The Unanswered Question

Iranian officials insist they just want to make fuel, and presented the Isfahan plant as a display of scientific prowess and peaceful endeavour. "You'll be able to see for yourselves the purity of our work, and you'll be able to tell the outside world the good news," Hossein Simorg, the spokesman for Iran's nuclear industry, promised before a guided tour of the facility.

As far as the much of the outside world is concerned, however, Isfahan is a nuclear flashpoint. Almost exactly two years ago, the seals on the tanks of uranium hexafluoride were broken in front of inspectors from the UN's International Atomic Energy Agency (IAEA), in an act of defiance by the Iranian government - a blunt signal Tehran was not going to halt its nuclear progress in return for the incentives Europe was offering. The order was given for uranium conversion to resume at Isfahan after a two-year gap.

That decision, in August 2005, marked the start of a crisis that has been steadily worsening ever since, to the point where Washington is said to be studying potential bombing targets, the Iranian leadership is spouting apocalyptic rhetoric, and Europe - once more caught in between - is scrambling to salvage a peaceful solution.

For the time being, the wires are back in place at Isfahan, along with two IAEA cameras that stare down from high perches on either side. But the degree of international control is tenuous at best. The very fact that the machinery is humming at Isfahan puts Iran in contravention of UN security council resolutions, calling for all work related to uranium enrichment to be suspended.

The tour given to foreign journalists was a show of openness which backfired when the government changed its mind at the last minute over what it was prepared to show. But the trip was also meant to send a clear message: that Iran has no intention of giving up any part of its nuclear endeavour, which it regards as entirely within its rights.

The Iranian government has dug in deep, convincing its population that mastery of uranium fuel production is synonymous with development and prosperity.

Before the Isfahan tour, a promotion film was screened showing the production of the first UF6 at the plant in 2004. The Iranian government also claims to have mastered the next step in the process, the engineering feat involved in spinning the UF6 in a high-speed centrifuge and separating out a variant, or isotope, of uranium, that is highly fissile - uranium-235. The work is being done at a centrifuge plant being built in Natanz, to the northeast of Isfahan.

Spinning the UF6 gas until it is up to 5% rich in U-235 produces nuclear fuel. Keep spinning until it is 90% enriched and you have the makings of a bomb.

That - combined with the fact that Iran omitted to tell the IAEA about Natanz until its existence was revealed by an opposition group in 2002 - lie at the roots of the global scepticism over Iran's programme.

But there is another huge question mark hanging over Isfahan and Natanz: why is the government in such a rush to enrich fuel, when it has no nuclear power plants in which to use it?

That's because their ultimate goal is not nuclear power for peaceful purposes but to develop nuclear weapons. The Iranians are intent upon doing so regardless of the consequences. Thus far, the consequences of their ongoing enrichment activities have been limited to strongly worded letters from the UN, and not much else. Having a couple of cameras and sensors watching only some of the work is insufficient. How much other work is going on in Natanz that is beyond the reach of the cameras and sensors?

How many centrifuges are operating and what is Iran going to do with the tens of thousands of centrifuges that they hope to have online in the next year or two? Once you have that many centrifuges operating, it is only a function of time and willpower to develop weapons grade materials.

These are ominous developments, and yet everyone is practically yawning at the situation.