Israel claims they have the right, in essence, to shoot through the civilians, because their enemy is hiding behind them. As hospitals and schools and UN shelters blow up, they say Hamas had assets in or near those places, and it is true often enough. Israel uses the best, most accurate weapons they possess to minimize civilian deaths, they say, and they regret the loss of innocent life, but Israel must defend itself. Israel has a right to exist.
I'm going to ignore the interesting question of whether Hamas represents an existential threat to Israel (if not, Israel is just taking its rage out on the helpless because they are helpless) and focus on the claim that it is permissible to kill civilians if you cannot strike your enemy without doing so.
Can't Hamas make a symmetrical claim? Can't they say their primitive rockets are one of a few, equally unsatisfactory ways they can strike their enemy? Surely they would prefer to do some damage to the IDF forces that surround and attack them, as opposed to, say, a cow, but it is difficult to do that with a weapon that can only be aimed at a compass point. Israel, I suppose, would object to giving Hamas better rockets, but wouldn't their claim that Hamas deliberately targets civilians scan better if Hamas had weapons that could target things?
(Human Rights Watch has declared that Hamas do target civilians. I am arguing that if it is wrong—or right—for one, it is wrong—or right—for both)
It is an inconvenient symmetry: If it is OK for Israel to kill Palestinian civilians because that is the only way they can strike their foe, then it is equally OK for Hamas to kill Israeli civilians for the same reason.
Of course, symmetry is symmetrical. If it is wrong for the Israelis to murder Palestinian civilians, then it is wrong for Hamas to murder Israeli civilians. The claims, in the first place, that billion dollar smart-weapons are insufficiently smart, and in the second that it's tough enough just to make a Qassam go north, excuse no one.
There is no symmetry of suffering; the slaughter is hideously lop-sided, against people who are not only helpless, but have already conceded everything that life permits. They have nothing more to give their tormentors than to die; to die in blood and fire and be cursed for being in the way; or to suffocate slowly, buried alive in Gaza and be forgotten. That Israel merely stop suffocating them is their desperate demand. It is a demand they have every right to make, since it is the demand for life itself, the same right to exist Israel invokes even as it exterminates them—not because it must: because it can.
And that demands a symmetry only The Hague can supply, though I doubt the world will find it convenient.