AUDIE CORNISH, HOST:
Diplomats from the U.S., Russia and other world powers wrapped up a meeting with Iran today about its nuclear program. The deal they're trying to hammer out is this: Iran modifies its program so that it can't produce nuclear weapons. And in exchange, Western powers lift sanctions. Negotiators released a joint statement calling the talks substantive and useful. A senior U.S. official said it is going to take some hard work to reach an agreement. The talks will resume on April 7th. NPR's Peter Kenyon has been following the negotiations and joins us from Vienna. And, Peter, it seems as though more is known about what was discussed this time because Iranian officials listed four issues that were on the table. What more can you tell us?
PETER KENYON, BYLINE: Well, it did get a bit more specific this time, and the lead international negotiator confirmed that these four issues were discussed. One of them was the Arak heavy water reactor. They're trying to find a way to assuage international concerns about that. It can produce plutonium, which is a potential nuclear weapons fuel. But Iran says it has no intention of dismantling it, so there's a search for a technical fix or some way to find a compromise on that.
They were also looking at enrichment, what are Iran's practical needs as far as enriched uranium. The West says Iran needs very little of it. Tehran is pointing to future nuclear power plants that may or may not be built. This is kind of an emotional issue for Iran, although Tehran is willing to negotiate what kind of enrichment it does and how much.
CORNISH: This round of talks has also attracted attention because of the tensions over Russia's moves in Crimea that's embroiled five of the six countries, right, in this group, the 5+1 group, that make up the international negotiating team. How has that affected things?
KENYON: Well, even as the talks broke up today, a senior U.S. official was saying it was there on the margins but inside the negotiating room, the Russians, as well as everyone else, kept focus on the nuclear issues. But then after the talks broke up, the head of the Russian delegation, Sergei Ryabkov, told the Interfax news agency that Russia may have to include what he called asymmetrical measures in its responses to EU and U.S. sanctions on Russia over its moves in Crimea and Ukraine.
Some are interpreting that to mean Russia could alter its view on the Iran nuclear question. Now, nothing like that has happened yet, but some analysts are already speculating that heightened tensions with the West could prompt Moscow to reduce its compliance with multilateral sanctions on Iran. And that would be very worrying for Washington.
CORNISH: Peter, in the meantime, is there much difference between how the West and Iran are portraying the talks?
KENYON: Well, there is what you might call a push by the Iranian side to get a move on. Both President Hassan Rouhani and Foreign Minister Mohammad Javad Zarif have been in the regular media, the social media, calling for more engagement. And in Tehran, we're seeing more noise from hard-line critics of the nuclear diplomacy and responses from the government. The Iran media watchdog, for instance, recently closed a conservative news weekly that had been criticizing the preliminary nuclear accord that is the basis for these talks. So I'd say there is a feeling of pressure building.
CORNISH: And these talks pick up again in just over two weeks with expert level talks in between. But is this a sign that things are going well or that the sides recognize what a long way there is to go in a limited time?
KENYON: I think more so the latter. There is a lot to do yet, and this is one of those negotiations where nothing is agreed to unless it's all agreed to. And that means that the very toughest issues will loom even larger as the clock keeps ticking. So there is still a commitment on both sides here to finish by the third week of July. But if that's impossible, they may have to extend this interim agreement for another six months. And that'll raise more criticism from the conservative benches and increase the risk of further sanctions on Iran.
CORNISH: That's NPR's Peter Kenyon at the Iran nuclear talks in Vienna. Peter, thank you.
KENYON: You're welcome, Audie. Transcript provided by NPR, Copyright NPR.