A Daily Briefing on Iran: Iran Ready to Ignore US Nuclear Countdown

The Observer discusses Paul Kenyon's documentary, 'Iran's Nuclear Secrets', is on BBC2 on Tuesday at 9pm: READ MORE

Paul Kenyon penetrates the Islamic republic's most secret installations as weapons inspectors grow wary and America presses the UN for action.

Across a landscape scattered with snow, we drove along silent roads, past pitted fields, until the first gun tower came into view. A whole line of them followed the contours of the mountainside. What they're defending lies beneath, a warren of rooms and tunnels the size of eight football pitches. It's home to Iran's most sensitive nuclear facility, Natanz.

Iran says it is part of a peaceful nuclear energy programme, but it has been built underground in case of air attacks. The Iranians' worries are not far fetched.

In the minibus, the United Nations' nuclear inspectors swap stories of Iran's reaction to their presence. 'Whatever we do, they're behind us trying to record our movements and it's disturbing,' says one of the most senior inspectors, Chris Charlier. 'It's all part of the game.'

Charlier is a Belgian nuclear scientist who has travelled the world inspecting nuclear installations for the International Atomic Energy Agency [IAEA], a nuclear arm of the UN. His conclusion on Iran is this: 'I believe they've tried to conceal their programme and their activities. And may be there are other things they're doing that we couldn't find. And that's why we're getting suspicious.'

The UN's suspicions about Iran went into overdrive 18 months ago. The Iranian Vice President, Reza Agazadeh, had just told the IAEA: 'Complete transparency of my country's nuclear activities is a serious commitment.' Then an Iranian opposition group operating outside the country tipped off the inspectors about Natanz, and other nuclear activities Iran had chosen not to declare.

Shortly afterwards, the inspectors asked for access to a nondescript warehouse in Tehran called The Kalaye Electric Company. At its heart were the highly-engineered centrifuges required to make nuclear fuel. The problem is, once a country has mastered enriching uranium for energy, it's not far off developing weapons grade uranium if it chooses. Which is why the UN inspectors wanted to test for nuclear particles. 'When they opened the door,' says Charlier, 'everything had been changed. There were new tiles to the roof, everything was brand new. It was still smelling of paint.'

More dramatic still was Lavizan, a suspected nuclear site on the outskirts of Tehran. It took two months for the inspectors to get access. When they arrived, the buildings, the equipment had gone. The satellite 'before and after' shot shows gleaming silver buildings being replaced by a triangle of rough brown earth.

Charlier is frank about what this pattern of behaviour means: 'The way they've been postponing, and trying to gain time, is suspicious. I don't think the IAEA has any facts to support the idea that they have a nuclear weapons programme, but the way that Iran has behaved in all those smaller issues has made the agency suspicious.'

The Americans are less cautious. 'There's no question that Iran is embarked on a project to acquire nuclear weapons,' says the assistant secretary of state for arms control, Stephen Rademaker. As in Iraq, there's no smoking gun but the circumstantial evidence leaves the US snorting in disbelief at anyone who doesn't share their conclusion.

Iran is unabashed by its apparent deceit. Its man at the IAEA is Syirous Naseri, a charismatic sharp-suited nuclear negotiator with an alligator grin, who appraised his handling of the American diplomats thus: 'If we talk to each other for five minutes we will have a fight.'

Naseri's position is that everything the inspectors have found is for nuclear energy. 'What we have is the right, an inalienable right to produce nuclear energy, not just to use but to produce nuclear energy,' he said.

He's right. Under the Nuclear Non-proliferation Treaty, each member state is supposed to share its peaceful nuclear technology with the rest. In theory that means that advanced countries, such as America, should be assisting the rest, Iran for example. The US sanctions imposed since the Islamic revolution, along with the West's traditional distrust of Iran, have put paid to that. Iran says that's why it has been so secretive. It went to the black market, built a multi-million pound nuclear programme and decided not to declare significant parts of it because, essentially, it knew everyone would be suspicious if it did. Simple. Nothing to worry about.

America doesn't buy it. It wants Iran referred to the UN Security Council as soon as possible. All that is preventing that from happening are the three European countries who believe there's still mileage in diplomacy. The UK, France and Germany have been in meetings with Naseri and his men for six months. The last round of talks was in London on Friday night. They persuaded the Iranians to temporarily suspend their nuclear enrichment programme.

But the Americans and Israelis are becoming impatient. There's a worry that these protracted negotiations with the Europeans are simply handing time to the Iranians to build a bomb. They have the centrifuges required - those they say are for making nuclear fuel - and they have the missile to launch them. So how long have we got before Iran goes nuclear? 'This issue is hotly debated among intelligent experts. We think it's measured in years, but not many years,' says Rademaker. Naseri is dismissive: 'Who are the Americans to say what we want to have, what we have, and what we should want? All they have done is made every effort that they could to deny us technology.'

With Iran determined to resume its nuclear enrichment programme and America equally determined that such a resumption will send it to the UN Security Council, this crisis seems certain not to be resolved by diplomacy alone.