As President Mahmoud Ahmadinejad loads nuclear fuel rods into the Tehran Research Reactor, experts say Iran does have the technology to make a nuclear weapon, but lacks the political will - for now.

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Iran unveiled new centrifuges able to enrich uranium much faster, a move sure to intensify suspicions that it is seeking to make atomic bombs.

"The era of bullying nations has past. The arrogant powers cannot monopolise nuclear technology. They tried to prevent us by issuing sanctions and resolutions but failed," Mr Ahmadinejad said in a live television broadcast.

"Our nuclear path will continue."

He added that the "fourth generation" of centrifuge would be able to refine uranium three times as fast as previously.

The broadcast demonstration is also being seen as a show of defiance by Tehran, which appears to have make significant progress in its nuclear ambitions despite sanctions imposed on it by the West.

American officials were quick to dismiss today's developments. State Department spokeswoman Victoria Nuland told reporters that Tehran's reported advances were: "not terribly new and not terribly impressive."

Speaking on Channel 4 News, Mark Fitzpatrick, the Director of the Non-Proliferation and Disarmament Programme at the International Institute for Strategic Studies, said that although it had hyped up its nuclear progress, Iran does have the technology to make a nuclear weapon, but he stressed that for Iran to do so would be a political decision with devastating consequences:

"Iran has enough low-enriched material for four weapons-worth - if further enriched. But if they went to further enrich it, the inspectors would find out, the world would know and we would be at war. I don't think Iran will take that step - at least not in this year, but it's getting closer."

British nuclear consultant John Large, has warned that there is an increased risk of a major nuclear disaster as a consequence of the country's scientific isolation. Tehran's infrastructure is old and rudimentary, and it has been working on its nuclear programme for a long time without assistance from more nuclear advanced nations:

"Because Iran has not been given the expertise of the international nuclear community, because its scientists have not been allowed to attend conferences and because its components are so old, yes, there is a big risk of the plant being unstable," he said.

Independent nuclear engineer John Large, analyses the implications of Iran's breathrough moment for Channel 4 News.

How has Iran got to this stage?


"Nuclear technology is very established, its been around since the 40s. As such, its difficult to contain knowledge about it. So while the International community has found it impossible to stop knowledge of how to run a nuclear programme, it has tried to stop certain countries from producing the material needed to start up such a programme. Through the IAEA, it tried to make those nations who wanted to start up a programme only able to do so by producing everything it needed internally. But where it has failed is where it hasn’t stopped countries like Iran taking a shopping basket over a number of years and going to other countries like Pakistan, Malaysia, Argentina and Brazil and getting the necessary components before having a recognisable nuclear programme."


How advanced are their weapons likely to be?

There are hints in Iran’s nuclear developments in the last few years that it is not looking forward or sideways with its ambitions, but backwards. In other words, it is not trying to emulate the newest forms of the technology, but replicating old versions. It looks like they are trying to create polonium berrylium – (often used as a trigger for nuclear weapons) which was first used in the late 1940s.

How do we know Iran is not building a civil nuclear programme?

For a start they don’t need a civil nuclear programme to power anything. Secondly, for the type and amounts of material they are known to be using and developing, that is way more than would be required for a civil programme as opposed to making nuclear weapons. All the indicators point to their ambitions to build weapons.

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Heightened tension

Meanwhile, Iran's oil ministry denied that it had cut off oil exports to six EU states even though this had been reported in a broadcast by Iranian state media.

"We deny this report ... If such a decision is made, it will be announced by Iran's Supreme National Security Council," a spokesman for the ministry said.

Earlier on Wednesday, Iran's English language Press TV said Tehran had halted oil deliveries to France, Portugal, Italy, Greece, Netherlands and Spain - its biggest EU customers - in retaliation for an EU ban on Iranian crude due to take effect in July.

The US maintained a close presence in the region in the form of its aircraft carrier, the SS Abraham Lincoln, which sailed through the Strait of Hormuz and close to the Iranian shoreline on Tuesday.

The Strait is used for a third of the world's seaborne oil trade, and last month, Tehran threatened to close it in retaliation to further sanctions placed on it by the international community, which objects to its nuclear programme.

The show of force is the latest in a string of events that has led observers to voice concerns that posturing may soon evolve into war.

Ahmadinejad - Reuters

In January, defence analyst Anthony Tucker-Jones, predicted in an article for Channel 4 News that Iran's progress in its nuclear ambitions would significantly intensify relations between Tehran and the US and Israel. He wrote: "No international consensus is likely (on Iran's nuclear activities) and America and Israel would have to act unilaterally."

And Israel this week accused Tehran of escalating tensions after the capture of two Iranian nationals in Bangkok following a bungled series of explosions. The finger was pointed in the same direction last week, too, when an Israeli diplomat's wife and driver were wounded in New Delhi when a bomb stuck to their vehicle detonated, and another device was defused on an Israeli Embassy car in Tbilisi, Georgia.

The events took place a matter of weeks after an Iranian nuclear scientist had been killed by a bomb placed on his car by a motorcyclist in Tehran, the fourth such attack on nuclear experts in the country in two years. In each of those cases, Tehran accused Israel of being responsible. In January, Lieutenant General Benny Gantz, the Chief of the Israeli General Staff, reportedly told an Israeli parliamentary panel that this would be a "critical year" for Iran, partly due to "things that happen to it unnaturally."

On Wednesday the Israeli Prime Minister Binyamin Netanyahu told the Knesset: "the world must denounce Iran's terrorist activity and mark red lines on the Iranian nuclear programme."

Professor Malcolm Chalmers of the Royal United Services Institute warned that the current state of heightened tension carries its own dangers: "This is not war, but it's beginning to look very much like an indirect version of war, and when you get into a war-like situation, it is harder to make concessions - on either side."