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As we've heard elsewhere in the program, the nuclear agreement reached with Iran over the weekend is a temporary deal with a six-month timeline. There are plenty of unresolved issues and possibly, tougher negotiations to come. NPR's Peter Kenyon has this look ahead.
PETER KENYON, BYLINE: Perhaps inevitably, how people judge this six-month freeze, and limited easing of sanctions, depends on whether they believe the next step - a comprehensive agreement - is possible or not. Secretary of State John Kerry made the case for nuclear diplomacy in Geneva.
SECRETARY JOHN KERRY: If this first step leads to what is our ultimate goal, which is a comprehensive agreement, that will make the world safer. The next phase - let me be clear - will be even more difficult, and we need to be honest about it. But it will also be even more consequential.
KENYON: More consequential and as of now, all the more urgent. As Iranian leaders point out, the enrichment of uranium above 5 percent is being suspended, not scrapped. And while Iran won't be adding new centrifuges, or finishing work on a heavy water reactor at Arak over the next six months, neither of those projects will be mothballed.
Likewise, the international side is giving Iran a relatively small increase in revenue as some sanctions are eased, but they can also be put back in place quickly and even increased, as Congress has repeatedly promised. In essence, both sides have called a timeout from the old status quo of increasing sanctions versus an increasingly dangerous Iranian nuclear program, to see if it's possible to prove that Iran means what it says when it denies any desire for nuclear weapons.
Critics, including Israeli leaders, tend to focus on the downside risk. If the long-term talks collapse, will Tehran emerge closer to acquiring a bomb? If the interim agreement holds, experts say the answer should be no. The breakout time - the time it might take Iran to dash toward a stockpile of weapons-grade uranium - would be lengthened by about a month or two, meaning U.N. inspectors on the ground almost daily would have more opportunity to detect such a move than they have today.
But what if Iran has a secret nuclear facility? It wouldn't be the first time. Analyst Ali Vaez, at the International Crisis Group, says it's important that the next stage include more tangible steps to keep the diplomatic momentum going.
ALI VAEZ: And I think, actually, the high tempo of diplomacy that we have witnessed over the past few weeks is going to be maintained, and the two sides will try to back up the first step with additional interim measures because otherwise, it would be very hard to protect the process from criticism.
KENYON: One such step could be for Iran to respond to concerns raised in U.N. Security Council resolutions on Iran's nuclear program. Much remains to be done, including establishing how long any comprehensive agreement might last. But right now, Iranians who have long wished their country would move beyond the confrontational approach favored by former President Mahmoud Ahmadinejad, are savoring a hopeful moment. Trita Parsi, head of the National Iranian American Council, can't help thinking about what might happen if things continue unexpectedly to go well.
TRITA PARSI: Because now, this more constructive approach has yielded a better result for the Iranians than the confrontational approach of Ahmadinejad. That will have repercussions for domestic policy, human rights, and the movement towards democracy as well.
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KENYON: Analysts say such change remains uncertain, at best. But if the cheering crowds that greeted Iran's nuclear negotiators on their return to Tehran are any indication, Iranians seem more than happy to push the hard-liners - for the moment, at least - off center stage.
Peter Kenyon, NPR News, Istanbul. Transcript provided by NPR, Copyright NPR.