadly force, even if they failed to kill all Israeli civilians in their sights. The failure to take such steps to avoid civilian targets is another clear violation of international humanitarian law (IHL). 

In contrast, the IDF publicly stated that its actions would adhere to the laws of armed conflict, and there is substantial evidence showing that it has thus far taken reasonable measures to comply with such laws. The IDF has stated it is targeting Hamas’ military capabilities that enable its atrocities and rocket attacks, which is a legitimate military purpose satisfying the principle of necessity. 

Secondly, IDF forces warned Gazan civilians of upcoming strikes via telephone and other electronic communications, used low-grade explosives to give occupants time to flee before heavier bombs arrived, and air-dropped leaflets warning civilians to evacuate before strikes occurred. Many fled to southern Gaza; others were barred or hindered by Hamas from doing so or were reluctant to pull up stakes. Such measures show that, at the very least, the IDF was reasonably attempting to fulfill the principle of distinction by avoiding civilian targets. 

Despite such measures, numerous civilians, mostly Palestinians, have died and will die in the Gazan conflict. Those civilian deaths are tragic and heartbreaking, but they are not necessarily evidence that Israel has failed to comply with IHL. Because Hamas’ military forces are often located in or in very close proximity to (indeed directly below) Gazan civilian areas—the use of civilian shields is itself a violation of IHL—legitimate attacks on those Hamas military targets will likely result in significant civilian deaths and injuries. 

The U.S. military’s use of drone strikes against al-Qaeda and ISIS also resulted in numerous civilian deaths despite the best efforts of the U.S. military to adhere to IHL. Indeed, requiring that Israel refrain entirely from attacks on Hamas military targets that are being actively used to launch attacks on Israeli civilian targets would render IHL unreasonably restrictive of a state’s use of military force to defend itself. The laws of war must allow states to act against legitimate military targets and to apply the principle of distinction in a reasonable manner, given the factual circumstances. 

This leads to the third legal principle: proportionality. While many critics of Israel will point to the relative death tolls as evidence that the Israeli attacks on Gaza are disproportionate, that claim misunderstands the concept. IHL requires militaries to use force proportional to the concrete military objective they are seeking to accomplish, not some proportionality between casualties on both sides. Without more facts, it is hard to judge whether each of Israel’s strikes fulfill this principle, but comparing the death tolls of Gazans and Israelis is the wrong way to resolve this legal question. 

Although steps should be taken to ensure that adequate food and medicine supplies get to Gazan civilians through the Rafah border crossing with Egypt, a cease-fire now with Hamas entrenched in its tunnels with armaments, tanks, explosives, drones, and hostages ensures continuation of Hamas butchery, not its cessation. 

The State of Israel was recognized by the UN General Assembly in 1947, the United States, and nearly all nations. The Jewish people’s right to “close settlement” was affirmed by the 1922 League of Nations Mandate for Palestine. They have had a continuous existence in Jerusalem, Safed, and other places going back to at least the Christian era. Their need for a state of their own was made abundantly clear during the Nazi period and unfortunately remains clear with each passing day. In the end the question boils down to whether Israel should be treated as a pariah state, a remnant instance of “settler colonialism” not entitled to the right of self-defense accorded all other nations yet warranting ongoing barbaric “armed resistance.” 

In defending the legality of Israel’s use of force in Gaza, I am not saying that the legality of Israel’s other policies affecting Palestinians or Israeli Arabs is beyond question. Some of those policies, such as expanding Israeli West Bank settlements, may be unwise and self-defeating. Nonetheless, opposing those policies cannot justify the indiscriminate use of force by Hamas against Israeli civilians. Nor can the objections to those policies limit Israel’s right to use military force to defend itself and to destroy and degrade Hamas’ military capabilities. 

Indeed, Israel’s basic legal framework and approach to using force is largely identical to that adopted by the U.S. military in its prosecution of the global war on terrorism against al-Qaeda and ISIS. Prominent critics of the legality of Israel’s actions in Gaza—whether in Congress, universities, or elsewhere—should keep these legal principles in mind before rashly accusing Israel of war crimes or condoning Hamas’ brazen violation of international humanitarian law. 

Samuel Estreicher is professor of law at NYU School of Law where he teaches, inter alia, Foreign Relations Law of the United States and has authored works on asymmetric warfare.

Image: Member of the Israeli Defense Force walking through Gaza. (X: Israeli War Room)