Israel has to respond 'disproportionately' to rockets on Sderot

In yesterday's Wall Street Journal, Bret Stephens did a brilliant job of showing why Israel's only real option in Gaza is a 'disproportionate' one (Hat Tip: Israpundit):The more vexing question, both morally and strategically, is what Israel ought to do about Gaza. The standard answer is that Israel's response to the Kassams ought to be "proportionate." What does that mean? Does the "proportion"