Iranian President Hasan Rouhani has said that his country will never seek a nuclear bomb.
He spoke to the American television network NBC News in Tehran just days before he is to make his first appearance as president on the world stage when he attends the United Nations General Assembly in New York.
US officials will be watching next week's visit closely for signs that Mr Rouhani will warm relations with the West and take a more moderate line in the next negotiations on Iran's disputed nuclear programme.
"We have never pursued or sought a nuclear bomb and we are not going to do so," Mr Rouhani said, according to an NBC translation of the interview. "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."
It was a claim Iran has made before, that its nuclear activities are purely peaceful. However, 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.
Mr Rouhani also addressed a question that many in the US have been asking - does he really have the power to make major decisions and concessions on the nuclear issue?
Iranian Supreme Leader Ayatollah Ali Khamenei is known to control all important matters of state, including nuclear. "In its nuclear programme, this government enters with full power and has complete authority," Mr Rouhani said. "We have sufficient political latitude to solve this problem."
Mr Rouhani is considered a relative moderate in Iran's hard-line clerical regime. He campaigned on a promise to seek relief from punishing US and Western sanctions that 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.
Turning to Syria, Mr Rouhani addressed US allegations that the Iranian-allied regime was behind a chemical weapons attack near Damascus last month. He said his country seeks peace and stability and the elimination of weapons of mass destruction in the entire region.
Asked whether President Barack Obama had looked weak by backing off a military strike on the Syrian regime, Mr Rouhani said: "We consider war a weakness. Any government that decides on war, we consider a weakness. And any government that decides on peace, we look on it with respect for peace."