The special relationship between Israel and the United States is about to enter perhaps its rockiest patch ever. Israel is growing exasperated with the Obama administration’s effort to use diplomacy to roll back Iran’s growing uranium-enrichment program. Israelis know better than anyone else that the trick to developing a nuclear weapon as a small power is to drag out the process of diplomacy and inspections long enough to produce sufficient quantities of fissionable material. Israel should know: in the 1960s, it deliberately misled U.S. inspectors and repeatedly delayed site visits, providing the time to construct its Dimona reactor and reprocess enough plutonium to build a bomb. North Korea has followed a similar path, with similar results. And now, Israel suspects, Iran is doing the same, only with highly enriched uranium instead of plutonium.

Most observers believe that Israel’s preoccupation with Iran’s nuclear program stems from the fear that Iran would either use a nuclear weapon against Israel or give the bomb to one of its direct proxies, most likely Hezbollah. Given Tehran’s open hostility toward Jerusalem, such foreboding makes sense. But such a scenario is highly improbable.

Tehran’s profound dislike of the Jewish state notwithstanding, it is unlikely to attack Israel with a nuclear weapon because Israel’s atomic arsenal is orders of magnitude larger than whatever infant capability Iran could muster in the foreseeable future. Moreover, Israel is believed to possess a secure submarine-based second-strike capability that could devastate Iran.

Nor would Iran readily supply Hezbollah with atomic weapons. No nuclear state has ever turned over its most prized military asset to a subsidiary actor or surrendered its exclusive control over a weapon that it worked so hard to obtain. More important, if Hezbollah were to acquire and use a nuclear weapon against Israel, there would be no doubt about the weapon’s provenance and Iran would immediately face devastating retaliation. An attack on Israel, in other words, would mean the end of Iran.

Although many analysts question the rationality of the Iranian regime, it is in fact fairly conservative in its foreign policy. Iran has two long-range goals, achieving regional hegemony and spreading fundamentalist Islam, neither of which will be achieved if Iran initiates a nuclear exchange with Israel. Tehran’s expanding influence in Iraq and the fear that it inspires in the Persian Gulf states are already advancing the first goal. Iran needs only to possess nuclear weapons, not to use them, in order to further enhance its international prestige and force adversaries to take it seriously. Likewise, the deterrent power of an unused nuclear capability would allow the regime to spread its ideology without the constant worry of regime change imposed from abroad.

Since it is doubtful that Iran will use nuclear weapons against Israel or surrender control of the ultimate weapon to Hezbollah -- a point made recently by retired General Shlomo Gazit in Ma’arachot, the quarterly journal published by the Israeli military -- one can safely assume that the root of Israel’s Iranian obsession lies elsewhere.

Israel fears that Iran’s nuclear ambitions could undermine its qualitative superiority of arms and its consistent ability to inflict disproportionate casualties on adversaries -- the cornerstones of Israel’s defense strategy. Although some idealists dream of reconciliation in the Middle East based on a genuine and mutual recognition of all parties’ legitimate rights, most Israelis believe the key to enduring peace in the Middle East is convincing Israel’s adversaries that ejecting Israel through force is an impossible task not worth pursuing.

Essential to inducing that sense of despair is Israel’s ability to continuously trounce its enemies on the battlefield and suffer far fewer losses than it inflicts. The Iranian nuclear program threatens Israel’s ability to do this in two ways. First, an Iranian nuclear capability would likely force Israel to restrain itself due to fears that Iran’s nuclear weapons could provide an implied security guarantee to other anti-Zionist forces -- the sort of guarantee that would prevent Israel from causing the massive losses it has in the past, while giving anti-Israel forces the confidence to keep up the fight.

Israeli restraint during a war could take many forms, but it is unlikely that the unmitigated rout of the 1967 Six-Day War or the direct threat posed to Arab capitals at the end of the 1973 Yom Kippur War would have occurred if a nuclear guarantee had been forthcoming from a true regional adversary such as Iran, rather than from a distant superpower such as the Soviet Union, whose chief interest lay in the humiliation of its rival, not the destruction of Israel.

The even greater threat posed by Iran’s nuclear program is its potential to unleash a cascade of proliferation in the Middle East, beginning with Egypt and Saudi Arabia. For both of these states, the idea that Jews and Persians could have a monopoly on nuclear weapons in a region demographically and culturally dominated by Arabs is shameful. For Saudi Arabia, a security motivation will be at play as well, given its physical proximity to Iran and the strategic imperative of deterring any Iranian threat to Saudi Arabia’s oil-production facilities.

The development of nuclear weapons by Egypt or Saudi Arabia would pose a grave danger to the Jewish state, despite the fact that Egypt has signed a peace treaty with Israel. This is because leaders who have reconciled themselves to Israel’s existence -- including those of Egypt, Jordan, and certain segments of the Palestinian national movement -- have done so because they believed Israel was strong but unlikely to endure in the long term. (Egyptian President Anwar Sadat, for example, justified his pursuit of a peace process with Israel by comparing the Israelis to crusaders: strong today, gone tomorrow.) More broadly, as the Palestinian-American political scientist Hilal Khashan’s work on Arab attitudes toward peace has shown, the willingness of Arabs to make peace with Israel is a direct function of their perception of Israel’s invincibility. Just as an Iranian nuclear capability would imply a nuclear guarantee for anti-Zionist proxies, an Egyptian or Saudi nuclear capability would reduce incentives for other Arab states to make peace with Israel because, shielded under an Arab nuclear umbrella, they would no longer fear catastrophic defeat or further loss of territory.

Such developments would shatter the perception of Israeli invincibility on which successive Israeli governments have pinned their hopes for eventual peace in the region. As a result, Israel’s security would be dependent on maintaining a state of perpetual armed readiness and hair-trigger alert that could counter immediate threats but only in an inconclusive manner, as displayed recently in Lebanon and Gaza. The restraint that Israel showed in both conflicts out of deference to U.S. and European concerns would only be magnified by the new fear of crossing an Arab red line. Future operations resembling the 2006 invasion of Lebanon or the January 2009 attack on Gaza are likely to be even more restrained and therefore, by Israel’s own metric, less effective in pushing Arabs toward peace. In fact, such operations may do Israel more harm than good, because as Israel uses less force and causes less damage, the deterrent effect that Israel hopes to bolster through such operations only gets further eroded.

The possibility that Israel may no longer be capable of forcing peace upon those who deny its right to exist is beginning to dawn on many Israelis. Whether Israel attacks Iran’s nuclear infrastructure or not, the time has come for Israel’s defense community to develop a strategic doctrine for long-term coexistence that does not rely on a posture of invincibility. But, given that widespread Arab acceptance of Israel’s right to exist does not appear to be on the horizon, most Israelis, including the current prime minister, insist that Israel’s most urgent strategic objective is to stop Iran from developing a nuclear weapon. Doing so would temporarily remove the threat of a regional nuclear cascade and maintain Israel’s superiority of arms. More important, it would hold at bay the suspicion that Israel may never attain true peace. This increasingly widespread fear has a toxic effect on national morale, is an existential threat to the Jewish state, and lies at the root of Israel’s obsession with the Iranian bomb.