Iran's recently installed President has said his country won't seek a nuclear bomb, and claimed - contrary to Western perception - he has the authority to make such decisions.
Hasan Rouhani spoke to the American TV station NBC in Tehran, ahead of his first appearance on the world stage when he attends the UN General Assembly in New York.
Described widely as a moderate, the Glasgow-educated former nuclear envoy was elected on a promise to ease tensions with the West and free the country from painful trade sanctions. The sanctions have slashed Iran's vital oil exports by more than half in the past two years, sent inflation soaring and severely undercut the value of its currency.
According to an NBC translation of the interview, Mr Rouhani said: "We have never pursued or sought a nuclear bomb and we are not going to do so.
"We have time and again said that under no circumstances would we seek any weapons of mass destruction, including nuclear weapons, nor will we ever."
That denial - along with the accompanying claim that Iran's uranium enrichment programme is for energy production - has been made before, including by Rouhani's predecessor, Mahmoud Ahmadinejad. It hasn't yet convinced UK or US administrations. The US and its allies suspect Iran is trying to develop a nuclear weapon, a feat some experts say the country might be able to accomplish as early as next year.
During past nuclear negotiations with the West, and despite the seemingly endless discord between the two sides, Rouhani became a respected and well-liked figure.
But Iran's Supreme Leader, Ayatollah Ali Khamenei, is known to control all important matters of state, with Rouhani not thought to have the clout to make decisions about nuclear policy. Rouhani denied this in the interview, saying: "In its nuclear programme, this government enters with full power and has complete authority. We have sufficient political latitude to solve this problem."
He also said he received a "positive and constructive" letter from US President Barack Obama upon his election in June. He said: "From my point of view, the tone of the letter was positive and constructive. It could be subtle and tiny steps for a very important future."
White House spokesman Jay Carney said there were no plans for Mr Obama to meet Mr Rouhani at the UN General Assembly.
He said: "I think it's fair to say that the President believes there is an opportunity for diplomacy when it comes to the issues that have presented challenges to the United States and our allies with regards to Iran.
"And we hope that the Iranian government takes advantage of this opportunity."