Israel's Ambassador to the United States Ron Dermer on proprtionality:

"It's important to understand what proportionality is in terms of the rules of war. There's two basic principles that you have to remember. The first is distinction, you make a distinction between combatants and noncombatants. That's the most important principle of the rules of war, that you have to make that distinction. And here Israel always makes that distinction. You have have Hamas that is deliberately targeting our civilians hoping to kill as many as possible. And you have Israel that does not deliberately target a single Palestinian civilian. We don't deliberately target their civilians. For us, when a civilian is killed it's an operational failure. And the more civilians who are killed, the greater the operational failure. And obviously a tragedy even of itself. And for Hamas, they celebrate—the greater the number of civilian casualties, for them, the greater the success of their operation.

    And then you have the issue of proportionality.

    Let's say there's a legitimate target because when a schoolhouse, hospital, mosque is turned into a military command center or a weapons depot, or a place where you fire rockets, it becomes by the rules of war a legitimate target. You cannot turn a hospital into a military command center. You cannot do that according to the rules of law. It's a war crime for Hamas to do that. You cannot turn an UNRWA school into a weapons depot, that's a war crime. You cannot use a Mosque as a missile manufacturing facility. It becomes a legitimate target. Then the question is okay, but can you target it in this specific instance.

    There you get into the question of proportionality. Meaning, just because it's a legitimate target doesn't necessarily give you the right to hit it. Because for that, for you to be able to do that, you have to show that the gain you will get from the military action you take is worth the potential loss of lives that you might even foresee ahead of time. So I don't want to get into theoretical examples but if you had you know 1 rocket that was sitting in a school somewhere and there are 50 kids in a classroom, then you cannot actually target to get to that rocket and kill those kids. That would be disproportionate because the gain that you have by hitting that one rocket would not justify killing 50 kids in the school. By the same token if you had 200 rockets in place and you had one civilian, by the rules of war, you could target that place even if you knew ahead of time that the civilian would be hurt.

    Now there are all sorts of judgment calls that happen in between. Can you target that same target tomorrow or in an hour or in three hours? And Israel is always making these calculations."