President Obama's Iran policy has, in all likelihood, already failed. On its present course, the White House's approach will not stop Tehran's development of a nuclear fuel program - or, as Iran's successful test of a medium-range, solid-fuel missile last week underscored, military capacities of other sorts. It will also not provide an alternative to continued antagonism between the United States and Iran - a posture that for 30 years has proved increasingly damaging to the interests of the United States and its allies in the Middle East.

This judgment may seem both premature and overly severe. We do not make it happily. We voted for Barack Obama in 2008, and we still want him to succeed in reversing the deterioration in America's strategic position. But we also believe that successful diplomacy with Iran is essential to that end. Unless President Obama and his national security team take a fundamentally different approach to Tehran, they will not achieve a breakthrough.

This is a genuine shame, for President Obama had the potential to do so much better for America's position in the Middle East. In his greeting to "the people and leaders of the Islamic Republic of Iran" on the Persian New Year in March, Mr. Obama included language meant to assuage Iranian skepticism about America's willingness to end efforts to topple the regime and pursue comprehensive diplomacy.

Iranian diplomats have told us that the president's professed willingness to deal with Iran on the "basis of mutual interest" in an atmosphere of "mutual respect" was particularly well received in Tehran. They say that the quick response of the nation's supreme leader, Ayatollah Ali Khamenei - which included the unprecedented statement that "should you change, our behavior will change, too" - was a sincere signal of Iran's openness to substantive diplomatic proposals from the new American administration.

Unfortunately, Mr. Obama is backing away from the bold steps required to achieve strategic, Nixon-to-China-type rapprochement with Tehran. Administration officials have professed disappointment that Iranian leaders have not responded more warmly to Mr. Obama's rhetoric. Many say that the detention of the Iranian-American journalist Roxana Saberi (who was released this month) and Ayatollah Khamenei's claim last week that America is "fomenting terrorism" inside Iran show that trying to engage Tehran is a fool's errand.

But this ignores the real reason Iranian leaders have not responded to the new president more enthusiastically: the Obama administration has done nothing to cancel or repudiate an ostensibly covert but well-publicized program, begun in President George W. Bush's second term, to spend hundreds of millions of dollars to destabilize the Islamic Republic. Under these circumstances, the Iranian government - regardless of who wins the presidential elections on June 12 - will continue to suspect that American intentions toward the Islamic Republic remain, ultimately, hostile.

In this context, the Saberi case should be interpreted not as the work of unspecified "hard-liners" in Tehran out to destroy prospects for improved relations with Washington, but rather as part of the Iranian leadership's misguided but fundamentally defensive reaction to an American government campaign to bring about regime change. Similarly, Ayatollah Khamenei's charge that "money, arms and organizations are being used by the Americans directly across our western border to fight the Islamic Republic's system" reflects legitimate concern about American intentions. Mr. Obama has reinforced this concern by refusing to pursue an American-Iranian "grand bargain" - a comprehensive framework for resolving major bilateral differences and fundamentally realigning relations.

More broadly, President Obama has made several policy and personnel decisions that have undermined the promise of his encouraging rhetoric about Iran. On the personnel front, the problem begins at the top, with Secretary of State Hillary Clinton. As a presidential candidate, then-Senator Clinton ran well to the right of Mr. Obama on Iran, even saying she would "totally obliterate" Iran if it attacked Israel. Since becoming secretary of state, Clinton has told a number of allies in Europe and the Persian Gulf that she is skeptical that diplomacy with Iran will prove fruitful and testified to Congress that negotiations are primarily useful to garner support for "crippling" multilateral sanctions against Iran.

First of all, this posture is feckless, as Secretary Clinton does not have broad international support for sanctions that would come anywhere close to being crippling. More significantly, this posture is cynically counterproductive, for it eviscerates the credibility of any American diplomatic overtures in the eyes of Iranian leaders across the Islamic Republic's political spectrum.

Even more disturbing is President Obama's willingness to have Dennis Ross become the point person for Iran policy at the State Department. Mr. Ross has long been an advocate of what he describes as an "engagement with pressure" strategy toward Tehran, meaning that the United States should project a willingness to negotiate with Iran largely to elicit broader regional and international support for intensifying economic pressure on the Islamic Republic.

In conversations with Mr. Ross before Mr. Obama's election, we asked him if he really believed that engage-with-pressure would bring concessions from Iran. He forthrightly acknowledged that this was unlikely. Why, then, was he advocating a diplomatic course that, in his judgment, would probably fail? Because, he told us, if Iran continued to expand its nuclear fuel program, at some point in the next couple of years President Bush's successor would need to order military strikes against Iranian nuclear targets. Citing past "diplomacy" would be necessary for that president to claim any military action was legitimate.

Iranian officials are fully aware of Mr. Ross's views - and are increasingly suspicious that he is determined that the Obama administration make, as one senior Iranian diplomat said to us, "an offer we can't accept," simply to gain international support for coercive action.

Understandably, given that much of Mr. Obama's national security team doesn't share his vision of rapprochement with Iran, America's overall policy is incoherent. For example, while the administration recently completed a much-ballyhooed review of Iran policy, it has made no changes in its approach to the nuclear issue. Administration officials argue, with what seem to be straight faces, that the Iranian leadership should be impressed simply because American representatives will now show up for any nuclear negotiations with Iran that might take place.

Similarly, some officials suggest that the administration might be prepared to accept limited uranium enrichment on Iranian soil as part of a settlement - effectively asking to be given "credit" merely for acknowledging a well-established reality. Based on our own experience negotiating with Iranians, and our frequent discussions with Iranian diplomats and political figures since leaving the government, we think that it will take a lot more to persuade Tehran of America's new seriousness.

Tehran will certainly not be persuaded of American seriousness if Washington acquiesces to Israeli insistence on a deadline for successful American engagement with Iran. Although the White House spokesman, Robert Gibbs, had told reporters that no such deadline would be imposed, President Obama himself said, after his meeting with Prime Minister Benjamin Netanyahu of Israel, that he wants to see "progress" in nuclear negotiations before the end of the year. He also endorsed the creation of a high-level Israeli-American working group to identify more coercive options if Iran does not meet American conditions for limiting its nuclear activities.

More specifically, Secretary Clinton and Mr. Ross have been pushing the other permanent members of the United Nations Security Council and Germany to intensify multilateral sanctions against Iran if Tehran has not agreed to limit the expansion of its nuclear-fuel cycle program by the time the United Nations General Assembly convenes in New York at the end of September.

This diplomatic approach is guaranteed to fail. Having a deadline for successful negotiations will undercut the perceived credibility of American diplomacy in Tehran and serve only to prepare the way for more coercive measures. Mr. Obama's justification for a deadline - that previous American-Iranian negotiations produced "a lot of talk but not always action and follow-through" - is incorrect as far as Iranian behavior was concerned. For example, during talks over Afghanistan after 9/11 in which one of us (Hillary) took part, Tehran deported hundreds of Qaeda and Taliban operatives who had sought sanctuary in Iran, and also helped establish the new Afghan government. It was Washington, not Tehran, that arbitrarily ended these productive talks.

Beyond the nuclear issue, the administration's approach to Iran degenerates into an only slightly prettified version of George W. Bush's approach - that is, an effort to contain a perceived Iranian threat without actually trying to resolve underlying political conflicts. Obama administration officials are buying into a Bush-era delusion: that concern about a rising Iranian threat could unite Israel and moderate Arab states in a grand alliance under Washington's leadership.

President Obama and his team should not be excused for their failure to learn the lessons of recent history in the Middle East - that the prospect of strategic cooperation with Israel is profoundly unpopular with Arab publics and that even moderate Arab regimes cannot sustain such cooperation. The notion of an Israeli-moderate Arab coalition united to contain Iran is not only delusional, it would leave the Palestinian and Syrian-Lebanese tracks of the Arab-Israeli conflict unresolved and prospects for their resolution in free fall. These tracks cannot be resolved without meaningful American interaction with Iran and its regional allies, Hamas and Hezbollah.

Why has President Obama put himself in a position from which he cannot deliver on his own professed interest in improving relations with the Islamic Republic? Some diplomatic veterans who have spoken with him have told us that the president said that he did not realize, when he came to office, how "hard" the Iran problem would be. But what is hard about the Iran problem is not periodic inflammatory statements from President Mahmoud Ahmadinejad or episodes like Ms. Saberi's detention. What is really hard is that getting America's Iran policy "right" would require a president to take positions that some allies and domestic constituencies won't like.

To fix our Iran policy, the president would have to commit not to use force to change the borders or the form of government of the Islamic Republic. He would also have to accept that Iran will continue enriching uranium, and that the only realistic potential resolution to the nuclear issue would leave Iran in effect like Japan - a nation with an increasingly sophisticated nuclear fuel-cycle program that is carefully safeguarded to manage proliferation risks. Additionally, the president would have to accept that Iran's relationships with Hamas and Hezbollah will continue, and be willing to work with Tehran to integrate these groups into lasting settlements of the Middle East's core political conflicts.

It was not easy for President Richard Nixon to discard a quarter-century of failed policy toward the People's Republic of China and to reorient America's posture toward Beijing in ways that have served America's interests extremely well for more than 30 years. That took strategic vision, political ruthlessness and personal determination. We hope that President Obama - contrary to his record so far - will soon begin to demonstrate those same qualities in forging a new approach toward Iran.