Israel, Hamas, and the laws of war

European leaders agree that Israel has the right to defend itself as long as it complies with international law. It is time that they recognise the limits those laws set

Israeli soldiers manoeuver armored military vehicles along Israel’s border with the Gaza Strip, in southern Israel, on Monday, Nov. 20, 2023. The Israeli military has deployed hundreds of thousands of troops in and around Gaza as it conducts a ground offensive against Hamas militants inside the territory. (AP Photo/Ohad Zwigenberg)
Israeli soldiers manoeuver armored military vehicles along Israel’s border with the Gaza Strip, in southern Israel, on Monday, Nov. 20, 2023.
Image by picture alliance / ASSOCIATED PRESS | Ohad Zwigenberg

In the weeks since Israel launched its ferocious military campaign against Hamas in Gaza following the armed group’s attack on Israel on 7 October, European leaders have repeated a simple formula about the limits that Israel should observe. While they have disagreed about whether to call for a ceasefire or pause to the fighting, they have all agreed that Israel has the right to defend itself in line with international law and international humanitarian law.

Europe’s continuing statements of this position ring increasingly hollow as the human toll of Israel’s campaign mounts. By mid-November, more than 12,000 Palestinians had been killed in Gaza, of whom nearly 70 per cent are women and children. At the time of writing, Israel is focusing its military operations on Gaza’s hospitals – where medical care is already stretched to its limits by shortages of power, food, and clean water.

European leaders have largely refrained from publicly questioning whether Israel is violating international law. They have expressed concern about the impact on civilians and some, including France’s president Emmanuel Macron, have said that too many people are being killed. Belgian officials have gone further and questioned whether Israel is following the laws of war. But in the absence of any explicit suggestion that Israel is breaking international law, Europe’s overall endorsement of Israel’s operation stands. As the military campaign enters a new phase that may involve operations in Gaza’s now densely crowded south and raises increasing questions about how the operation will end, it is time for European leaders to speak more clearly about what international law requires.

Laws on the conduct of hostilities

The body of law that has been most discussed in media coverage of the war in Gaza is the laws of war or international humanitarian law (IHL), which regulates what fighters are allowed to do during conflict. Serious violations of IHL are classed as war crimes. A large part of IHL is designed to limit the harm to civilians of military operations. The law recognises that wars cannot normally be fought without civilians being killed and injured, but aims to strike a balance between the measures that a party to any conflict needs to take to prevail and the constraints that it must observe to prevent excessive harm to those not involved in fighting.

IHL includes some absolute prohibitions. Attacks cannot target civilians at any time unless they are taking part in hostilities. Civilian infrastructure cannot be deliberately targeted unless it is being used for military purposes, for example to launch attacks or store weapons. Medical facilities have special protection and cannot be attacked unless they are being used to commit acts harmful to the enemy, and then only after a warning. Collective punishment (acts directed against a large population in retaliation for actions of some of its individuals) and attacks that make no attempt to distinguish between military and civilian targets are always prohibited. Torture, rape, starvation, and the taking of hostages are forbidden.

Beyond that, IHL includes a series of rules that limit permissible civilian casualties even when attacks are directed at military targets. The principle of proportionality forbids attacks when their likely incidental harm to civilians is excessive in relation to the concrete and direct military advantage anticipated. The rule of precautions in attack requires that armed forces do everything feasible to minimise civilian casualties, including choosing the attack option that is likely to cause least incidental harm to civilians. Finally, leaders and commanders are obliged to respect and ensure respect for IHL in all circumstances.

Many of Hamas’s acts against Israel on 7 October were violations of these rules and war crimes. In the case of many of Israel’s actions, the rules of IHL make it necessary to look at their context and motivation to reach a clear judgment. Nevertheless, a review of the evidence strongly suggests that Israel has violated IHL and committed war crimes.

Israeli forces blocked all supplies, including food, water, medicines, and electricity from entering Gaza for several days after Hamas’s attack, with the defence minister Yoav Gallant saying Israel was “putting a complete siege” on the territory, and has since continued to restrict supplies. Israel has also reportedly attacked water towers, electricity generating stations, and fishing boats, further limiting the food and water available for Gaza’s residents. Since it is hard to see any motive for these actions other than striking back against Gaza’s inhabitants, this seems like a clear case of collective punishment. Aid groups have said the population of Gaza is suffering a life-threatening shortage of food, suggesting that Israel may be guilty of the crime of starvation. IHL also calls for humanitarian relief supplies to be allowed when the civilian population is suffering undue hardship due to the lack of supplies essential for its survival; Israeli restrictions on aid are a violation of this rule.

Proportionality and precautions in attack

Israel has repeatedly attacked residential buildings and neighbourhoods in Gaza, and some experts and NGOs have accused it of carrying out indiscriminate attacks. Israel says all its attacks have been aimed at facilities that are being used by Hamas for military purposes, and that Hamas routinely places its command centres, staging grounds, and weapons stores in apartment buildings, hospitals, and mosques. Even so, Israel must observe the rule of proportionality. The level of civilian death and harm that is excessive in any particular case is hard to define with precision and depends on the military importance of the target. Nevertheless, the proportionality rule sets an objective limit on civilian death, sometimes framed as what a reasonable commander would have thought permissible when considering whether an attack should go ahead. Attacks that cause disproportionate civilian harm are a war crime.

To take only one example, it is hard to see how Israel’s strikes on the Jabalia refugee camp, which killed at least 195 people according to Gazan authorities and apparently killed two Hamas officers and a number of other fighters, meet this threshold. They appear disproportionate according to the standards used in the limited case law on proportionality from international tribunals. According to experts who have studied the targeting practices of different military forces, Israeli attacks have caused a level of civilian death that is much higher than US or UK forces have permitted in counterinsurgency warfare.

The obligation to take precautions to avoid killing or wounding civilians is also context-dependent, since it only requires states to do what is feasible in the circumstances. Israel claims that telling the population of northern Gaza to move to the southern part of the territory was an attempt to reduce civilian casualties, though the move imposed a drastic burden on resources in the south and there was no initial effort to allow civilians to move safely. In any case, this warning does not lift the obligation to do everything feasible to protect the civilians who remain. It is clear that Israel is conducting this war at an exceptional level of intensity even by the standards of urban conflict. According to the UN agency UNRWA, 17 Israeli attacks on schools housing refugees have killed 176 people, despite Israeli forces being notified of their location, showing an evident lack of concern about civilian harm. US officials have pressed Israel to adopt a series of specific measures to minimise civilian casualties, including gathering more intelligence before launching strikes and using smaller bombs in crowded areas.

There are also reasons to think that Israel’s attacks on medical facilities have not respected their special protections under IHL. Israel’s attack on an ambulance convoy outside al-Shifa hospital, which killed 15 people and wounded many more, appears to have been based on imprecise intelligence and not to have followed any warning, as the rules on medical facilities require. The World Health Organization has recorded over 137 attacks on healthcare facilities in Gaza since 7 October, resulting in 521 deaths including 16 health workers on duty. General statements that Hamas uses medical facilities and ambulances for military purposes do not make this lawful – there must be clear evidence in every case. As the campaign moves towards further military operations in hospitals, it is essential that Israel does not attack unless it has established that they are being used to commit harmful acts and that everything possible is done to allow medical treatment to continue.

General statements that Hamas uses medical facilities and ambulances for military purposes do not make this lawful – there must be clear evidence in every case

A lot of the questions surrounding the legality of Israeli actions involve judgment calls that consider the circumstances surrounding each attack – but that doesn’t mean that judgments can’t be made. While a full independent investigation is needed to clarify the details about each incident, European officials who have invoked international law should say clearly that they do not believe these rules are being followed. They should also question the rhetoric used by senior Israeli officials, which has often erased the distinction between civilians and Hamas fighters and thus flouts their obligation to ensure respect for the law. The degree to which armed forces follow the laws of war in the heat of battle depends greatly on whether they are encouraged by superiors to do so, but rather than reminding Israeli troops of the importance of protecting Palestinian civilians, Israeli leaders have used language that dehumanises or implicates them in Hamas’s crimes.

The meaning of self-defence

If Israel complied fully with IHL in its Gaza campaign, it would reduce the number of civilians killed by its attacks. But IHL can only do so much. It is a fundamentally pragmatic body of law that accepts the realities of warfare – and the import of its rules is often disputed between scholars who respectively emphasise military necessity and humanitarian concerns. Most importantly, IHL looks only at the conduct of hostilities and not at whether and how far each side’s overall use of force is justified. In the case of Gaza, there is a further set of legal questions about the broad scope of Israel’s military campaign, in particular whether the right of self-defence permits Israel to extend its campaign as far as it apparently intends to, with all the destruction that will necessarily involve.

There are some legal complications about how the law on the use of force, which regulates questions of self-defence, applies to Israel’s attack on Hamas. That law is principally expressed in the United Nations Charter, which deals with the use of force by one state against another. In Gaza, where Israel is confronting an armed group in a territory whose status is disputed, it is debatable whether the UN Charter prohibition applies. Nevertheless, it seems reasonable to believe that the international rule of law requires that any state’s use of force, even against members of a non-state armed group, must be limited to what is justified in light of the threat it faces. Presumably European countries that say Israel has a right to defend itself mean that Israel should only use the degree of force that self-defence requires.

Generally the right of self-defence is understood to be limited to actions that are necessary and proportionate to the threat posed by an armed attack. A state that has been attacked can only use the degree of force that is necessary to respond to the armed attack and only as far as the measures taken are proportionate to the threat posed by the attack. This is a separate proportionality test to the one in IHL, which only applies to individual attacks. While some scholars argue that the right of self-defence must be limited to repelling an ongoing attack or preventing an imminent one, others believe that it also allows the victim state to reduce the attacker’s capacity to mount further such attacks and deter it from doing so. In any case, retribution for a completed attack is not a legitimate reason for the use of force in self-defence.

Assessing Israel’s goals

Israeli prime minister Benyamin Netanyahu says the objective of the military operation in Gaza is “to destroy Hamas’s governing and military capabilities” as well as to bring the hostages home. European states need to ask themselves whether this goal is truly necessary in light of the threat posed by Hamas and, if so, whether the destruction involved in achieving it outweighs the benefit that Israel would gain. The legal scholar Adil Ahmad Haque has argued that the imbalance between the harm that Israel’s campaign will cause and the harm to Israel that it will prevent is “so lopsided that it cannot plausibly be considered proportionate”.  Norwegian prime minister Jonas Gahr Støre said that Norway supported Israel’s right of self-defence but required that proportionality be respected, and that “the extent of destruction and the humanitarian suffering happening now is beyond that.”

Most European countries would agree that Israel’s self-defence involves degrading Hamas’s military capabilities. But the goal of destroying the group’s military and governing capabilities goes far beyond that – and it is unclear where exactly it would stop. Hamas is deeply embedded in Gaza’s society. A former senior Israeli military lawyer has argued that destroying Hamas will involve destroying Gaza. Moreover, it is hard to avoid the suspicion that Israel’s actions are not just directed at Hamas but also at persuading Israel’s enemies across the region that it will strike back with extreme force to any attack. This objective cannot be encompassed within the right of self-defence against Hamas. Finally, it risks being self-defeating, since an extreme Israeli campaign is most likely to drag other groups like Hezbollah into the fight.  

So far, European countries’ invocation of the formula that Israel can defend itself in line with international law has not served as a meaningful tool to constrain Israel’s actions. The failure to consider how far Israel’s campaign can lawfully extend is complicating attempts to bring an end to the fighting – as some European countries are reluctant to call for a ceasefire as they think Israel should be allowed to take further action against Hamas. To make their commitment to international law meaningful and protect civilian lives in Gaza, European leaders need to take a clearer line on the constraints that law imposes on Israel’s conduct of hostilities and the limits to its right of self-defence.

The European Council on Foreign Relations does not take collective positions. ECFR publications only represent the views of their individual authors.


Senior Policy Fellow

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