Target: Hezbollah: it may well make sense for Israel, and for an endangered world.

IRAN, as its president Mahmoud Ahmadinejad said in his recent letter to George W. Bush, is hearing the sounds of "the shattering and fall of the ideology and thoughts of the liberal democratic systems." That is a general threat to the international order. With astonishing and obsessive regularity, Ahmadinejad rehearses a particular promise to wipe out Israel. According to most experts, Iran will complete its nuclear program within a period of one to three years, four at most. The regime asserts that this program is solely for peaceful purposes, but it is flagrantly breaking the nuclear-nonproliferation rules. Suspicion and fear of its intentions are further justified by the terror and deceit it has practiced since 1979, the year of Iran's Islamic revolution.

A Third World pre-industrialized country, Iran should in reality be a regional power at best, but evidently Ahmadinejad sees himself mobilizing Muslims everywhere--not just fellow Shiites, but Sunnis as well--for a clash of civilizations that he is sure to win, with God on his side. His belligerence appears to be actively inviting attack from liberal democracies --and first of all Israel--because this will certify his Islamism. The irrational element in the credo is what links him and the ruling ayatollahs to Hitler and Stalin, secular though those two were.

One possible response is to wait and see what happens next, as the Western democracies by and large did in the 1930s. Now as then, fatalism settles in, dictating that Iran will soon go nuclear and nothing can be done about it. The recent British foreign minister, Jack Straw, for instance, gave his hand away when he went on record to say that any use of force would be "inconceivable." To give an impression of activity, fatalist politicians and commentators advocate "engagement," a euphemism for keeping up appearances while doing as little as possible. Time and again Tehran enters a process of talks, only in order to stall and pursue its program regardless. But according to the fatalists, the ayatollahs aren't really irrational or ideological: They will prove responsible once they have in their hands this accretion of power; Mutual Assured Destruction will surely curtail their messianic mission, as it did the Kremlin's.

President Bush's doctrine of preemption offers the obvious alternative that the day is coming when the Iranian nuclear program will have to be taken out by whatever means are available. But the fatalists quickly counter that any use of force will hurt us as much as them. Muslim rage and nationalist backlash will make the clash of civilizations a fact of life. Terrorism will become unstoppable, and who knows what nasty surprises may be in store? The Iranians will close the Strait of Hormuz, and interrupt oil supplies with incalculable consequences.

Caught in the cross-currents of fear and wishful thinking, Tehran, Washington, and London seem to be creating almost ideal conditions for misunderstandings and miscalculations.

The Cold War offers the successful precedent of containment, a compromise between surrender and force, one of those much-vaunted Third Ways. This involves the usual gamut of measures available for treating rogue states: sanctions, boycotts, exclusion from the World Cup, motions in the Security Council, and whatever else diplomats and lawyers can devise. Given its increasing resentment over the outcome of the Cold War, Russia has broken ranks, selling Iran advanced missile weaponry; and some 2,500 Russian technical experts are at work on the nuclear program. Also unfortunately, the U.N. commission whose purpose is nuclear disarmament has just negated itself by electing an Iranian member. Nevertheless, the majority of Iranian clerics are corrupt, and a substantial part of the population is wholly contemptuous of them and the barbaric society they have put in place. Conceivably, a more unanimous international pressure could intensify internal dissatisfaction to a degree that the regime might not be able to repress, ruthlessly totalitarian though it is. In which case, the regime might dissolve as once the Soviets did.

Facts on the ground, however, are likely soon to be overtaking fatalists and containment-hopefuls alike. For years Iran has been building a position of strength in Lebanon by recruiting, arming, and financing Hezbollah, in effect colonizing the country by stealth. Under the command of Iranian clerics, Hezbollah is at once a militia of about 8,000 gunmen, a political party, and a state within the state. Unlike other Lebanese militias, it refuses to disarm. Its arsenal includes some 10,000 Katyusha rockets capable of doing damage deep into Israel. Unless or until Iran develops the nuclear bomb and the means to deliver it, Hezbollah remains its one immediately effective weapon against Israel. Senior Iranians stir the pot with announcements that, should the United States "make any mischief" in Iran, "the first place we will target will be Israel."

Real mischief is currently building in the Gaza Strip and the West Bank. The Islamists of Hamas won the recent election, but the secular nationalists of Fatah are unwilling to concede that they lost it. Nominally the Palestinian president but more essentially leader of Fatah, Mahmoud Abbas is refusing to allow Hamas control of the security forces. The Hamas foreign minister is accusing Abbas of "paralyzing" the government. In this standoff, and in the absence of either law or order, the two sides have begun to shoot it out. "The anarchy in the Gaza Strip will lead to a civil war," the foreign ministers of Egypt, Jordan, and Saudi Arabia declared at a meeting in Cairo. They know what they are saying.

And so does the Hezbollah leader, Sheikh Hassan Nasrallah, a black-turbaned cleric who alternates in the usual Iranian Islamist style between anger and self-pity. He chose the same moment to break out of the conspiratorial secrecy in which Hezbollah operates and admit that it is giving "financial, political, and military support" to Palestinian organizations, namely Hamas and Islamic Jihad.

In November last year, Hezbollah launched a heavy attack along the entire Lebanese border with Israel while attempting to abduct Israeli soldiers. Once retired, Israeli generals and intelligence chiefs are free to speak their mind, and a number of such personalities have been warning about the rising danger from Hezbollah. Last year, one former intelligence chief says, as many as 4,000 would-be terrorists were thwarted; and another foresees a "tsunami" of terror this year. At some point, such a level of violence breaks its bounds and becomes a threat to national life.

So long as the Palestinians engage in a power struggle between themselves, Israel can afford to be a bystander and possible beneficiary. But outside interference of any kind is a very different matter. Iran has found a way to make mischief through its satellites and proxies in Iraq, while piously disclaiming responsibility. Through Hezbollah, it is poised to use the same tactic against Israel.

It is notoriously unwise to make predictions, especially concerning the Middle East in its current instability, but it seems all too probable that Iran will find it irresistible to up the stakes by this trick of using proxies, and in that case dare the Israelis to attack. Iran needs to push Israel to extremes if it is to claim ideological justification for dropping the nuclear bomb someday in the near future in final retaliation.

Israel has to weigh which is the worse choice: either fatalistically to do nothing in the face of ever-mounting provocation, or to accept the challenge and respond to it with enough strength to knock Hezbollah out of the ring in southern Lebanon. An invasion would in effect restore the occupied zone carved out after the 1982 campaign to destroy Fatah, and show that evacuation of the area in 2000 had been a mistake. Walid Jumblatt is one of the wiliest of Lebanese politicians, and when he says that Hezbollah should disarm now, and goes on to ask why Lebanon alone should be an arena for Arab-Israeli conflict, he may well be reading the omens correctly.

Israel has never been inclined to participate in its own extinction. The elimination from the equation of Hezbollah and those 10,000 Katyusha rockets would relieve a present danger, and serve to contain Iran by proving the limits of its reach; and it might also extend the strange Phony War through which the world is now living until such time as the Iranians are able to save themselves from their doom-laden regime.

Mr. Pryce-Jones is an NR senior editor. His latest book is Betrayal: France, the Arabs, and the Jews, forthcoming from Encounter.