GENEVA — Negotiators from Iran and six world powers convened Thursday as US officials signaled that the United States is prepared to offer Iran limited relief from economic sanctions if Tehran agrees to halt its nuclear program and reverse part of it.
Catherine Ashton, the foreign policy chief of the European Union, met Thursday morning with Mohammad Javad Zarif, the Iranian foreign minister, to discuss the arrangements for the first day of talks. Zarif touted the possibility of a breakthrough in remarks to reporters, perhaps calculating that it might encourage Western concessions.
“If everyone tries their best, we may have one,” he said. “We expect serious negotiations. It’s possible.”
A senior Obama administration was somewhat more cautious in comments Wednesday night, but also suggested that an initial understanding might be within reach.
“I do see the potential for the outlines of a first step,” the official said. “I do think it can be written on a piece of paper, probably more than one.”
The formal talks, which are to last two days, began at 11:20 a.m. with Zarif leading the Iranian delegation.
The world powers involved in the talks with Iran are known as the P5-plus-1 countries, so called because they include the permanent members of the UN Security Council — the United States, Britain, France, Russia and China — plus Germany. The US delegation is being led by Wendy R. Sherman, the undersecretary of state for political affairs.
Referring to the limited agreement the Obama administration is seeking, the administration official said the suspension of Iran’s nuclear efforts, perhaps for six months, would give negotiators time to pursue a comprehensive and far more challenging agreement.
“Put simply, what we’re looking for now is a first phase, a first step, an initial understanding that stops Iran’s nuclear program from moving forward for the first time in decades and that potentially rolls part of it back,” the official said.
The long-stymied talks with Iran were reenergized after Hassan Rouhani, the new Iranian president, took office in August and declared that he wanted to resolve longstanding concerns about the country’s nuclear program so that economic sanctions could be lifted.
But while the atmospherics in the talks have improved, administration officials are concerned that the window for negotiations might close if some way is not found to freeze Iran’s nuclear program. Some experts say it has advanced to the point that Iran has the technological capability to make a bomb.
Olli Heinonen, former deputy director general of the International Atomic Energy Agency, said in an interview that Iran had the technical know-how and sufficient quantities of uranium enriched to 20 percent purity to produce a crude nuclear explosive in two or three months if it decided to become a nuclear weapons state. It would take considerably longer for Iran to develop the means of delivering such an explosive by a ballistic missile, he added, but the nuclear threshold would have been crossed.
At the same time, US lawmakers have reacted to advances in Iran’s program by considering the imposition of even tougher economic sanctions, which Obama administration officials fear will harm the climate for negotiations.
“We’re looking for ways to put additional time on the clock,” said the administration official, who declined to be identified publicly under the administration’s diplomatic protocol for briefing reporters.
US officials would not provide details of the steps they wanted Iran to take to halt its nuclear program. But the administration official said such steps would cover the level of enrichment, Iran’s stockpiles of nuclear material, and the capabilities of Iran’s nuclear facilities, as well as verification. Just how long the suspension would last also remains to be negotiated, but six months is one time frame that has been discussed.
“In response to a first step agreed to by Iran that halts their program from advancing further, we are prepared to offer limited, targeted and reversible sanctions relief,” the administration official said, without specifying what sanctions might be eased.
US officials have said they want to keep core oil and banking sanctions in place until there is a comprehensive agreement.