A report issued by the International Atomic Energy Agency (IAEA) said Iran had told the UN nuclear watchdog that it had begun building the plant within a bunker beneath a mountain near Qom in 2007, but the IAEA had evidence the project had begun in 2002.
The Islamic Republic said it decided to report the existence of the plant due to its commitment to the Nuclear Non-Proliferation Treaty. Iran told the Vienna-based agency that the site, which is guarded by heavy anti-aircraft weaponry, wouldn't be operational for 18 months and that no centrifuges have been installed in it as of yet.
US President Barack Obama said at the time that evidence of Iran's building the underground plant "continues a disturbing pattern of Iranian evasion" that jeopardizes global nonproliferation.