Iran agreed not to produce nuclear weapons when it signed the Nuclear Nonproliferation Treaty in 1970, which opened the door for it to acquire civilian reactors. The treaty does not prohibit Iran from producing or possessing enriched uranium but requires it to submit its nuclear facilities to international monitoring to ensure that materials are not diverted to weapons use.
Iran has permitted inspections of its declared commercial nuclear facilities. But last year, an Iranian exile group pinpointed a secret underground enrichment plant outside Natanz, a small mountain town about 200 miles south of Tehran known for its bracing climate and fruit orchards.
In December, the Institute for Science and International Security, a small think tank in Washington, published satellite photos of Natanz from the archives of a commercial firm, DigitalGlobe. The photos showed large-scale construction inside the perimeter of a security fence. Among the buildings were a pilot centrifuge plant and two underground halls big enough for tens of thousands of centrifuges, the institute said.
Pressure mounted to allow international monitors into Natanz, and senior IAEA officials visited the plant in February. They found 160 assembled centrifuges and components for 1,000 more. Moreover, the equipment was to be housed in bunkers 75 feet deep, with walls 8 feet thick.
The level of centrifuge development at Natanz already reflects thousands of hours of testing and advanced technological work, experts said. By comparison, Iraq had tested a single centrifuge for about 100 hours when IAEA inspectors began dismantling Baghdad's nuclear weapons program after the 1991 Persian Gulf War.
"They are way ahead of where Iraq was in 1991," said a U.N. official who is familiar with both programs.
Once it is up and running, Natanz could make enough material for a bomb within a year and eventually enough for three to five bombs a year, experts said.
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Nuclear Neighbors
The Iranian exile group also revealed a secret site near Arak, a city of 400,000 in western Iran known as a historic center for weaving fine Persian carpets. Under international pressure, Iran conceded in February that it plans to build a special type of reactor there that will generate plutonium for research. Plutonium is the radioactive material at the heart of some of the most powerful nuclear bombs.
The disclosures cast previous Iranian government statements in a new light.
