Six world powers — the United States, Russia, China, France, Britain and Germany — began formal talks with Iran on its nuclear program in Geneva on Tuesday with a presentation from Tehran that the Iranian delegation and a European Union spokesman said was well received.
Saying that Iran no longer wanted to "walk in the dark” of international isolation, Deputy Foreign Minister Abbas Araqchi told reporters that "the first reactions were good" to a blueprint laid out by Iran's Foreign Minister Javad Zarif to end the impasse over Tehran's nuclear program.
"We think that the proposal we have made has the capacity to make a breakthrough," Araqchi said.
A Geneva-based E.U. spokesman described Iran's initial proposal, which took the form of an hour-long PowerPoint presentation delivered on Tuesday morning, as "very useful" and added that "very technical discussions" were set to continue in the afternoon.
The meeting, which will extend through Wednesday, is the first such round of talks among the group since the election of reformist Iranian President Hassan Rouhani in June.
The meeting of the P5+1 — the five permanent members of the U.N. Security Council and Germany — follows recent signals from Iran that it wants to thaw relations with the U.S. The leaders of both countries have underscored the desirability of a deal on Iran's nuclear program.
Following Tuesday's session, the U.S. and Iran held a bilateral meeting on the sidelines that a State Department official called "useful."
Araqchi said the details of Iran's proposal, which Iran named "An End to the Unnecessary Crisis and a Beginning for Fresh Horizons" remained confidential, but he called the plan "completely realistic, balanced and logical."
Iranian state TV reported that Tehran offered to discuss uranium enrichment levels and proposed adopting the additional protocols of the U.N.'s nuclear treaty that would open the country's nuclear facilities up to wider inspection and monitoring if the West agreed to recognize Iran's right to enrich uranium.
A U.S. State Department official who was not authorized to disclose details of the meetings said that the afternoon session gave the six powers opportunity to probe for further details on Iran's plan.
Although Rouhani said in New York last month that he wanted a deal with the P5+1 within three to six months, Foreign Minister Zarif played down expectations that an agreement would be reached this week.
"Tomorrow is the start of a difficult and relatively time-consuming way forward," he said on his Facebook page prior to the meeting. "I am hopeful that by Wednesday we can reach agreement on a road map to find a path towards resolution.
"But even with the goodwill of the other side, to reach agreement on details and start implementation will likely require another meeting at ministerial level," he said.
The U.S. official said the Obama administration was encouraged that Rouhani, who avoids the strident anti-Western and anti-Israeli rhetoric of his predecessor Mahmoud Ahmadinejad, had a mandate to "pursue a more moderate course."
But Tehran must be put to the test, the official said.
"That is what we will be doing over the coming days," the official said, adding "No one is naive about the challenges we face about pursuing the diplomatic path."
"We need to see concrete verifiable actions," the official said. "We go into these meetings clear-eyed that we have very, very, very difficult work to do.
"We are going to make judgments based on actions of the Iranian government, not simply its words, although we appreciate the change in its tone," the official said.
Backing up those words, 10 Democratic and Republican U.S. senators said Monday they were open to suspending the implementation of new U.S. sanctions, but only if Tehran took significant steps to slow its nuclear program.
The U.S. official said Washington had three priorities regarding Iranian assurances: Tehran must take steps on the production of nuclear and related material, ensure transparency of the nuclear program and take steps regarding its stockpile of nuclear material.
In the past, the six powers have demanded, among other things, that Iran halt uranium enrichment, particularly to 20 percent fissile purity; move stockpiles of enriched uranium out of the country, and close the Fordow enrichment plant, buried inside a mountain south of Tehran.
On Sunday, Iran rejected the demand that it send enriched uranium abroad but signaled flexibility on other issues.
Meanwhile, Israel, the Middle East's only state with a presumed nuclear arsenal, has warned the West not to ease sanctions before Tehran has addressed fears about its nuclear ambitions.
Doing so would be a "historic mistake," Israeli Prime Minister Benjamin Netanyahu warned Monday, a day before the Geneva talks.
"It would be an historic mistake to ease up on the pressure now, a moment before the sanctions achieve their objective, and particularly now, we must not give up on them but continue the pressure," Netanyahu said at the opening of the Israeli parliament's winter session.
Al Jazeera and wire services