This accusation reflects a distortion of the concept of proportionality in International Humanitarian Law (IHL). As military law expert Prof. Geoffrey Corn has explained, the principle of proportionality applies in two contexts – Israel’s legal right to use force (jus ad bellum) and its mitigation of the incidental risk to civilians when attacking lawful targets (jus in bello).[1]

Proportionality I – Israel’s legal right to use force

Israel’s legal right to use force is based on the UN Charter and customary international law.[2] Article 51 of the UN Charter provides that member states are entitled to exercise their “inherent right of…self-defense” in a response to an “armed attack.” This includes attacks by non-state actors like Hamas.[3] On May 10, 2021, Hamas launched an unprovoked military attack on Israel, firing seven rockets at Jerusalem. Hamas had no legal authority for the attack.[4] During the next 11 days the terrorist organization fired over 4,000 rockets targeting Israeli civilians, killing 13, injuring 300, terrorizing millions and causing millions of dollars in damage.

Therefore, as the party attacked, Israel had the right to do what was necessary to restore its safety, including using force “reasonably necessary to discourage future armed attacks.”[5] In the words of Prof. Geoffrey Corn:

Proportionality in that context means that Israel has to make a reasonable judgment that the scope of its operation – the totality of the operation – is genuinely necessary to reduce the nature of the threat it’s facing…The law doesn’t require a “tit-for-tat” response. You first assess what the gravity of the threat is, and then assess what you need to do to reduce that threat. That’s what we call ad bellum proportionality, or the “legal right to use force” proportionality.[6]

Western governments overwhelmingly supported Israel’s right to self-defense.[7]

Proportionality II – Israel’s mitigation of incidental risk to civilians

The above accusations most likely relate to the second type of proportionality, i.e., the obligation to mitigate harm to civilians. While the knee-jerk reaction, as reflected in these accusations by North Korea, South Africa and Vietnam, is to accuse Israel of “disproportionate” attacks by looking at the effects of the conflict (i.e., the number of dead on each side), this mischaracterizes the IHL proportionality rule.

An attack is disproportionate only if the “expected civilian casualties will be excessive in relation to the anticipated military advantage gained.”[8] As military law expert Prof. Laurie Blank has explained, this is a prospective analysis of what a reasonable commander would have decided based on the information available at the time. It is not an “effects-based” test that looks at casualty numbers after the fact. Moreover, IHL accepts the lawfulness of some incidental civilian casualties.[9]

Furthermore, the proportionality determination cannot be made without access to the real-time information on which the military commanders based their decision. As explained by military law expert Prof. Geoffrey Corn:

“unless you know what the target was, and the value that the commander assessed in destroying that target, you don’t know if it’s illegal…you need to know the full equation – you need to know why the commander was attacking, why he used that weapon, and why he did it at that time, in order to make an assessment of whether the proportionality judgment was credible.”[10]

During this conflict, Israel took many concrete steps to minimize civilian harm, including (1) choosing an aerial campaign rather than a ground invasion, and using extremely precise missiles capable of taking out a military target in the middle of a civilian area with minimal collateral damage; (2) providing advanced warnings (phone calls, text messages, roof-knocking,[11] etc.) to civilians in or near the target giving them sufficient time to evacuate—a tactic documented by, among others, former-UNRWA Gaza head Mathias Schmale[12] and the Al Jalaa media building owner;[13] and (3) aborting strikes when civilians were detected in the vicinity, as reflected in a voice recording of IDF command control calling off a strikes at the last minute when children were detected nearby.[14]

Military law experts have praised Israel’s advance warning system, emphasizing that it goes beyond what the law requires and sets a high threshold that other nations may not be able to match. For example, Prof. Michael Schmitt said “The IDF’s warnings certainly go beyond what the law requires, but they also sometimes go beyond what would be operational good sense elsewhere.” He also expressed concern that people might “start thinking that the United States and other Western democracies should follow the same examples in different types of conflict. That’s a real risk.”[15] Similarly Col. Richard Kemp noted: “we can’t call everyone in Iraq before a strike.”[16]

The fact that there were fewer deaths on the Israeli side reflects the reality that Israel expends enormous resources to protect its civilians through its iron dome missile defense system and by ensuring bomb shelters are constructed and accessible. In contrast, Hamas diverts international aid money meant to improve Gazan lives for its terrorist infrastructure and purposely operates from inside civilian areas placing its civilian population and infrastructure at risk—effectively using them as human shields.