As negotiations regarding Iran’s nuclear program drag on inconclusively, calls mount for the Obama administration to abandon diplomacy. Hawks in the United States routinely excoriate President Obama for engaging in “appeasement” and advocate a return to the confrontational mode of previous administrations. Indeed, many of them demand that Washington adopt a harder-line policy than ever before, replete with a new round of tough economic sanctions against Tehran. Even some relatively moderate participants in the policy debate argue that Washington is unlikely to achieve a meaningful agreement and should, therefore, back away from the negotiations .

To his credit, Obama has thus far vigorously resisted such pressure. And for the moment, the congressional drive to sabotage negotiations by passing legislation imposing an array of new sanctions has stalled. But that may be merely a brief respite for the White House, if progress is not made toward a comprehensive settlement to replace the interim agreement reached last year.

Shrill warnings that Tehran is merely using the negotiations to stall for time while it continues to pursue a covert nuclear-weapons program are becoming more frequent. Those warnings emanate both from hawkish circles in the United States and from some foreign governments— most notably, Israel . Such critics insist that Iran is on the verge of a “breakout”—an ability to build nuclear weapons in the near future. They also argue that the Obama administration’s naïve commitment to diplomacy is giving the clerical regime breathing space to reach that goal.

We should view such predictions with more than a dollop of skepticism. Hawks have repeatedly predicted that Iran is on the verge of barging into the global nuclear-weapons club. Indeed, R. James Woolsey, a leading neoconservative figure and director of the Central Intelligence Agency in Bill Clinton’s administration, warned in 1993 that Iran would likely be able to build nuclear weapons in eight to ten years. Similar alarmist projections have surfaced repeatedly from the usual suspects since that time. Iran, it appears, has been on the threshold of a nuclear “breakout” for more than two decades.

Clearly, we should not succumb to yet another episode of foreign-policy hawks crying wolf. But it is not enough to remain committed to a diplomatic process for dealing with Iran. If U.S. officials do not adopt more realistic expectations of what constitutes an achievable agreement that serves America’s security interests, the current negotiations will all too likely result in failure. Such an outcome would lead to pervasive disillusionment and the onset of an even more intense, dangerous crisis in U.S.-Iranian relations.

The foundation of a realistic policy is accepting that Iran will likely never agree to renounce all nuclear capabilities. Any Iranian regime will want the country to have control over some nuclear technology, including the nuclear fuel cycle. It is worthwhile to recall that Iran’s nuclear ambitions did not originate with the mullahs; they began in the early 1970s under the Shah. That suggests widespread, long-term support for such a goal, based on a variety of motives, ranging from national prestige to regional-security concerns. Even if the political equivalent of Thomas Jefferson came to power in Tehran, the resulting government still would be unlikely to accept the demand of American neoconservatives that Iran embrace abstinence regarding nuclear capabilities.

The challenge for U.S. diplomacy is to get Tehran to agree to some limitations on its nuclear program, enforced by international inspections and safeguards. Even the ability to achieve that goal is far from certain. U.S. officials need to ask themselves whether America’s security actually is jeopardized if Iran merely acquires the ability to build a nuclear weapon. It would seem that our primary focus ought to be on discouraging Iran from deploying a nuclear arsenal—a very different standard.

The task for U.S. diplomacy should be to convince the Iranian government that it is not in the country’s best interest to take the fateful step of deployment. That challenge might not be as difficult as it seems. Iranian leaders are both shrewd and realistic. They likely understand that deploying a nuclear deterrent could very well trigger a regional arms race that would leave Iran less secure than it is now. Tehran would gain little if it brandished an arsenal of a dozen or so warheads, only to see such countries as Saudi Arabia, Turkey and Egypt follow suit.

Washington should pursue a two-pronged strategy. One aspect would be a concerted effort to convince Tehran that while both the United States and Middle Eastern powers might be able to tolerate a situation in which Iran remains one screwdriver’s turn away from a nuclear-weapons capability, actually deploying an arsenal would be a game changer—and a counterproductive one at that. Second, Washington needs to move to normalize relations with Iran and make it clear to Iranian leaders that this country is out of the regime-change business. In other words, U.S. officials should take tangible steps to assure Iran that it does not need nuclear weapons as a deterrent against the United States. Washington’s blustering, menacing behavior throughout the world, especially during George W. Bush’s administration, conveyed the opposite message.

Hawks will, of course, reject such proposals as appeasement of an odious, radically aggressive regime. Discredited nightmarish scenarios, including Iran launching a nuclear attack on Israel out of the blue or transferring nuclear weapons to terrorist groups, will be again trotted out. Such horror stories assume that Iranian leaders are not merely irrational, but suicidal. There is no credible evidence for that assumption. Indeed, even the former head of Mossad, Israel’s intelligence agency, concedes that while the Iranian leadership is calculating and ruthless, it is also quite rational .

It is important for the Obama administration to spurn hawkish calls for an uncompromising policy toward Iran. But it is equally important for U.S. officials to adopt more realistic expectations about an attainable, worthwhile agreement on the nuclear issue. We are on the cusp of both opportunity for a much better relationship between Iran and the United States and the danger of a tragic breakdown in relations, with extraordinarily dangerous consequences.

Ted Galen Carpenter, a senior fellow at the Cato Institute and a contributing editor at the National Interest, is the author of nine books and more than 600 articles and policy studies on international affairs.