ISRAEL, OBSESSED with the prospect of nuclear weapons in the hands of the Iranian leadership, may inadvertently destroy itself-that is, cease to exist as a coherent Jewish state-without a single shot being fired or bomb blowing up. In particular, overwrought and underexamined fears that Iran simply might obtain a bomb could lead to substantial Jewish emigration from Israel. When this is coupled with the potentially disastrous consequences of an Israeli attack on Iran, there is a danger that Israel's future could be imperiled.

In spite of its remarkable successes, Israel faces several key hurdles. It is surrounded by countries filled with hostile people, some of whom continue to present a persistent terrorism threat; it has followed a program, almost universally considered illegal, of erecting settlements in occupied territories and seems incapable of reversing this process; it is confronted by an ominous demographic dilemma in which Jews, already a minority between the Jordan River and the Mediterranean Sea, may eventually become an uncomfortably narrow majority within Israel proper, a dilemma that in turn is creating heavy pressures to protect Jewish control of the government by sacrificing democracy; prospects for any kind of negotiated peace are diminishing; and the country faces pariah status in the international community. It is against this backdrop that Israel confronts the prospect of a potentially nuclear-armed Iran.

Judicious and balanced concerns about that danger are, of course, justified. But rather than confronting that prospect with sober assessment, Israelis view it as an existential threat akin to the Holocaust. Israeli reactions to the possibility of a nuclear-capable Iran have been dominated by panic and even despair, and by loss of hope for the future. Israeli politicians and commentators from the political left as well as right persistently draw analogies with the 1930s and Hitler's Germany. The influential Israeli historian, Benny Morris, warns of the "danger of extinction in the short term from an Iranian nuclear bomb." As Yossi Klein Halevi and Michael Oren noted in a New Republic article last year, apocalyptic thinking abounds in the Israeli defense establishment and "military men suddenly sound like theologians when explaining the Iranian threat." Some inside Israel spookily point out that according to the ravings of Iranian President Mahmoud Ahmadinejad, the Shia savior, the Hidden Imam, will return in 2009 to defeat evil once and for all-the same year Israel believes Iran will obtain a nuclear weapon. In private conversations with Israeli leaders, the link between this kind of thinking and the psychological threats to Israel's future is made clear. As one former Likud minister told one of the authors recently, it is not the idea that Iran will actually use nuclear weapons against Israel that is terrifying. Instead, the real problem is the prospect that Israeli Jews will be unable to tolerate images of the destruction that could be wrought in some undefined future by an Iranian atomic capability.

The existential danger for Israel in all this arises not so much from Iran's capacity or potential capacity to do harm. It comes rather from the consequences of Israeli fears and Israeli hype, at once apoplectic and apocalyptic.

CREATING THIS climate of fear leads to two problems that could imperil or even destroy the Israeli state: demoralizing levels of emigration and a potentially futile, or even spectacularly counterproductive, attack on Iran.

There is a real danger that increasing numbers of Israeli Jews, at least those with the skills and wherewithal to do so, may leave the country. After all, Israelis are being bombarded with claims that a nuclear Iran is the death knell for their country and that a nuclear Iran is possible-even inevitable. In response to this government-generated hysteria, the conclusion that the state is effectively doomed may be difficult to avoid, as is the conclusion that it might be better to live elsewhere-in a place where one can raise children free from fear of a nuclear holocaust.

Is the idea of Jews leaving the country in politically significant numbers farfetched? Hardly. The return to the ancient homeland is one of the great sagas of the modern era; certainly an exhilarating event for most Jews. But with annual emigration from Israel rising and often exceeding immigration, it is worth remembering that historically Jews have left the promised land just as often as they have returned to it. And, indeed, so far in the twenty-first century more have left than have arrived.

Moreover, a recent survey indicates that only 69 percent of Jewish Israelis say they want to stay in the country, and a 2007 poll finds that one-quarter of Israelis are considering leaving, including almost half of all young people. In another survey, 44 percent of Israelis say they would be ready to leave if they could find a better standard of living elsewhere. Over one hundred thousand Israelis have acquired European passports as "insurance" in recent years, and there have been passionate discussions about a "brain drain" problem-emigration of talented Israelis, especially university professors.

The overwhelming psychological and mythic power of the Holocaust for Israelis is clear. But the fear and alarm that result do not necessarily lead to wise policy. Collective memory may account for the solidarity and courage Israelis have readily and regularly displayed, but it may also help Ahmadinejad use Iran's ambiguous, but apparently vigorous, attempt to become a nuclear power to provoke panic and overreaction.

The process of ratcheting up the level of fear has required Israelis to insist that Iran will imminently develop an atomic weapon, and that its leadership is so deranged and suicidal that it will actually use the weapon on Israel despite Israel's ability to massively retaliate-not to mention the capacity of its ardent backer, the United States, to react in a similar manner. And once the threat is characterized as such, there is no limit to the measures Israelis can imagine would be justifiable in response.

WHEN SURVIVAL is perceived to be at stake, there is neither need nor rationale for thinking about consequences, about how to calibrate the use of force to foster positive outcomes or reduce the political fallout of military action. And so Israel may well attack Iran in an attempt to stymie Tehran's nascent nuclear capabilities, no matter how risky or how destructive to future peace in the region an attack might be.

There appears to be a considerable element of fantasy-or desperate optimism-in Israeli planning. Despite the worldwide (including Israeli) intelligence fiasco over Iraq's nuclear and other military capabilities that preceded the war there, and despite the Israeli intelligence debacle that accompanied Israel's war against Hezbollah in 2006, defense experts in Israel continue to gloss over the possibility that some Iranian nuclear facilities could be unknown to Western intelligence agencies. Halevi and Oren quote a former Israeli defense official extrapolating, "If we can locate a suicide bomber as he moves from place to place, we know how to locate static targets, even deep underground." In the meantime, Israel's former prime minister, Benjamin Netanyahu, insists extravagantly that Israel currently possesses the capacity to "eliminate" the Iranian threat.

But it is physically possible to bury facilities so deeply that they cannot be destroyed even by large nuclear weapons. And we don't know where all the facilities are. Even many Israelis acknowledge that their best hope is that an attack would merely slightly delay Iran's nuclear development. If Tehran really does want to acquire nuclear weapons, there is no way this can be prevented, at least in the long term, except by invading the country-an enterprise that would likely make America's disastrous war in Iraq look like child's play.

Reinforcing the possibility of a futile attack are the many signs since the collapse of the Oslo peace process in 2000 that Israeli governments are no longer inclined to, or even capable of, thinking about the use of force as they traditionally have-as a pedagogical tool to convince enemies that it is better to accept the permanence of Israel's existence, right or wrong, than to suffer the consequences of trying to eliminate it. It used to be that Israel went to war when absolutely necessary-cleverly, carefully and with the force needed to win, but no more than that. Instead, Israel's strategy is now driven more by gut instinct than by rational planning. The main finding of the official commission established to investigate the debacle of the 2006 "Second Lebanon War" was that it was launched with no plan and no strategic purpose. In Gaza, Jenin and, potentially, Iran, Israel's military might has been, and may well be, deployed not to enhance future prospects for negotiations but to stave off perceived immediate threats or simply to satisfy emotional and psychological imperatives for action. Levels of destruction imposed on Muslim Middle Easterners are not evaluated as a necessary but unfortunate cost inflicted on prospects for peace. They are viewed instead as sources of emotional satisfaction or tactical effectiveness. That approach may gratify short-term desires, but it does not serve long-term needs.

And an attempt to destroy Iranian nuclear facilities would have significant negative consequences in the long term. If the experience with the 1981 Osirak bombings of Iraq holds, Iran's most likely response to an attack would be to launch a truly dedicated effort to obtain a bomb. Tehran might well see this as an absolute necessity, at the very least for defensive purposes.