What might derail the Iran nuclear deal?

Wednesday's draft agreement reached here to ship most of Iran's declared stockpile of low-enriched uranium (LEU) to Russia to be reprocessed – buying all sides a year of time – now awaits what Iran's negotiators term a "thoughtful review" in Tehran.

Iranian officials said the government would make a decision on the draft on Friday but Western negotiators are worried about backsliding, including possible attempts by Iran to send smaller amounts of nuclear material abroad than agreed to in the draft. French foreign ministry spokesman Bernard Valero said Thursday that for an agreement to stick, "The [entire amount of LEU] must leave Iran in one shipment before the end of the year." The current plan calls for Russia to enrich Iran's stockpile, and then deliver it to France for processing into the fuel rods that would run a small medical reactor in Tehran.

(For more on why Iran wants this medical reactor, click here.)

New sticking points, questions, and problems could easily emerge from Tehran, which recently admitted to another clandestine enrichment facility in the shrine city of Qom. If Ayatollah Ali Khamenei, the Islamic Republic's supreme leader, decides he wants to nix the idea there are many technical exceptions his negotiators could raise – ranging from the timing of the uranium shipments to the methods, or amounts, or the manner of the uranium's return for use, which Iran says it needs to fuel the medical reactor.

Put simply, there's no guarantee a deal negotiated in fits and starts this week, with few details offered, is done.

"The Obama people are right to keep this on a tight deadline," says David Albright, president of the Institute for Science and International Security in Washington. "If Iran doesn't meet the Friday deadline, that raises the question – 'Is this worth it?' They can object to sending all the LEU (low enriched uranium), or of not getting it all back at the same time. They are good at delaying."

A Western diplomat who has negotiated with Iran over its nuclear program in the past is skeptical that the concessions will be delivered precisely as contained in the draft. In his experience, Iranian negotiators have treated agreements not as final but as the launching pad for fresh negotiations. "They'll ship less uranium to Russia, or they'll break it up into smaller pieces over time, or they'll delay the start," he predicts.

On Thursday the deputy speaker of Iran's parliament said the negotiations in Vienna between Iran, France, the US and Russia put Iran in the untenable position of requesting help that the International Atomic Energy Agency (IAEA) should already provide, and cast it as a West vs. Iran issue: "They [the West] tell us: you give us your 3.5 percent enriched uranium and we will give you the fuel for the reactor. It is not acceptable to us," Mohammad Reza Bahonar said, adding that the IAEA was "obliged" to supply the fuel. While the decision is not Mr. Bahonar's to make, he's an influential hard-line politician and his comments mirror past statements made by Iranian President Mahmoud Amhadinejad and other leaders on the issue.'

Sticking points

Among technical sticking points, perhaps the main one is whether Iran will agree to send at least 2,600 pounds of uranium in one bulk shipment. France, backed by the US and Russia, made this a key requirement in Vienna. Iran explored sending the uranium in allotments – something that would allow its existing centrifuge's to supplement Iran's stockpile during a drawn out process.

Mr. Albright pointed to the recent history of delay. "The [Vienna] meeting was supposed to be in early October. Then it was Oct. 19; now they have until Friday. That could kick it to the weekend since Friday is a holy day. Then, we hear it is next week."

Wednesday's IAEA-brokered agreement with Iran has been kept strictly secret, and described as a "technical" document – throwing many of the details into the realm of speculation. Whether Russia will simply toss out Iran's uranium, preferring to reprocess some of its own less "contaminated" stockpiles is a question. So are the methods of the uranium's return: Iran, a state that is considered a violator of IAEA rules, may be pressed to only receive back its reprocessed uranium over time, in allotments gauged to its needs for running the medical reactor.

In that case France could make fuel rods for Tehran, but not return it all in bulk, where some of it could be used for the medical reactor, but some of which could be used in a secret military program.

A Vienna deal that involves nitty gritty negotiations between the US and Iran is hoped by the Obama administration to represent a first "good faith" step by Iran -- at a time when Israel has been threatening military action should Iran's nuclear program "break out" towards the capability to build a nuclear weapon.. It is also an example of Obama's effort to multi-lateralize diplomacy by sharing negotiating burdens with others – though the US-Iran talks on the sidelines of the meeting, under the auspices of IAEA chief Mohammed ElBaradei, were reportedly sought by Tehran as part of a process to normalize relations with the US.

US negotiators on Tuesday said privately they had given Iran every chance to say 'yes' to a deal – including offers of help to upgrade or improve the safety of the medical reactor, which was built with US government help when the country was still ruled by the Shah.

Critics argue Tehran doesn't want normalization but "legitimization" of its nuclear program.