Practically every aspect of the National Intelligence Estimate report on the Iranian nuclear program raises questions about its methodology and conclusions, and many of these questions have already been aired.

Were the report’s framers politically motivated? Were they taken in by Iranian counterintelligence, which may have planted some or all of the “evidence” interpreted to indicate that the Iranian nuclear weapons program was suspended in 2003? And if it was suspended, why was it suspended when it was and why has Iran continued to develop long-range ballistic missiles capable of carrying nuclear warheads, pressed ahead with uranium enrichment, and resisted international inspection? And can it be that the NIE, even if right about suspension, is overly sanguine about the amount of time it would take the Iranians to reinstate such a program and build a nuclear weapon?

Whatever the answers to these questions turn out to be, the immediate effect of the NIE report is clear. The United States will not attack Iran’s nuclear installations in the remaining year of the Bush administration and neither will Israel, which cannot contemplate such an action either now or in the future without full American political and military collaboration. The “will they/won’t they” bets are off. They won’t. It needs to be said that both for the average Israeli and for the nation’s political and military leadership, however distrustful of the NIE report they might be, there is a measure of relief in such knowledge. No one in Israel had any illusions about an assault on Iran going unresponded to by the Iranians and their allies in Lebanon, Gaza, and possibly Syria. Such a response might mean dozens or hundreds of Israeli casualties and a relatively small amount of physical damage, or it might mean many thousands of casualties and widespread damage. No one can know for sure, just as no one can know how successful an attack on Iranian nuclear installations would be. To think that anyone in Israel has been champing at the bit to find this out is to imagine a trigger-happier country than the one that exists.

But there is no point, either, in minimizing the NIE report’s dangers to Israel. If the report is mistaken about Iranian realities or intentions, any reassessment may come too late. The American intelligence community is not going to be eager to reverse the report’s conclusions any time soon, and even if it were to do so, President Bush’s successor is unlikely to have Mr. Bush’s willingness or determination to act against Iran.

Nor are there now going to be stronger international sanctions against Iran. On the contrary: as much as the Bush administration may try to push the argument that the supposed 2003 suspension of Iran’s nuclear program was brought about by the threat of sanctions, which should therefore be jacked up even more now, countries like Russia and China, or even most of America’s European allies, are not going to buy it. If they have been loathe to sacrifice their perceived political and economic interests for the sake of sanctions up to now, they can be counted on to point to the NIE report as proof that there is even less reason to do so in the future. And so if Iran has been covertly continuing its nuclear weapons program all along, there will no longer be anything or anyone capable of stopping it.

For Israel, this will mean having to learn to live with a nuclearized Iran. The implications are potentially enormous and financially burdensome. They would start with having to strengthen Israel’s nuclear deterrent by beefing up its already expanding anti-missile defenses and second-strike capability; include a concerted campaign to keep the Arab Middle East from going the way of Iran; provide for a large investment in technological means for detecting and preventing the smuggling by terrorists of possible Iranian-made nuclear devices into Israel; and end with the need for a major build-up of Israel’s conventional armed might as well.

The latter point needs to be stressed. Israel’s military posture toward the Arab world so far has been based on the assumption that, were Israel ever in danger of losing a war, it could count on its nuclear deterrent to put a stop to the fighting in time. Indeed, in the early days of the 1973 Yom Kippur War, when defeat loomed as a possibility, Israel reportedly did consider deploying nuclear weapons, and the assumption that it might was one reason for the Egyptians’ and Syrians’ limited war aims following their initial successes.

An Iranian nuclear arsenal would neutralize this deterrent by providing the Arabs with a nuclear umbrella. Israel would no longer be able to take even the slight risks with its military security that it might be able to afford otherwise. It would also have to think far more carefully about making territorial concessions, both to the Palestinians and to the Syrians. Control of the Jordan Valley and the Golan Heights, militarily valuable in any case, might come to seem crucial, making these areas unsurrenderable.

Those who have accused the NIE report of hiding a political agenda have intimated that this was to prevent an American or Israeli attack on Iran from disturbing the peace in the Middle East. If there is any truth to this, one wonders whether the report’s framers took into account its more long-term effects on Israel. An Israel living in fear of a nuclear Iran will have to leave itself far greater margins of safety. These will not necessarily be conducive to the kind of Middle East that the NIE’s authors would like to envision.

Mr. Halkin is a contributing editor of The New York Sun.