UN experts are inspecting the heavy water production plant in Arak, Iran, on Sunday. The visit is the first test of an interim deal Iran struck with the West in November. Hamid Foroutan/AFP/Getty Images hide caption

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Inspectors from the International Atomic Energy Agency are scheduled to visit Iran's heavy-water reactor in the city of Arak on Sunday as part of an international deal on the country's nuclear program. Hamid Forutan/EPA/Landov hide caption

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Iranian Foreign Minister Mohammad Javad Zarif speaks during a news conference earlier this month. Ahmad Al-Rubaye/AFP/Getty Images hide caption

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April 2010: Iranian President Mahmoud Ahmadinejad unveils a sample of the third generation centrifuge for uranium enrichment during a ceremony in Tehran on April 9, 2010. Iran says its nuclear ambitions are peaceful. Behrouz Mehri/AFP/Getty Images hide caption

itoggle caption Behrouz Mehri/AFP/Getty Images