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A senior delegation from the International Atomic Energy Agency arrives in Tehran on Sunday. They'll make one more effort to probe Iran's nuclear program for signs of nuclear weapons work. The IAEA disclosed its concerns in a controversial report last November. Until now, Iran has refused to discuss evidence that it is engaging in nuclear weapons development.
But as NPR's Mike Shuster reports, international pressure on Tehran is growing and may help to shake loose some answers.
MIKE SHUSTER, BYLINE: For years, the IAEA has been trying to get answers to some very uncomfortable questions about Iran's nuclear program. The Iranians have dismissed the matter, claiming the intelligence the agency has comes from the United States and Israel, and is forged.
But in last November's report, the IAEA said it now possesses consistent intelligence on Iran's activities from numerous states. Not so easy to dismiss, says Leonard Spector, a specialist on nuclear issues at the Martin Center for Non-Proliferation Studies in Monterey.
DR. LEONARD SPECTOR: The Iranians have been put on the spot by the actual content of the last IAEA report, you know, accusing them of being involved in militarily-related activities.
SHUSTER: Spector notes there are several areas where Iran has pursued nuclear activities that could only be related to weapons.
SPECTOR: There are questions about experiments with explosives, which would be relevant to detonating a nuclear device. There are documents that they have regarding certain components that are shaped in a way that would only be suitable for a nuclear device.
SHUSTER: The agency also possesses intelligence on Iran's work with neutron initiators that are used to spark a nuclear detonation. And it has received the information from as many as 10 nations, notes Muhammad Sahimi, an Iran analyst who writes for the website Tehran Bureau.
DR. MUHAMMAD SAHIMI: That also made it tougher for Iran to claim that these are all based on forged documents and discredited reports. So in that sense, Iran has been in a tighter position than before.
SHUSTER: Still, Sahimi says, Iran is likely to fall back on its old explanations.
SAHIMI: I don't expect any breakthrough during this upcoming visit to Tehran, simply because neither side has really changed its position. The IAEA insists that Iran should explain some of these issues, and Iran has insisted that a lot of these issues are actually fake.
SHUSTER: This upcoming set of talks in Tehran is rare. The IAEA sends its monitors into Iran every month to check on known nuclear activities, such as uranium enrichment. The last talks to probe the more puzzling questions were held three years ago.
The United States cautiously welcomed the effort to discuss these unresolved issues, in the words of State Department spokesperson Victoria Nuland.
VICTORIA NULAND: There were a huge number of questions raised by the November report. They will be seeking to answer those questions. And, you now, it's incumbent on Iran to be supportive.
SHUSTER: The upcoming talks were set some weeks ago. And then, in mid-January, Iran also agreed to hold negotiations with the U.S., the European Union, and Russia and China over its known nuclear activities.
But earlier this week, the Europeans decided to impose what amounts to an oil embargo on Iran, the toughest sanctions against Iran so far, an action that pleased Britain's foreign secretary, William Hague.
WILLIAM HAGUE: This shows the resolve of the European Union and is absolutely right to do this, in view of Iran's continued breach of U.N. Security Council resolutions and refusal to come to meaningful negotiations on the nuclear program.
SHUSTER: It's not clear yet whether these sanctions, which don't take full effect until July, will persuade Iran to negotiate more seriously or will make it more intransigent.
Leonard Spector is hopeful the pressure will do what it's meant to do.
SPECTOR: The totality of the pressures that are being brought to bear are quite substantial. It's a big change from a year or two ago. And it would be surprising not to see a little bit of movement, at least, from the Iranians. And perhaps, you know, we'll find to our surprise that we're really about to make some progress.
SHUSTER: The IAEA's visit to Tehran begins on Sunday and is expected to last for three days.
Mike Shuster, NPR News.
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