There is a chance that Iran is running out of yellow cake uranium and the western powers are working frantically behind the scenes to try and stop them from getting any more.

Iran's original supply of yellowcake was purchased by the Shah back in the 1970's as part of their internationally monitored civilian nuke program. Since it takes several tons of yellowcake to make a pound of U-238, Tehran's original supply should be near exhaustion if you take into account how much  U-238 they have (a guestimate by our intel people as well as the IAEA) and how much they probably ruined in initial attempts at isotope separation.

The Times Online has the story :

It was shortly before Christmas that diplomats at Britain’s sleek new embassy on Kosmonavtov Street in the Kazakh capital of Astana received a confidential and urgent request. Iran, officials back in Whitehall advised, was believed to be close to running out of its stockpiles of yellow cake — a powdered form of uranium ore.

There were concerns that Tehran could be seeking fresh supplies to support its nuclear programme at a critical juncture — just months before intelligence experts expected it to have accumulated enough enriched material for a bomb. British officials were to urge Kazakhstan, one of the world’s biggest producers, to ignore any possible approaches to obtain imports.

The request, news of which emerged after an international investigation by The Times, was part of a drive by six countries — Britain, the US, France, Germany, Australia and Canada — to choke off supplies of uranium to Iran. It is a move that, while unlikely to cripple any effort to develop a bomb, would blunt its ambitions and help to contain the threat, authoritative sources said.

Kazakhstan, with 15 per cent of the world’s deposits, is an increasingly important player in the global uranium trade and has set a target this year to become the world’s largest producer.

Uzbekistan, where British officials are involved in a similar lobbying exercise, also has large deposits and was a leading supplier for weapons-grade material during Soviet times.

Overtures have also been made to the Congo and Niger - two other countries where Iran could also resupply.

The Congo may be the key. Given the general chaos in that country and lax government control, it is perhaps more possible there than anywhere else that a third party acting on behalf of the mullahs could acquire at least some uranum hex.

But with western governmetns alerted to the possibility, it will take a lot of subterfuge by Iran to acquire uranium hex in quantities that would allow it to continue it nuke program in the future. Both western governments and the IAEA believe Iran has enough uranium hex on hand to finish the job of enriching a quantity of the material in order to construct at least one nuke.