The next Middle East war -- Israel against genocidal Islamism -- has begun. The first stage of the war started two weeks ago, with the Israeli incursion into Gaza in response to the kidnapping of an Israeli soldier and the ongoing shelling of Israeli towns and kibbutzim; now, with Hezbollah's latest attack, the war has spread to southern Lebanon. Ultimately, though, Israel's antagonists won't be Hamas and Hezbollah but their patrons, Iran and Syria. The war will go on for months, perhaps several years. There may be lulls in the fighting, perhaps even temporary agreements and prisoner exchanges. But those periods of calm will be mere respites.

The goals of the war should be the destruction of the Hamas regime and the dismantling of the Hezbollah infrastructure in southern Lebanon. Israel cannot coexist with Iranian proxies pressing in on its borders. In particular, allowing Hamas to remain in power--and to run the Palestinian educational system--will mean the end of hopes for Arab-Israeli reconciliation not only in this generation but in the next one too.

For the Israeli right, this is the moment of "We told you so." The fact that the kidnappings and missile attacks have come from southern Lebanon and Gaza -- precisely the areas from which Israel has unilaterally withdrawn--is proof, for right-wingers, of the bankruptcy of unilateralism. Yet the right has always misunderstood the meaning of unilateral withdrawal. Those of us who have supported unilateralism didn't expect a quiet border in return for our withdrawal but simply the creation of a border from which we could more vigorously defend ourselves, with greater domestic consensus and international understanding. The anticipated outcome, then, wasn't an illusory peace but a more effective way to fight the war. The question wasn't whether Hamas or Hezbollah would forswear aggression but whether Israel would act with appropriate vigor to their continued aggression.

It wasn't the rocket attacks that were a blow to the unilateralist camp, but rather Israel's tepid responses to those attacks.

So it wasn't the rocket attacks that were a blow to the unilateralist camp, but rather Israel's tepid responses to those attacks. If unilateralists made a mistake, it was in believing our political leaders -- including Ariel Sharon and Ehud Olmert -- when they promised a policy of zero tolerance against any attacks emanating from Gaza after Israel's withdrawal. That policy was not implemented -- until two weeks ago. Now, belatedly, the Olmert government is trying to regain something of its lost credibility, and that is the real meaning of this initial phase of the war, both in Gaza and in Lebanon.

Still, many in Israel believe that, even now, the government is acting with excessive restraint. One centrist friend of mine, an Olmert voter, said to me, "If we had assassinated [Hamas leader] Haniyeh after the first kidnapping, [Hezbollah leader] Nasrallah would have thought twice about ordering another kidnapping." Israel, then, isn't paying for the failure of unilateral withdrawal, but for the failure to fulfill its promise to seriously respond to provocations after withdrawal.

Absurdly, despite Israel's withdrawal to the international borders with Lebanon and Gaza, much of the international community still sees the kidnapping of Israeli soldiers as a legitimate act of war: Just as Israel holds Palestinian and Lebanese prisoners, so Hamas and Hezbollah now hold Israeli prisoners. One difference, though, is that inmates in Israeli jails receive visits from family and Red Cross representatives, while Israeli prisoners in Gaza and Lebanon disappear into oblivion. Like Israeli pilot Ron Arad, who was captured by Hezbollah 20 years ago, then sold to Iran, and whose fate has never been determined. That is one reason why Israelis are so maddened by the kidnapping of their soldiers.

Another reason is the nature of the crimes committed by the prisoners whose release is being demanded by Hezbollah and Hamas. One of them is Samir Kuntar, a PLO terrorist who in 1979 broke into an apartment in the northern Israeli town of Nahariya, took a father and child hostage, and smashed the child's head against a rock. In the Palestinian Authority, Kuntar is considered a hero, a role model for Palestinian children.

The ultimate threat, though, isn't Hezbollah or Hamas but Iran. And as Iran draws closer to nuclear capability -- which the Israeli intelligence community believes could happen this year -- an Israeli-Iranian showdown becomes increasingly likely. According to a very senior military source with whom I've spoken, Israel is still hoping that an international effort will stop a nuclear Iran; if that fails, then Israel is hoping for an American attack. But if the Bush administration is too weakened to take on Iran, then, as a last resort, Israel will have to act unilaterally. And, added the source, Israel has the operational capability to do so.

For Israelis, that is the worst scenario of all. Except, of course, the scenario of nuclear weapons in the hands of the patron state of Hezbollah and Hamas.

The opinions expressed here are those of the author.

This article originally appeared in the New Republic.