One thing that Ehud Olmert's "slip of the tongue" on German television last week proved was that when Israel's prime minister talks about nuclear weapons, the world takes heed. After a great global gasping that Olmert had let the cat out of the bag, and despite the Prime Minister's Office denying that he had said what he had actually said, the inclusion of Israel in a list of nuclear powers opened up discussion on our own verboten "N-word" in a way that is rarely seen here. If any damage came of it, though, it was in the advice that so many hurried to give our talkative leader: Shut your mouth. Ambiguity must be preserved at all costs. Perhaps forgetting that Ephraim Katzir had already told the world that Israel had nuclear weapons in 1974, or that Moshe Dayan had told the world that Israel had nuclear weapons in 1981, or that Mordechai Vanunu had told the world that Israel had nuclear weapons in 1986, the chronically misguided Yossi Beilin summed up the finger waggers' view by saying that "The prime minister's amazing statement regarding nuclear capability indicates a lack of caution bordering on irresponsibility." How predictable. And how wrong. Sure, on first glance, keeping a tight lid on the specifics of Israel's nuclear capabilities is the right, level-headed way to go. Loose lips sink ships, and all that. Yet there is a kind of sophomoric hypocrisy in the way that Israeli pundits discuss our nuclear arsenal - reveling as they do in speaking coyly about the weapons that everyone knows we have, while at the same time vociferously defending the outdated policy of ambiguity. This charade ignores two undeniable facts: the first, that there has been absolutely nothing ambiguous about Israel's nuclear capabilities for at least two decades; and the second, that there is another approach altogether to the concept of nuclear deterrence. THIS OTHER approach is the polar opposite of the one to which Israel still stubbornly clings. Rather than hide behind a veil of faux secrecy, this approach suggests putting all the cards on the table. It is delineated methodically and exquisitely in a speech by America's secretary of defense Robert McNamara delivered in 1967 - a speech worth reviewing very carefully. "The cornerstone of our strategic policy," he said, "continues to be to deter nuclear attack upon the United States or its allies. We do this by maintaining a highly reliable ability to inflict unacceptable damage upon any single aggressor or combination of aggressors at any time during the course of a strategic nuclear exchange, even after absorbing a surprise first strike." McNamara called this capability assured destruction. "It is important to understand," he stressed, "that assured destruction is the very essence of the whole deterrence concept. We must possess an actual assured-destruction capability, and that capability also must be credible. The point is that a potential aggressor must believe that our assured-destruction capability is in fact actual, and that our will to use it in retaliation to an attack is in fact unwavering." In other words, if your enemy doesn't believe you'll use your weapon, then that weapon - no matter how fearsome it may be - is worthless. Statements like those made by Shimon Peres, to the effect that Israel has built nuclear warheads in the sole hope of dismantling them at the request of its enemies, undermine the very foundation of this element of deterrence. To prove that America's will to use nuclear weapons in retaliation to an attack was in fact unwavering, McNamara could not have relied on vague, milquetoast declarations of "capabilities" or "options," as Israel does. He had to publicly announce the dizzying array of measures the United States had undertaken to ensure that "[no] other nation, or combination of nations, would possess a first-strike capability against it." The list was staggering. "Our strategic offensive forces are immense: 1,000 Minuteman missile launchers, carefully protected below ground; 41 Polaris submarines carrying 656 missile launchers, with the majority hidden beneath the seas at all times; and about 600 long-range bombers, approximately 40 percent of which are kept always in a high state of alert. "Our alert forces alone carry more than 2,200 weapons, each averaging more than the explosive equivalent of one megaton of TNT. Four hundred of these delivered on the Soviet Union would be sufficient to destroy over one-third of her population and one-half of her industry. All these flexible and highly reliable forces are equipped with devices that ensure their penetration of Soviet defenses." IN ISRAEL, such candor is anathema. For our defense establishment, which is so secretive that it refuses even to divulge how many soldiers are in its standing army, announcing that we have nuclear weapons would be unthinkable - much more so announcing how many we have and what their destructive power is. But putting all this in terms that any Iranian can understand, the way McNamara put it to the Russians, is vital. Of course, there would be repercussions to abandoning our policy of ambiguity; an obvious one would be a strenuous push to force Israel to submit to inspections or give up its nuclear weapons. But Israel would be able to parry such attempts by pointing out that it is not the only nuclear power not to have signed the Nuclear Nonproliferation Treaty - Pakistan and India are the others - and by reaching an agreement about its nuclear program akin to the one that the United States has just reached with India. (Certain differences between India's situation and Israel's suggest that such a deal could be even easier to negotiate in our case.) As McNamara said in the beginning of his speech on that September day in 1967: "No sane citizen, political leader or nation wants thermonuclear war. But merely not wanting it is not enough." It takes a credible deterrent. Iran's fevered dash to develop awesome nuclear technology is a clear signal that we have lost that deterrent. To get it back, Israel will have to do something much bolder than simply making more roundabout hints at what may be hiding in the country's proverbial basement. Brutal honesty about the terrifying means at our disposal is the first step, and the easiest. So tell the world, Ehud. Tell the world!