Talks between Iran and six world powers over Tehran's nuclear ambitions ended Wednesday on a promising note when they released a joint statement for the first time, suggesting Iranian officials appear willing to negotiate.
The meeting in Geneva ended with a statement that described the talks as "substantive and forward-looking."
The tone of the negotiations appeared to signal a shift, a departure from the diplomatic standoff that prevailed under former Iranian President Mahmoud Ahmadinejad.
The latest discussions centered on a proposal put forth by Iran, which wants the six powers to recognize what it says is the peaceful nature of its nuclear energy pursuits.
Details, however, were scarce.
"We will be doing the negotiation in the negotiating room and not in the press," Iranian Foreign Minister Javad Zarif told reporters after the talks concluded.
Discussions were scheduled to resume November 7 and 8.
According to Iranian Deputy Foreign Minister Abbas Araqchi, who is taking a lead role in the negotiations, the sides could reach an agreement in as little as three to six months.
"The Iranian proposal was a new proposal with a level of seriousness and substance that we had not seen before," White House spokesman Jay Carney told reporters.
"No one should expect a breakthrough overnight," Carney said. "And these are complicated issues. They're technical issues. And as the President has said, the history of mistrust is very deep.
"The onus remains on Iran to come into compliance with its international obligations. And any deal must prove to the international community that Iran's program will be used for exclusively peaceful purposes," he said.
A senior U.S. administration official echoed Carney's cautious optimism.
"A positive outcome is not guaranteed," the official said, stressing at the same time that discussions were "intense, detailed, straightforward" and "candid."
The two-day talks brought together Iran's representatives and those from the so-called P5+1 -- the United States, Russia, China, France and Britain, all countries with permanent seats on the U.N. Security Council, plus Germany.
European Union foreign policy chief Catherine Ashton, who is leading the talks for the P5+1 bloc, called it a "very intensive and very important meeting."
She also declined to offer specifics but said they were the most detailed to date.
The joint statement built on a measured hope that was expressed after the first day of the talks.
"For the first time, we had very detailed technical discussions," a senior U.S. State Department official said. A spokesman for the EU's foreign policy chief called Iran's presentation "very useful."
Zarif, who is leading the Iranian delegation, said in a Facebook post Wednesday that their proposal outlined "a new view which emphasizes the need for pursuing a common goal by all players" and identified areas that must be agreed upon.
"This framework was welcomed as a new approach by the heads of the delegations. Of course we would like to see a new approach by the 5+1, as well," he said.
'Ball is in Iran's court'
Many in the West fear Iran is pursuing the development of a nuclear bomb, but Iran -- slapped with sanctions because of its program -- has always maintained that it is developing nuclear energy capabilities for peaceful purposes only.
Ashton's spokesman, Michael Mann, said Tuesday that the mood was one of "cautious optimism" but that the "ball is in Iran's court" to respond to the bloc's concerns.
The P5+1 bloc put forward its own proposals at a meeting with Iran in Kazakhstan in the spring, and these remain on the table, Mann told reporters.