Julian Borger writes: There will be no greater diplomatic prize in 2015 than a comprehensive nuclear deal with Iran. In its global significance, it would dwarf the US detente with Cuba, and not just because there are seven times more Iranians than Cubans. This deal will not be about cash machines in the Caribbean, but about nuclear proliferation in the most volatile region on Earth.

An agreement was supposed to have been reached by 24 November, but Iran and the west were too far apart to make the final leap. After nine months of bargaining, the intricate, multidimensional negotiation boiled down to two main obstacles: Iran’s long-term capacity to enrich uranium, and the speed and scale of sanctions relief.

Iran wants international recognition of its right not just to enrich, but to do so on an industrial scale. It wants to maintain its existing infrastructure of 10,000 centrifuges in operation and another 9,000 on standby, and it wants to be able to scale that capacity up many times.

The US and its allies say Tehran has no need for so much enriched uranium. Its one existing reactor is Russian-built, as are its planned reactors, so all of them come with Russian-supplied fuel as part of the contract. The fear is that industrial enrichment capacity would allow Iran to make a bomb’s-worth of weapons-grade uranium very quickly, if it decided it needed one – faster than the international community could react.

However, the west is currently not offering large-scale, immediate sanctions relief in return for such curbs on Iran’s activity. President Barack Obama can only temporarily suspend US congressional sanctions, and western states are prepared to reverse only some elements of UN security council sanctions. The best the west can offer upfront is a lifting of the EU oil embargo. [Continue reading…]