US Secretary of State John Kerry is heading to Geneva to join negotiations about Iran's nuclear programme, the State Department announced today, raising expectations that a deal to curb Tehran's nuclear program could be in the works.
State Department spokeswoman Jen Psaki said Mr Kerry would arrive early tomorrow, joining Russian Foreign Minister Sergey Lavrov.
They will lend weight to negotiations aimed at beginning a rollback of Iran's nuclear programme in exchange for easing US and international sanctions.
Negotiators have been working since Wednesday to find language acceptable to Iran and its six negotiating partners - the US, Russia, China, France, Britain and Germany.
As negotiations moved into the evening, a diplomat in Geneva for the talks said some progress was being made on a key sticking point - Iran's claim to a right to produce nuclear fuel.
Iranian foreign minister Mohammad Javad Zarif and Catherine Ashton, the European Union's top diplomat, have met repeatedly since Wednesday trying to resolve that and other differences.
The last round of talks between Iran and the six world powers ended November 10 with no deal even after Mr Kerry, Mr Lavrov, the foreign ministers of Britain, France and Germany and a Chinese deputy foreign minister flew in and attempted to bridge differences.
Mr Zarif and Baroness Ashton met briefly today for talks that Iran's official Irna news agency described as "complicated and tough."
It quoted Iranian deputy foreign minister Abbas Araghchi in Geneva as saying that Iran's right to uranium enrichment must be part of any deal.
Iran says it is enriching only for reactor fuel, medical uses and research. But the technology can also produce nuclear warhead material.
Mr Zarif last weekend indicated that Iran is ready to sign a deal that does not expressly state Iran's right to enrich, raising hopes that a deal could be sealed at the current Geneva round.
On Wednesday, however, Iran's supreme leader, Ayatollah Ali Khamenei, said his country would never compromise on "red lines".
Since then Tehran has reverted to its original line - that the six powers must recognise this activity as Iran's right under the nuclear Nonproliferation Treaty despite strong opposition by Israel and within the US Congress.
A senior Iranian negotiator said that the Iranian claim did not need to be explicitly recognised in any initial deal, despite Mr Khamenei's comment. He did suggest, however, that language on that point remained contentious, along with other differences.
The diplomat said work was proceeding on a compromise along the lines of what the Iranian negotiator said - avoiding a direct reference to any country's right to enrich but still giving enough leeway for Iran to accept it.