Proportionate Force?

Oversimplification is an easy and dangerous thing to do. (That sentence being a perfect example.) So, I'm not going to do that with the current Israeli-Hamas conflict going on in the Middle-East. But I'm confused by statements from the international community and UN representatives like the UN High Commissioner on Human Rights, among others, accusing Israel of the "disproportionate use of force" in its retaliation on Hamas's continuing rocket attacks. Nowhere have these experts on International Law and humanitarianism offered up what should be the obvious support for such an accusation: the appropriate proportionate force that Israel should be using against Hamas in Gaza.

The heavily left-leaning, Americans for Peace Now, asked this question in an interesting interview with Yossi Alpher:

Q. Is Israel employing disproportionate force?

A. I know of no way to counter terrorism with "proportionate" force. Should Israel fire rockets at Gazan civilians? Israel's use of massive force against aggression is legitimate under international law. It is more relevant to ask whether it will succeed.

It is far easier to accuse Israel of over-reacting than to suggest to Israel how it should have reacted.