UKLFI has produced a short guide to what is meant by proportionality in the International Law of Armed Conflict.
Some people think that the principle of “proportionality” during armed conflict refers to the number of people which each side kills. So if Hamas murdered 20 Israeli civilians, Israel would be acting “disproportionately” if, in response, it killed more than 20 Palestinians. This is nonsense.
No state or combatant may militarily target any innocent civilians to achieve any objective, no matter how worthy and no matter how few or many it killed. This is precisely what Hamas does, not Israel.
The first obligation of any government is to protect its citizens. After the mass and indiscriminate slaughter on 7 October 2023 launched by a terrorist organisation from an adjacent territory, Israel is entitled, in self-defence, to enter that territory to dismantle that organisation to prevent it from ever repeating its murderous aims. This includes killing or capturing its members and destroying its capacity to manufacture, acquire or deploy weapons of war or destruction, its facilities, structures and buildings, wherever they may be found. That is Israel’s legitimate military objective.