Iran and six world powers have headed into nuclear talks at the United Nations with US officials tamping down expectations of any quick breakthrough.
The yesterday's meeting will mark the highest-level direct contact between the United States and Iran in six years as Secretary of State John Kerry comes face-to-face with Iranian Foreign Minister Javad Zarif.
It aims to pave the way for the first round of substantive negotiations on Iran's disputed nuclear program since April. That round is expected to be set for October in Geneva.
Iranian President Hassan Rouhani and Zarif, both in New York this week to attend the UN General Assembly, have said they are anxious to clinch an agreement quickly that could bring their country relief from punishing international sanctions.
But the US insists Rouhani must back up his calls for moderation with actions that verify Iran is not seeking to develop a nuclear weapon.
In Washington, the White House resisted putting a timeline on the nuclear negotiations.
"We're not expecting any breakthrough in this initial meeting," said White House spokesman Jay Carney. "But this is part of us testing the seriousness of the Iranians, who are obviously engaging in new overtures and showing new interest in trying to solve this very serious matter."
Encouraged by signs that Rouhani will adopt a more moderate stance than his predecessor Mahmoud Ahmadinejad, but skeptical that the country's all-powerful supreme leader will allow a change in course, President Barack Obama has directed Secretary of State John Kerry to lead a new outreach and explore possibilities for resolving the long-standing dispute.
Kerry predicted the meeting would be worthwhile. Asked what he would need to hear from the Iranians to show that they're serious, he said: "I'll let you know after they've been serious."
Rouhani's pronouncements at the UN have raised guarded hopes that progress might be possible. But they have also served as a reminder that the path to that progress will not be quick or easy.
In his speech to world leaders at the UN on Tuesday, he repeated Iran's long-standing demand that any nuclear agreement must recognise the country's right under international treaties to continue enriching uranium.
The US and its allies have long demanded a halt to enrichment, fearing Tehran could secretly build nuclear warheads. They have imposed sanctions over Iran's refusal to halt enrichment. Uranium enriched to low levels can be used as fuel for nuclear energy but at higher levels, it can be used to make a nuclear weapon.
Rouhani also insisted that any deal be contingent on all other nations declaring their nuclear programs, too, are solely for peaceful purposes alluding to the US and Israel. Those conditions underscored that there is still a large chasm to be bridged in negotiations.