Under Article 51 of the United Nations Charter, Israel has the right to defend its citizens against Gaza’s rockets. And in doing so, it isn’t bound by some one-to-one formula. It has the right to regard the threat that Hamas poses as an annihilating one, given the emphatic language of its Covenant. Yet because it is a liberal democracy guided by enlightened, humanistic values, which come into conflict whenever it is forced to defend itself against those for whom martyred lives are badges of religious honor, laws only offer limited guidance.

Israel’s moral dilemma is also untenably compounded by the asymmetry of its and Hamas’ campaigns on the ground. Hamas’ fighters, and their stockpile of weapons, are embedded among civilians—and targeting civilians and casually living among them violates the rules of war. Wholly unique to most armies, Israeli soldiers almost never confront a combatant in uniform. The hell that is war is magnified by the morbid knowledge that every weapon fired might kill an actual civilian, an innocent child, a pregnant woman. Generals of long ago rarely faced such foes or fought with such regret.