From Robert Kaplan:
How do you fight unconventional, sub-state armies empowered by ideas? You undermine them subtly over time, or you crush them utterly, brutally. Israel, unable to tolerate continued rocket attacks on its people, has decided on the latter course. Our own diplomacy with Iran now rests on whether or not Israel succeeds. We need to create leverage before we can negotiate with the clerical regime, and that leverage can only come from an Israeli moral victory—one that leaves Hamas sufficiently reeling to scare even the pro-Iranian Syrians from coming to its aid. In defense of its own territorial integrity, Israel has, in effect, launched the war on the Iranian empire that President George W. Bush and Vice President Dick Cheney, in particular, can only have contemplated.
This war really started two and a half years ago, in Lebanon, and Israel has been fighting it mostly on its own, but as he points out, the US has to be ready to continue the pressure on Tehran if/when Israel crushes its puppet in Gaza.