Speaking to reporters shortly after the talks ended in Switzerland, Clinton struck a cautious tone and said it remained to be seen whether the Iranians would act decisively to address concerns about their intentions.
"There were a number of issues raised, put on the table, and now we have to wait and see how quickly -- and whether -- Iran responds," she said. She did not specify the issues or speak in detail about how Iran should respond.
Clinton said she got a rundown on the substance of the talks in a telephone call from William Burns, who represented the Obama administration. The other countries involved were Russia, China, Britain, France and Germany.
"It was a productive day, but the proof of that has not yet come to fruition, so we'll wait and continue to press our point of view and see what Iran decides to do," Clinton said.
Asked whether the U.S. strategy of offering more direct dialogue with Iran was paying off, she said more than gestures and discussions are required.
"I will count it as a positive sign when it moves from gestures and engagements to actions and results," she said. "That's a necessary pathway and I think we're on it. We've always said we would engage. But we're not talking for the sake of talking," she said, adding, "Today's meeting opened the door, but let's see what happens."
Department spokesman Ian C. Kelly said later that during a session with the Iranian negotiator, Burns raised human rights issues as well as U.S. concerns about three Americans arrested in Iran in July for illegally entering the country from Iraq.
Burns told the Iranian that the Americans' cases were "an urgent matter and must be resolved as soon as possible."