So, Iran has tentatively struck a deal that will involve shipping most of its known supply of low-enriched uranium overseas. But forget the hype about a grand bargain with Tehran. This is a modest step forward, at best.

"We are buying something like seven to 10 months," a nameless insider told the Christian Science Monitor. And even that short timeline might be an overstatement.

There are at least 50 cascades of 164 centrifuges each now installed at the Natanz enrichment facility, although many were still under vacuum in August. According to Alexander Glaser, a single cascade of 164 IR-1 centrifuges could be expected to produce up to 113 kilograms of 3.5 percent low-enriched uranium (LEU) a year. Discount the efficiency of operations somewhat (Geoff Forden suggests 85 percent based on past performance at Natanz), and Iran could recreate 1,200 kilograms of LEU in a shade over four months using 36 cascades. With 54 cascades going, it would take less than three months.

I'm not predicting that Iran will go flat-out to recreate its present LEU stockpile, but I would expect them to keep enriching at some rate. That rate may vary; having discovered what sort of safeguarded LEU stockpile the West, Russia and China are prepared to tolerate, the Iranian side might seek to influence the pace and urgency of future talks by the pace of operations at Natanz.

Also, we cannot really expect this narrow, technical transaction to bring about a sea change in relations. For a preview of how the Iranians are likely to sell it to their own public, consider this item from the IRIB news agency, which couches the uranium export as an Iranian demand:

The Islamic Republic of Iran demands that up to %5 of enrichment for Tehran's research reactor to be done in Iran and then be sent to one of the three countries (Russia, France or America) for more enrichment.

This bargain, we can be sure, will be touted in Tehran as a victory — meaning, of course, a defeat for the other side. That's the political context in which these talks operate. Future rounds probably won't be much different. Actually reaching a grand bargain on all the issues dividing Iran and the West would deprive the Islamic revolution of any substance; forget it. These are nuclear talks, with perhaps some excursions into hostage negotiations. (There is precedent for goodwill gestures.) The real challenge before the United States and the other major powers is to decide what they really want most. Zero enrichment and reprocessing in Iran? Significantly strengthened safeguards? And then, there's deciding how to get there.

*Joshua Pollack is a columnist at the Bulletin of the Atomic Scientists and blogs about nuclear issues at ArmsControlWonk.com, where this post originally appeared. This is his first contribution to Danger Room. *

[Photo: President.Ir]

ALSO: