In Iran Talks, Nuclear Gains Offer Challenge

With thousands of advanced centrifuges spinning and Iranian engineers working on a plant that will produce plutonium — which also can be used in a weapon — Iran’s program presents a daunting challenge for negotiators determined to roll back its nuclear activities.

Both sides enter the nuclear talks that begin here Tuesday with inherent strengths and weaknesses. Iran walks in with a nuclear program that cannot easily be turned back, while the West has imposed sanctions that have crippled the Iranian economy.

And if Iran is going to maintain the right to enrich uranium to even low levels, as it continues to insists it must, the West would surely demand highly intrusive inspections — far more than Iran has tolerated in the past. How these matters are resolved will go far in deciding the success or failure of the talks.

In 2003, Iran had a relative handful of relatively unsophisticated centrifuges. Today, it has at least 19,000, and 1,000 of those are highly advanced. Those have been installed but are not yet being used to enrich uranium

That is more than enough, experts say, to transform low-enriched uranium from the 3 percent to 5 percent range to weapons grade in a few months — the so-called breakout that is unacceptable to the West and Israel.

“Ending production of 20 percent enriched uranium is not sufficient to prevent breakout, because Iran can produce nuclear weapons using low-enriched uranium and a large number of centrifuge machines,” said Gary Samore, a senior aide on nonproliferation on the National Security Council in President Obama’s first term.

In addition, Tehran is nearing completion of a heavy-water reactor that would be capable of producing plutonium for nuclear bombs, another factor that Western experts say argues for far broader constraints.

The talks in Geneva are the first between Iran and the United States and five other world powers since the election of Iran’s new president, Hassan Rouhani, who took office in August and has made a priority of easing the crippling sanctions imposed on Iran over its nuclear activities.

A series of conciliatory messages and speeches from Mr. Rouhani and other Iranian officials — capped by a phone call to the Iranian president from Mr. Obama last month — has helped foster the most promising atmosphere for negotiations since 2003, when Mr. Rouhani was Tehran’s lead nuclear negotiator.

A senior American official said on Monday that the United States was heartened by the change of tone in Tehran and believed that Mr. Rouhani’s election signals a sincere intention by Iran to chart “a more moderate course.”

But the official also said that the United States and its partners were still waiting to see if Iran would take concrete steps to constrain the pace and scope of its nuclear program, limit its growing stockpile of enriched uranium and be more open about its nuclear activities.

“We are going to make judgments based on the actions of the Iranian government, not simply its words, although we appreciate the change in its tone,” the official said.

As hopeful as the Obama administration may be, a number of issues may prove contentious in the P5-plus-1 talks, involving the five permanent members of the United Nations Security Council — Britain, China, France, Russia and the United States — and Germany.

In hinting that they will accept some constraints on their nuclear program, for example, the Iranians have stressed that they want quick reciprocal steps to ease sanctions.