Hillary Clinton, the US secretary of state, has warned that Iran's nuclear ambitions are putting the world at risk.
She told delegates at a nuclear Non-Proliferation Treaty (NPT) conference that Iran had violated its obligations and should be held to account.
Earlier, Mahmoud Ahmadinejad, Iran's president, accused states with nuclear weapons of threatening those who wanted to develop peaceful nuclear technology.
His comments prompted delegates from the US, the UK, and France to walk out.
The nuclear conference, currently held in New York, is not supposed to focus solely on concerns over Iran and its nuclear ambitions.
It is an event for states that are party to the Non-Proliferation Treaty to follow up or strengthen rules to ensure the system is working.
Have the NPT conferences become a platform to settle political accounts and an opportunity to lobby against adversaries?
Does the treaty help rid the world of nuclear weapons or does it advocate maintaining the status quo? And will Obama's nuclear undertakings help patch the gaps of the NPT?
Joining the programme are Mohammed Marandi, a professor of political science at Tehran University, Richard Weitz, the director of the Centre for Political Military Analysis at Hudson Institute, and Gareth Porter, a journalist for IPS News.
This episode of Inside Story aired from Wednesday, May 5, 2010.