The White House says Iran's talks with world powers on its nuclear program show "a level of seriousness and substance that we have not seen before."
Spokesman Jay Carney's comments Wednesday came a short while after talks in Geneva between Tehran and the five permanent members of the United Nations Security Council plus Germany ended with upbeat assessments from both sides. Further talks among the parties are set for November 7.
Despite Carney's appraisal, he warned reporters against expecting a "prompt breakthrough" in the nuclear talks. He referred to a history of mistrust between Tehran and the West that he described as "very deep," and said U.S. analysts will also study details of private Iranian proposals to end the nuclear stalemate.
The United States, Russia, China, France, Britain and Germany want Iran to prove it is not developing nuclear weapons, while Tehran is seeking relief from international sanctions aimed at forcing it to halt uranium enrichment activities.
Details of the latest Iranian proposals have not been made public. But Tehran has said it will not accept earlier demands from the so-called P5+1 grouping to suspend uranium enrichment or to ship stockpiles of processed uranium abroad.
Those demands also include Iran's compliance with a comprehensive verification regime - with unannounced checks by U.N. inspectors - and a reduction in Iran's level of uranium enrichment.
Earlier Wednesday, Iran's state-run news agency IRNA quoted Deputy Foreign Minister Abbas Araqchi as saying neither inspections nor uranium reduction issues have yet been addressed by Iranian negotiators. But other Iranian officials say they will be presented in the second and third phase of negotiations.
The Geneva talks are the first since relative moderate Hassan Rouhani was elected Iran's president in June. He promised to lead a diplomatic effort to get economic sanctions against Iran eased, but P5+1 officials have said Iran must prove its sincerity through concrete steps before that will happen.