By Paul Anderson
The Iranians say a first day of talks between their officials and Russian diplomats and experts on Iran's nuclear programme has ended satisfactorily.
Talks over Iran's nuclear activities with the IAEA have stalled
These centre on a proposal to transfer all of Iran's uranium enrichment programme to Russian territory.
It is backed by the European Union and the United States, which suspect Iran is trying to develop an atomic bomb. The Iranians strenuously deny this.
The talks come two days before Iran is due to resume its nuclear research.
'Satisfactory and suitable'
The Iranians insist on carrying out some enrichment in their country. Enriched uranium is used for nuclear power generation as well nuclear weapons.
Despite prompting condemnation from the West, Iran insists its nuclear research - which had been suspended - will resume as scheduled on Monday.
Talks designed to break the stalemate between the international atomic watchdog, the IAEA, and Iran have been fixed for later this month.
The outcome of the opening session of the latest effort to break the deadlock over Iran's nuclear programme was, according to one Iranian official, satisfactory and suitable.
There were no clues as to what that means precisely.
Officials on both sides are keeping tight-lipped. Clearly there is plenty to negotiate to iron out what the same official called ambiguities over the key issue: the proposal to transfer the enrichment of the uranium mined in Iran to Russia.
Secret for decades
The idea is to deny the Iranians the remotest chance to produce the highly enriched uranium needed for nuclear weapons.
Iran appears to accept the principle of a joint enrichment project, for power generation, on Russian soil.
But it insists on preserving the right to carry out some enrichment in Iran. For Western countries deeply suspicious of Iran's long term nuclear ambitions, that would defeat the purpose of establishing transparency in a nuclear programme which remained secret for decades.
As Western leaders and diplomats return from the new year holiday, they are discovering that this crisis has ballooned.
Iran announced this week it would resume its nuclear research. It has confirmed that will happen on schedule.
Washington talked tough in response, so too the EU, which warned that Iran's step could jeopardise the talks it is leading.
All the while, the day, this March, when the IAEA board of governors meets to discuss whether to refer Iran to the UN Security Council for possible sanctions, gets ever closer.