The Economist, May 17th, 2014
Excerpts
Rather than to agree to have Fordow permanently shut down, the Iranians are offering to turn it into a small research-and-development site, moving the centrifuges from there to be stored at Natanz, Iran’s main enrichment center.
Neither that nor the modification of Arak would be sufficient without a greatly enhanced inspection regime.  The agency is l not happy about the cooperation it is getting in its investigation of the “possible military dimensions” of Iran’s past nuclear program. It complained this week that it still had not been able to get access to Parchin, a military site where it suspects high-precision detonators designed to initiate the chain reaction for a nuclear-implosion device have been tested.  That still remains a pretty big if. Gary Samore, who was Barack Obama’s senior adviser on arms control for four years, notes three big remaining obstacles: agreeing on the extent of Iran’s capacity to enrich uranium and the kind of research it can do; the length of time an agreement would cover; and the way in which sanctions are unwound.
The gap between Western and Iranian negotiators on all three is wide. To sell a deal to a skeptical Congress, already uncomfortable with conceding what Iran insists is its right under the NPT to enrich, only a very low number of centrifuges will be acceptable; people close to the talks suggest between 3,000-4,000 of the older IR-1 centrifuges at most. But Iran wants to keep all 19,000 of the centrifuges it has already deployed and to be able to move up to 50,000 in a few years or substitute IR-1s with newer IR-2ms that are six times more efficient. It would also deem any curb on its nuclear R&D to be insulting.
The requirement for Mr. Obama’s team, says Mr. Samore, is to be able to say that the breakout period (the time Iran needs to enrich enough uranium for just one nuclear device after throwing out the IAEA inspectors) is at least a year, compared with about two months now. Though a crude measure, everyone understands it. Mr. Samore thinks it would be politically impossible in America to sell anything less.
The West is looking for an accord with Iran to last between ten and 20 years. Iran is talking about five years as an absolute maximum. Finally, the Americans and Iranians differ over the sequencing of sanctions relief. The best Mr. Obama can offer is to use his “national-security waiver” to suspend sanctions, perhaps indefinitely. But he cannot expunge the legislation without Congress’s support.