In this 2013 photo released by the official website of the office of the Iranian Presidency, Iranian President Hassan Rouhani speaks during an interview with state television in Tehran. Rouhani is set to address the U.N. on Tuesday. (Rouzbeh Jadidoleslam/AP) 
 
 In the often colorless realm of international diplomacy, one annual ritual has stood out for years — a provocative speech by Iran’s leader to the United Nations each September, followed by a walkout by U.S. and Israeli delegates. 
 
 That bit of diplomatic theater may not happen this year, as a new Iranian president who has alternately pleased, intrigued and startled American observers makes his debut trip to the annual gathering of world leaders in New York. 
 
 No one, including Obama administration officials, knows what might happen instead. 
 
 Iranian President Hassan Rouhani and President Obama are set to address the world body on Tuesday, with the tantalizing prospect of a face-to-face meeting between the leaders of two nations so long poised as enemies. 
 
 Rouhani’s speech is expected to be the main event in nearly a week of interviews, think-tank talks and other appearances meant to showcase a newly moderate, approachable face of the Iranian government. The charm offensive included an op-ed by the Iranian leader in Friday’s Washington Post. 
 
 “As I depart for New York for the opening of the U.N. General Assembly, I urge my counterparts to seize the opportunity presented by Iran’s recent election,” Rouhani wrote in the op-ed. “I urge them to make the most of the mandate for prudent engagement that my people have given me and to respond genuinely to my government’s efforts to engage in constructive dialogue.” 
 
 U.S. officials say they have been encouraged by recent gestures from Rouhani, including the public discussion of his country’s disputed nuclear program — the crux of Iran’s standoff with the West. Obama has said he will do whatever it takes, including a military strike, to stop Iran from building a bomb. Rouhani said in a television interview this week that his country will never seek nuclear weapons. 
 
 “There’s no question that the new Iranian government has been taking a different approach in the things that it has said about a lot of issues,” White House press secretary Jay Carney said Thursday. “It has taken some actions that suggest a new approach.” 
 
 Carney and other U.S. officials, however, have been careful not to embrace Rouhani without reservations and have emphasized that Iran’s stated desire to improve relations with the international community needs to be followed up with concrete steps. 
 
 “Rouhani’s comments are very positive, but everything needs to be put to the test, and we’ll see where we go,” Secretary of State John F. Kerry said Thursday. 
 
 A contrast to Ahmadinejad 
 
 The barrage of friendly Iranian gestures marks a U-turn away from the rhetoric of Rouhani’s immediate predecessor, Mahmoud Ahmadinejad, who for a decade regularly denounced the United States and Israel and suggested that the Holocaust was a myth. 
 
 If Obama is to make good on his 2008 campaign promise to explore the possibility of improved relations and a nuclear rapprochement with Iran, the U.N. meeting this year appears to be his best chance yet. 
 
 Rouhani stunned many with a Rosh Hashanah greeting to Jews this month and announced Thursday that he will bring Iran’s only Jewish member of parliament with him to New York. 
 
 This week, Iran’s supreme leader, Ayatollah Ali Khamenei, signaled a willingness to begin negotiations on the nuclear issue. Iran also released several high-profile political prisoners. 
 
 Carney said there is no meeting scheduled between Rouhani and Obama. But Rouhani has suggested that he is open to a meeting, which would be the first such contact since 1979, when the countries broke off relations after Iranian students stormed the U.S. Embassy in Tehran and held 52 Americans hostage for 444 days. 
 
 Rouhani told NBC News that he welcomed a letter of congratulations that Obama sent him last month. “From my point of view, the tone of the letter was positive and constructive,” Rouhani said through an interpreter. 
 
 Since taking office last month, Rouhani and his U.S.-educated foreign minister, Mohammad Javad Zarif, have offered a unified vision of Iran’s foreign policy agenda. That is in stark contrast to the hodgepodge of the Ahmadinejad years, when different centers of power competed for influence. 
 
 Rouhani also appears to have the support of Iran’s supreme leader, who has long been the ultimate arbiter of the country’s nuclear decisions. 
 
 That endorsement brings an air of authority to Rouhani’s calls for increased openness toward the West, said Dennis Ross, a former senior adviser on the Middle East to the Obama White House. 
 
 “The fact that the Iranians, including the supreme leader, are publicly indicating a readiness to talk means they are preparing the ground for such engagement,” Ross said. 
 
 High stakes for Iran, West 
 
 Still, there is more at stake now, with Iran closer to the point at which it could build a bomb if it chose to do so and its economy wobbling under the weight of international sanctions imposed because of the nuclear dispute. 
 
 Veterans of past negotiations with Iran said they fear that Rouhani’s team may not yet grasp the kinds of concessions that the Islamic republic would be required to make to win relief from the most painful economic sanctions, such as restrictions on banking transactions and oil sales. Iranian officials have hinted at a willingness to accept minor limits on their nuclear program, which would not prevent a quick drive for a bomb. 
 
 “Charm alone is insufficient to achieve the kind of sanctions relief they’re looking for,” said Gary Samore, who until early this year was Obama’s principal adviser on arms control and weapons of mass destruction. “So far I haven’t seen the Iranians indicating a willingness to take the dramatic steps necessary to lift the biggest sanctions.” 
 
 Zarif, who is well known to U.S. officials as Iran’s ambassador to the United Nations from 2002 to 2007, is already in New York. He hosted a closed-door luncheon for more than 100 U.N. diplomats on Thursday. A participant, speaking on the condition of anonymity to detail the private session, said Zarif welcomed signs that “drums of war in the region” were going silent and vowed to resolve concerns about Iran’s nuclear program. 
 
 Kerry and Zarif may meet on the sidelines of the U.N. session, though neither side has announced any specifics. 
 
 Samore said the best hope for progress in New York this year could be establishing a forum for direct, if low-level, talks between the U.S. and Iranian governments, building a foundation for a future nuclear accord. 
 
 Some of the proposals floated in recent days suggest that Iran is setting the stage for a possible deal with the bloc of six nations that has engaged in intermittent negotiations with the country over several years. But Western diplomats and policy experts say the issues in contention are probably too complex for meetings on the sidelines of the U.N. conference. 
 
 For now, Iranian hard-liners who have championed their country’s nuclear capability appear to be sidelined, said Mohammad Ali Shabani, a Tehran political analyst. If Rouhani’s overtures yield nothing, Shabani said, there will be a political and public backlash. 
 
 “Right now, this government’s hands aren’t tied, but that won’t last forever. Right now, hands are open,” he said. 
 
 Rezaian reported from Tehran. Colum Lynch at the United Nations and Joby Warrick in Washington contributed to this report. ||||| The Iranian leadership was encouraged by what was described as Mr. Obama’s offer to conduct face-to-face talks, which they prefer to the more bureaucratic and lengthy negotiating process with a group of five major world powers, Mr. Mohebbian said. 
 
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 The one-and-a-half-page letter, which the Iranian president answered with a letter of similar length, has kindled hopes that the international charm offensive Iran began after Mr. Rouhani’s election in June may produce a genuine diplomatic breakthrough. But the differing interpretations of Mr. Obama’s letter in Tehran and Washington are a reminder of the political hurdles and the legacy of mistrust that both sides will have to overcome in negotiating a deal. 
 
 The American official said Mr. Obama had congratulated Mr. Rouhani on his election, and characterized the vote as an opportunity for change. But on sanctions, the official said, the Iranians were inferring relief from the president’s more general pledge to resolve issues and move forward. And while Mr. Obama is open to direct talks, the official said, they will not necessarily be leader to leader. 
 
 The Iranian reaction to the letter provides critical insight into a decisive and unexpected shift in strategy by the moderate new president as Iran struggles to restore vitality to its economy and undo years of hostile relations with most of the world under the former president, Mahmoud Ahmadinejad. 
 
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 The overtures to the United States are part of a flurry of steps altering the trajectory of the Iranian state, including domestic liberalizations and returning the politically powerful military to the barracks — for now. Those actions, along with the changed diplomatic tone, have convinced some experts that the changes are more than cosmetic. 
 
 Mr. Rouhani will present Iran’s new face to world next week with an address to the United Nations General Assembly, an evening speech to the Council on Foreign Relations and the Asia Society, and a television interviews with Charlie Rose and CNN. 
 
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 In an opinion essay published in The Washington Post on Friday, Mr. Rouhani said world leaders should “seize the opportunity presented by Iran’s recent election.” 
 
 “I urge them to make the most of the mandate for prudent engagement that my people have given me and to respond genuinely to my government’s efforts to engage in constructive dialogue,” he wrote. 
 
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 Skeptics were quick to point out that Mr. Obama has reached out to Iran before. Having promised as a candidate to extend an olive branch to old enemies, he sent a letter early in his first term to the country’s supreme leader, Ayatollah Ali Khamenei, proposing a new diplomatic chapter. In his reply, Ayatollah Khamenei did not take Mr. Obama up on his offer. 
 
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 Their correspondence was cut short after Iran’s disputed presidential election in June 2009 unleashed a popular uprising. The ensuing bloody crackdown all but snuffed out diplomacy for the next year. Mr. Ahmadinejad, re-elected as president, wrote a lengthy letter to Mr. Obama in 2010, but it did nothing to break the diplomatic ice. 
 
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 This time Mr. Obama’s letter found a receptive audience, which apparently, and crucially, includes for the first time Ayatollah Khamenei. Mr. Mohebbian said he had been present at an official meeting of the leadership at which the letter was read aloud and discussed by someone from “the highest levels” of Iran’s political establishment, terminology that usually describes the office of the supreme leader. 
 
 Mr. Mohebbian, who often acts as a political commentator for foreign news media, published parts of the letter on Tuesday on one of the 20 Web sites he runs in Iran, called Secretnews. 
 
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 Mr. Mohebbian said the Iranian leadership was generally receptive to the letter except for what he said was Mr. Obama’s complimenting Mr. Rouhani as “the representative of the Iranian people, not of the totalitarian leaders.” 
 
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 This is the first time Mr. Obama has written directly to an Iranian president, and not the supreme leader, suggesting that the White House believes Ayatollah Khamenei has empowered Mr. Rouhani to seek an opening with the West. 
 
 In a sharp break with previous letter exchanges, both presidents have publicly lauded their correspondence. Mr. Rouhani said in an NBC News interview broadcast on Wednesday that the tone of Mr. Obama’s letter was “positive and constructive.” He added, “It could be subtle and tiny steps for a very important future.” 
 
 Mr. Obama, speaking to the Spanish-language network Telemundo on Tuesday, said there were indications that Mr. Rouhani “is somebody who is looking to open dialogue with the West and with the United States, in a way that we haven’t seen in the past. And so we should test it.” 
 
 In his reply to Mr. Obama, Mr. Rouhani said public opinion in Iran did not favor talks, Mr. Mohebbian said. Iran’s president urged Mr. Obama to “prepare the grounds for successful negotiations” with a gesture of good faith. 
 
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 The American official said that while Mr. Rouhani was frank about policy differences with the United States, his letter, too, had a different tone — less the list of grievances that he said characterized letters from Ayatollah Khamenei or Mr. Ahmadinejad. 
 
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 Iran’s leaders are apparently convinced that the next six months, before campaigning begins for parliamentary elections in March, represent the best opportunity to reach a nuclear agreement in over a decade, Mr. Mohebbian said. 
 
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 The leaders considered the tone of Mr. Obama’s letter a very promising sign, and paradoxically, they view what they see as America’s declining regional influence as a positive. Mr. Rouhani has publicly applauded Mr. Obama’s decision to refrain from striking Syria for its poison gas attack on its own civilians. 
 
 Mr. Mohebbian said Ayatollah Khamenei had been growing concerned about the future of the revolution, with so many of its founders aging. In particular, he wants to settle the nuclear issue and ease tensions with the United States. 
 
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 “It is the leader who decides on the possibility, scope and extent of potential talks with the U.S.,” Mr. Mohebbian said. He emphasized that Ayatollah Khamenei was in excellent health, “but we need him to reach consensus within our system.” 
 
 “He feels this is the moment to try and solve this problem.” 
 
 The leadership is also desperate to escape the withering financial sanctions imposed in recent years, particularly the ban on Iranian money transfers through the Swift system. It can live without oil sales, analysts have said, but not without the ability to transfer money. 
 
 Mr. Mohebbian said Iran is hoping that the White House will lift some sanctions as a gesture to show its seriousness about the talks. “We particularly want to be readmitted to the Swift system,” he said. 
 
 He and other analysts warned that while Iran’s political establishment fully agreed that talks were worth trying, the consensus could break down within months if there were no results. 
 
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 “The world must know that time is not unlimited for solving the nuclear problem,” Mr. Rouhani said in his first live television interview on Iranian state television, on Sept. 10. 
 
 At the White House, where Mr. Obama has long sought a rapprochement with Iran but been repeatedly frustrated, officials share the sense that this time may be different. 
 
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 “Rouhani is sending signals he wants to deal,” said Dennis B. Ross, a former adviser to Mr. Obama on Iran. “He wants to end the sanctions and knows he does not have a lot of time to deliver — Iranian presidents have some space in their first year and then it declines.” ||||| WASHINGTON — Signaling a possible thaw in long-frozen relations, the Obama administration and the new leadership in Iran are communicating about Syria and are moving behind the scenes toward direct talks that both governments hope can ease the escalating confrontation over Tehran's nuclear program. 
 
 President Obama reportedly reached out to Iran's relatively moderate president, Hassan Rouhani, through an exchange of letters in recent weeks. The pragmatist cleric is scheduled to address the United Nations General Assembly on Sept. 24, and after years of the United States cold-shouldering his ultraconservative predecessor, U.S. officials say it's possible they will meet with Rouhani on the sidelines. 
 
 Beyond that, U.S. and Iranian officials are tentatively laying the groundwork for potential face-to-face talks between the two governments, the first in the rancorous 34 years since radical students seized the U.S. Embassy in Tehran and founded the Islamic theocracy. Diplomatic relations have been broken ever since. 
 
 Both governments have issued conciliatory public statements in recent days that suggest a new willingness to scale back the tension. 
 
 Obama suggested in four TV interviews this week, for example, that Iran had played a constructive role in pushing Syrian President Bashar Assad to refrain from using chemical weapons. Iran is one of Syria's closest allies and supplies conventional arms to Assad's forces, so Rouhani may have considerable leverage in the Russian-led effort to disarm Syria of its toxic weapons. 
 
 "You know, one reason that this may have a chance of success is that even Syria's allies, like Iran, detest chemical weapons," Obama told CNN. "Iran, you know, unfortunately was the target of chemical weapons at the hands of Saddam Hussein back during the Iraq-Iran War.... And you know, I suspect that some of Assad's allies recognize the mistake he made in using these weapons and it may be that he is under pressure from them as well." 
 
 Washington and Tehran have exchanged private messages about the civil war in Syria, according to Iran's new foreign minister, Mohammad Javad Zarif, although he didn't reveal the substance. Analysts say Iran is trying to avoid having the Syrian chemical weapons crisis damage prospects for a potential resolution of Tehran's nuclear standoff with the West. 
 
 Zarif's prominent role marks a clear shift in Tehran. The graduate of San Francisco State University and the University of Denver, and a popular diplomat when he was Iran's envoy to the United Nations from 2002 to 2007, has been named to lead Iran's nuclear negotiating team. 
 
 Rouhani was elected in June after promising voters he would allow greater personal freedom and strengthen the economy. 
 
 Since he took office, Iran has scaled back its anti-Western invective and muted the Holocaust denials associated with the previous president, Mahmoud Ahmadinejad. In perhaps the most jaw-dropping sign of change, Rouhani apparently sent a tweet this month wishing Jews a happy Rosh Hashana, the Jewish New Year. 
 
 White House officials said Wednesday that they wouldn't confirm or comment on Obama's private correspondence. But Bernadette Meehan, a spokeswoman for the National Security Council, said the administration was ready to talk if Iran was serious. 
 
 Rouhani's election "presents an opportunity for Iran to act quickly to resolve the international community's deep concerns over Iran's nuclear program," Meehan said. "Should this new government choose to engage substantially and seriously to meet its international obligations and find a peaceful solution to this issue, it will find a willing partner in the United States." 
 
 News organizations closely tied to Iran's ruling elite reported that in his letter, Obama proposed to "turn a new page" in relations, and held out a potential loosening of the economic sanctions that have crippled Iran's economy as part of an international effort to persuade Iran to give up nuclear development. 
 
 Obama urged Tehran to comply with the demands of the six world powers that have sought, unsuccessfully, to negotiate strict curbs on Iran's production of enriched uranium. Iran denies it is seeking to acquire a nuclear weapon. 
 
 Obama's letter was passed to Iranian officials in the final week of August, when Sultan Qaboos bin Said of Oman visited Tehran and met with Rouhani, supreme leader Ayatollah Ali Khamenei and others, the reports said. Oman is close to both countries, and Qaboos has been eager to act as a mediator, even offering to hold U.S.-Iran talks in his country. 
 
 Iran replied with an undisclosed message, according to reports on the Tabnak website and the Fars News Agency. Both are linked to the Iranian Revolutionary Guard Corps, the elite military organization at the heart of the Iranian government. 
 
 It's still unclear whether Tehran would give up uranium enrichment. It may be trying to drag out negotiations to avert more punishing economic sanctions while the country continues its drive to acquire nuclear capability, say U.S. officials and private analysts. Khamenei, the supreme leader, is considered extremely hostile to the United States. 
 
 But U.S. officials and experts say signs continue to accumulate that Iran intends to shift from a decade of stonewalling negotiations to at least a more open conversation. 
 
 Ray Takeyh, a former Obama administration advisor on Iran, said he believed the reported exchange of letters between Obama and Rouhani fit with other signals suggesting the two governments were serious about direct contact. 
 
 They "want to get together for talks, and perhaps for sustained ones," said Takeyh, an Iran specialist at the nonpartisan Council on Foreign Relations. 
 
 Takeyh said the White House outreach marked a shift from its position during international negotiations last year. At the time, U.S. officials pushed Iran to stop enriching uranium, ship its inventory of near-bomb-grade material out of the country, and close its deeply buried Fordow nuclear-enrichment facility. 
 
 If new talks take place, Takeyh said, the U.S. team must determine if Iran's attempted image makeover suggests a willingness to give ground, or if it is aimed at evading the kind of oversight the West has been demanding. 
 
 "Maybe the plan is to rebuild the image and make themselves look like a trustworthy member of the international community," he said. "Maybe the plan is to say: 'You can trust us with a nuclear program.'" 
 
 Obama's letter was probably made public by Iranian conservatives who are alarmed by Rouhani's possible overtures and want to build public opposition to any concessions to the United States, analysts said. Though there is powerful public pressure for sanctions relief, elements of the conservative elite remain strongly opposed to concessions. 
 
 Zarif this week denied a report about the letters carried in Al Hayat, an Arabic-language newspaper based in London. 
 
 Mehrzad Boroujerdi, an Iran specialist at Syracuse University, said Zarif's denial "was probably a sign that he doesn't want to be a target of the conservatives over this." But Boroujerdi said he, too, believed the reports of the letters were credible. 
 
 paul.richter@latimes.com 
 
 Special correspondent Ramin Mostaghim in Tehran and Times staff writer Shashank Bengali in Washington contributed to this report.
– Iran thinks it's poised to finally bury the hatchet with the US and strike a sanctions-ending nuclear deal—because officials believe President Obama offered that kind of rapprochement in his letter to newly-elected moderate Hasan Rouhani, a top Iranian adviser tells the New York Times. In Iran's reading, Obama offered face-to-face talks and promised to lift sanctions if Rouhani demonstrates a willingness to "keep your commitments and remove ambiguities." But Washington's interpretation is much less dramatic; an official says Obama wasn't necessarily promising leader-to-leader talks, or any specific sanction action. Rouhani wants to strike a quick deal in the next six months, before parliamentary elections begin. The normally politically powerful military is currently defanged, and Ayatollah Khamenei appears to be on board. In the meantime Rouhani's on a charm offensive. He wrote an op-ed in today's Washington Post in which he offers to "help facilitate dialogue between the Syrian government and the opposition," and promises an attempt to "move beyond impasses" with regard to Iran's nuclear program. He's on the interview circuit as well, with one coming up with Charlie Rose. Next week he'll give his first UN address, and for once the US may not walk out, the Post reports. Obama is speaking the same day, so the two might even meet.