Iranian President Hassan Rouhani told NBC News on Wednesday that his administration will never develop nuclear weapons and that he has full authority to make a deal with the West on the disputed atomic program.
In Rouhani's first interview with a U.S. news outlet since his election, he spoke to NBC News National and International correspondent/anchor Ann Curry at the presidential compound in Tehran. The interview will air on NBC Nightly News at 6:30 p.m. ET.
Rouhani spoke after a slew of signs that he is cautiously open to defrosting relations with the U.S., which were in deep freeze under the isolating leadership of his predecessor, the inflammatory Mahmoud Ahmedinejad.
Elected in June with just over 50 percent of the vote, he was the only non-conservative in a field of hard-liners. In his inaugural address, he spoke of engagement with the West to end sanctions over Iran's disputed nuclear program.
"The Iranian people voted 'yes' to moderation," he said in his speech.
Rouhani's appearance next Tuesday at the U.N. General Assembly — where western diplomats regularly stalked out of Ahmedinejad's fiery speeches — should provide more clues to just how moderate he is.
But analysts say there is reason to believe it's not all talk.
President Obama sent Rouhani a letter after the election — a rarity in itself — saying the the U.S. is "ready to resolve the nuclear issue in a way that allows Iran to demonstrate that its nuclear program is for exclusively peaceful purposes,'' White House spokesman Jay Carney said Wednesday.
The Scottish-educated Rouhani replied, expressing his views on "various subjects," an Iranian spokeswoman confirmed.
Rouhani and his foreign minister, Mohammad Javad Zarif, tweeted Rosh Hashanah well-wishes earlier this month, in stark contrast to the anti-Semitic vitriol of Ahmedinejad.
The head of Tehran's nuclear program said Monday that Rouhani has a "more full-fledged ... desire" to hash out the dispute with the West over its atomic program, expected to be the topic of talks later this year.
And Rouhani was quoted by his country's official news agency as saying he would accept any Syrian president elected by the people — without expressing unqualified support for the embattled Bashar Assad.
"Whoever Syrian citizens vote for to rule their country, we'll agree with it," Rouhani was quoted as telling commanders of the powerful Revolutionary Guard.
Experts say Rouhani's softer approach apparently has the support of Supreme Leader Ayatollah Ali Khamenei.
On Monday, the new president said the Revolutionary Guards — who report to Khamenei and have been accused of backing hard-liners — should stay out of politics. The next day, Khamenei was quoted on state TV as saying, "It is not necessary for the Guards to have activities in the political field."
Khamenei also spoke about the need for "flexibility.”
"I agree with what I years ago called heroic flexibility, because this is sometimes a very good and necessary move but with sticking to a basic condition," he was quoted as saying by the ISNA news agency.
"Sometimes a wrestler shows flexibility for technical reasons, but he doesn't forget who his opponent is and what his real goal is."
Despite the overtures, the tension between the U.S. and Iran — which cut diplomatic ties in 1980 after the hostage crisis — remains palpable.
After confirming Rouhani's letter exchange with Washington, a spokeswoman for the foreign ministry, Marzieh Afkham, criticized the tone of Obama's.
“Unfortunately, the U.S. administration is still adopting the language of threat while dealing with Iran,” Ms. Afkham said, according to the New York Times. “We have announced that this needs to change into the language of respect.”
Western diplomats remain wary, as well.
"The proof will be in the pudding," U.S. Energy Secretary Ernest Moniz said at the annual meeting of the International Atomic Energy Agency, where Iranian energy chief Ali Akbar Salehi pledged more cooperation.
"The words have to be followed by concrete action."
The Associated Press and Reuters contributed to this report.