Iran’s President Mahmoud Ahmadinejad made the point on his official website on Sunday, saying: “Today if they guarantee that they will provide 20 percent enriched fuel for the Iranian reactors, we won’t have any problem.” Ahmadinejad has little influence on nuclear policy, but the timing was significant.

Mr. Jalili’s deputy Ali Bagheri, for the first time in three rounds of negotiations this year, briefed journalists at the end of the first day of talks.

Apparently feeling the need to state Iran’s case, he said Iran responded to P5+1 concerns with “lengthy and detailed” discussions about how “clear, reciprocal steps” needed to be taken by each side, which could result in a “very serious achievement.”

Top priority for Iran, said Mr. Bagheri, is “the right to enrich (uranium) as a responsible member state of the NPT,” or Nuclear Non-Proliferation Treaty. The Iranians, he said, also needed confidence building measures and “emphasized the mechanism which could be implemented in order to attain the confidence of the Iranian people.”

Jalili’s presentation “caught the attention of the other side,” said Bagheri, in “constructive and serious” talks.

Jalili told the P5+1 that the referral of Iran’s nuclear dossier to the United Nations Security Council was “illegal.” Since 2006, the council has imposed half a dozen resolutions that require a suspension of enrichment, while Iran resolves questions about past weapons-related work.

Even as the talks got under way in Moscow, Iran’s supreme religious leader Ayatollah Ali Khamenei, speaking in Tehran, warned world powers to “learn from the unsuccessful experience of confronting the Iranian nation and they should know that arrogance and irrelevant expectations ... won’t work.”

Ayatollah Khamenei’s web page used a headline that began: “Enemies need to learn lessons ...”

On the eve of the Moscow talks, a Western official said the P5+1 was ready to take “reciprocal steps in exchange for verifiable Iranian actions.”

The P5+1 proposal put forward in Baghdad has not changed, and includes likely deal-breakers for the Iranians such as suspension of all enrichment – which Iran for years has turned into a point of national pride – and shutting down a deeply buried enrichment facility that is closely monitored by UN nuclear inspectors.

“As we have said, Iran has a right to peaceful nuclear energy under the NPT, but it must first meet its international obligations,” the Western official said, indirectly referring to the UN resolutions that require suspending all levels of enrichment. “If Iran remains unwilling to take the opportunities these talks present, it will face continuing and intensified pressure and isolation.”

Iranian officials say they won’t cross their own red line and halt enrichment, as they once did from 2003 to 2005, only to see little return from their European interlocutors at the time.

The dispute over enrichment, which Iran began again in 2005 and has continued ever since, could derail the Moscow talks tomorrow. Western powers are concerned that Iran has stockpiled enough enriched uranium for four to five nuclear bombs, if enriched to higher levels.

“This is among the first or second most important thing for us,” says the Iranian diplomat. “Their (P5+1 priority) is any diversion of nuclear material for military purposes. Ours is recognition of our right to enrich.”