This argument has become so common, especially in Israel, that even political hacks like the Likud’s former foreign minister, Silvan Shalom, will repeat it glibly to Israeli radio correspondents without fear of contradiction. (None came—at least not when I was listening.) American conversations are no better. The only question that seems to come up now, even among our most reasonable observers, is whether an attack should be American at five minutes to midnight or Israeli at eleven thirty.

But the argument is preposterous on its face. And the claim that Israel—a country of six and a half million Jews and a million and a half restive Arabs—can provoke war with Iran—a country of 75 million, a regime desperate to redeem itself with a war economy, and stand for “Islam” against “the West”—and then manage the consequences requires a hubris only Thucydides, or Stanley Kubrick, could fully portray.

It is natural to assume that only military people fully understand the contingencies. And to make the argument preposterous, many expert people  have worked behind the schenes for years; to prepare Israel’s own nuclear capabilities. But although executing on nuclear strategy is rocket science, formulating it is not. Ordinary citizens can easily understand, if not easily fathom, the heart of “deterrence”: if you are a nuclear power and you want another one to refrain from attack, you have to prove that you have the means, and will, to retaliate in kind.

For Israeli leaders, the calculation is especially straightforward and the threat of retaliation utterly credible. It is an open secret (being open is part of the strategy) that the Israeli military has in excess of a hundred nuclear warheads. It also has the missiles and submarines necessary to absorb a first strike by Iran, hypothetically reducing Tel Aviv to rubble and ashes, and retaliate in kind, reducing Tehran, Qom, and the rest of Iran’s principal cities to rubble and ashes.

Yes, a bomb in Tel Aviv would arguably be the end of Israel, while retaliation would destroy “only” 20 million Iranians, every important mosque and manuscript, and every cultural remnant of Persian civilization.  But then, the very apocalyptic nature of the attack on Tel Aviv is what makes the threat of retaliation credible.  What would surviving IDF commanders have to lose—or Iranians gain?

Ah, but what if Iranian leaders are not “rational,” something like the folkloric Hitler in his bunker, in his last day, telling his (appalled) inner circle that German civilization should die because it proved unworthy of him? It troubles me to say how many of my otherwise intelligent Israeli friends justify a war with Iran in large part because they are anxious to prove themselves “not naïve” about hatred. Anything counts as proof of “irrationality,” including every pronouncement that Zionism was immoral and Israel should disappear, something you can hear even on the streets of Nazareth, and even in Hebrew, everyday. (By this logic, Eisenhower should have attacked the Soviet Union the moment Khrushchev said: “We will bury you.”)   

They really seem to believe, or, given the death-camps, seem embarrassed to refute, that the Ayatollah-in-chief would wake up one fine morning and decide that the sheer pleasure of destroying Israel is more compelling than the survival of everything he knows. And why? Because of what Israel did to the Palestinians and what this represents—Palestinians who, by the way, might not be incinerated by a strike of Tel Aviv, but would assuredly be irradiated by it. My God, if they hate us this much, why not attack with conventional weapons, enlist Iraqi Shia, roll over Jordan, and lose “only” a million or so? (That’s how many casualties Iran suffered in the eight year war with Saddam.)

The thing is, once you understand the holes in the argument for an Iranian first strike, the idea of a “nuclear umbrella” for clients falls to the ground: strategic advantage is not a function of total blasting power; and a nuclear bomb is not a “weapon” in the ordinary sense. It is, at best, a doomsday hedge against invasion or other existential threat to a regime, which is precisely why Israel acquired one, North Korea acquired one, and Iran wants one.

But if hostilities started-up again between Israel and Hezbollah, say, Iran would refrain from using a nuclear bomb because Israel (and its ally, America) has one, too. Indeed, why didn’t Hezbollah fear Israel’s “nuclear umbrella” when it attacked in 2006? America attacked Vietnam, though its patron had a thousand bombs. Where was the Soviet umbrella?

President Obama is trying to stop the most feverish talk, appealing for diplomacy and patience, dispatching Defense Secretary Panetta and General Dempsey to reassure Israelis that they will not stand alone. But he has also been cornering himself, buying into the preemptive war logic—if only temporarily, and for the sake of Dade County—insisting that America will do whatever is necessary to prevent Iran from acquiring a nuclear capability and, by implication, forcibly opposing any Iranian military activity in the Gulf.

This, I fear, is tantamount to putting American policy in the hands of Netanyahu and Barak, who would feel more brazen about starting the war of they were sure Obama, facing reelection, would have no alternative but to commit to finishing.

Obama, in these circumstances, cannot temporize. He or Secretary Clinton has to make clear, publicly, that it is America’s policy to oppose any unilateral Israeli attack, and, if this should come, Israel will have compromised America’s interests in the region. Obama has his peace prize. This is the moment to earn it.