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FILE -A file satellite image taken Sunday Sept. 27, 2009, provided by DigitalGlobe, shows a suspected nuclear enrichment facility under construction inside a mountain located north of Qom, Iran. The Washington-based Institute for Science and International Security, which has closely followed Iranian nuclear developments, says it believes this satellite photo of a site on a military base near Qom, Iran, is most likely the location of the newly revealed centrifuge facility. (AP Photo/DigitalGlobe, File)

Iran's deadly nuclear sites

Iran has significantly stepped up its output of low-enriched uranium and total production in the last five years would be enough for at least five nuclear weapons if refined much further, a U.S. security institute said.