If Israel were now to withdraw under pressure without accomplishing the objectives of severely weakening Hamas and preventing the reconstitution of a terror-exporting state in Gaza, it would be a triumph for Iran. In either case, the Iranian regime would be emboldened, and less susceptible to the pressure from the Obama administration to stop its nuclear program. But a defeat of Hamas in Gaza — following on the heels of our success in Iraq — would be a real setback for Iran. It would make it easier to assemble regional and international coalitions to pressure Iran. It might positively affect the Iranian elections in June. It might make the Iranian regime more amenable to dealing. With respect to Iran, Obama may well face — as the Israeli government did with Hamas — a moment when the use of force seems to be the only responsible option. But Israel’s willingness to fight makes it more possible that the United States may not have to.