Longer-Term Deal With Iran Faces Major Challenges

The Obama administration’s successful push for an accord that would temporarily freeze much of Iran’s nuclear program has cast a spotlight on the more formidable challenge it now confronts in trying to roll the program back.

For all of the drama of late-night make-or-break talks in Geneva, the deal that Secretary of State John Kerry and his negotiating partners announced early on Sunday was largely a holding action, meant to keep the Iranian nuclear program in check for six months while negotiators pursue a far tougher and more lasting agreement.

By itself, the interim pact does not foreclose either side’s main options or require many irreversible actions — which was why the two sides were able to come to terms on it. That was also a reason for the sharp negative reaction the deal elicited on Sunday from Israel, an American ally that is deeply suspicious of Iranian intentions.

Named the “Joint Plan of Action,” the four-page agreement specifies in terse language the steps Iran would initially take to constrain its nuclear effort, and the financial relief it would get from the United States and its partners.

A few technical details are left to footnotes. The agreement’s preamble says that a more comprehensive solution is the eventual goal, and the broad elements of that solution are given in bullet points on the final page. The agreement allows Iran to preserve most of its nuclear infrastructure, and along with it the ability to develop a nuclear device, while the United States keeps in place the core oil and banking sanctions it has imposed.

The questions that the United States and Iran need to grapple with in the next phase of their nuclear dialogue, if they want to overcome their long years of enmity, are more fundamental.

“Now the difficult part starts,” said Olli Heinonen, the former deputy director general of the International Atomic Energy Agency.

Even the planned duration of the comprehensive follow-up agreement is still up in the air. It will not be open-ended, but there is as yet no meeting of the minds on how many years it would be in effect. The interim agreement says only that it would be “for a period to be agreed upon.”

“The terms of the comprehensive agreement have yet to be defined, but it is suggested that that agreement will itself have an expiration date,” said Ray Takeyh, a former State Department official and a senior fellow at the Council on Foreign Relations. “It would be good if the comprehensive agreement was more final.”

Iran’s program to enrich uranium also needs to be dealt with in detail. The Obama administration has made clear that it is not prepared to concede at the start that Iran has a “right” to enrich uranium. But the interim deal, reflecting language proposed by the American delegation, says the follow-up agreement would provide for a “mutually defined enrichment program with practical limits and transparency.”

So the question appears to be not whether Iran will be allowed to continue enriching uranium, but rather what constraints the United States and its negotiating partners will insist on in return, and how large an enrichment program they are willing to tolerate. The interim accord makes clear that it must be consistent with “practical needs.” Iran and the United States are likely to have very different ideas of what those needs are.

“This, of course, will be one of the central issues in the negotiations for a comprehensive agreement,” said Gary Samore, who served as senior aide on nonproliferation issues on the National Security Council during the Obama administration and is now president of United Against Nuclear Iran, an organization that urges that strong sanctions be imposed on Iran until it further restricts its nuclear efforts.

“We will want very small and limited,” Mr. Samore said, referring to Iran’s enrichment efforts. “They want industrial scale.”

The negotiators will confront other difficult questions regarding elements of a comprehensive agreement that would be difficult to reverse. Will the underground Fordo enrichment plant have to be shut down? Will the heavy-water reactor that Iran is building near the town of Arak, which could produce plutonium for weapons, have to be dismantled or converted into a light-water reactor that is not useful for weapons development?

The interim deal “did not do enough to narrow down the limitations that will be in a final deal,” said David Albright, the president of the Institute for Science and International Security.

Hoping to reassure Prime Minister Benjamin Netanyahu of Israel, who called the easing of sanctions on Iran “a historic mistake,” President Obama told him that the United States would press for a comprehensive solution to the Iranian nuclear question in the months ahead.

Mr. Netanyahu on Monday dispatched a team headed by his national security adviser to the United States to discuss the final deal with Iran, which he said “must lead to one result: the dismantling of Iran’s nuclear capability.”

The diplomats who worked out the interim agreement left open the possibility that it might be extended beyond six months. The text of the deal says it is “renewable by mutual consent.”

Some analysts said that hammering out a comprehensive solution seems so onerous that there may never be an enduring accord but only a succession of partial agreements. Even if a more comprehensive agreement is never reached, experts say, a limited agreement can still be useful.

The interim deal includes improved verification, constraints on Iran’s installation of new centrifuges, and the requirement that Iran dilute its existing stock of uranium enriched to 20 percent, or else convert it to oxide, a less readily used form. Moreover, the cap imposed on Iran’s stockpile of uranium enriched to 5 percent would increase the time that Iran would need to make a dash for a bomb, adding several weeks or perhaps a month. “This may seem a small time,” Mr. Albright said. But because the interim deal also includes provisions that would make it easier to spot cheating swiftly, the added time “would be significant,” he said.

The United States successfully opposed Iran’s demand that it be allowed to continue installing components at the heavy-water plant at Arak. The interim pact also stipulates that Iran cannot test or produce fuel for that reactor or put it into operation. As it sought to strengthen the accord, the United States added a sweetener. As the talks progressed, the amount of oil revenue frozen in foreign banks that Iran would be allowed to retrieve was raised to $4.2 billion from $3.6 billion.

Mr. Kerry said on Sunday that he was as committed to “the really hard part,” obtaining a comprehensive follow-up agreement, “which would require enormous steps in terms of verification, transparency and accountability.” Speaking in London before a meeting with William Hague, the British foreign secretary, he said, “We will start today, literally, to continue the efforts out of Geneva and to press forward.”