Tehran, Iran— Iran has begun uranium enrichment at a new underground site built to withstand possible airstrikes, a leading hard-line newspaper reported Sunday in another show of defiance against Western pressure to rein in Tehran's nuclear program.
The operations at the bunker-like facility south of Tehran, reported by the Kayhan daily newspaper, are small in comparison to Iran's main enrichment site. But the centrifuges at the underground labs are considered more efficient and are shielded from aerial surveillance and protected by up to 300 feet of mountain rock.
Uranium enrichment is at the core of the international standoff over Iran's nuclear program. The U.S. and its allies fear Iran could use its enrichment facilities to develop high-grade nuclear material for warheads.
Iran — which claims it only seeks nuclear reactors for energy and research — has increased threats and military posturing against pressures, including U.S. sanctions targeting Iran's Central Bank in attempts to complicate its ability to sell oil. A senior commander of the Revolutionary Guard force was quoted as saying Tehran's leadership has decided to order the closure of the Strait of Hormuz, a strategic oil route, if the country's petroleum exports are blocked.
In an interview broadcast Sunday, U.S. Defense Secretary Leon Panetta said Iran is laying the groundwork for making nuclear weapons someday, but is not yet building a bomb. Panetta reiterated U.S. concerns about a unilateral strike by Israel against Iran's nuclear facilities.
