US had been looking for a covert facility
Seen in satellite photos, the newly revealed Iranian facility near Qom looks as if it could be a Wal-Mart, a school, or a factory. But it's intended to house about 3,000 gas centrifuges, according to both Iranian and US officials. In terms of uranium-enrichment capability, that would make it a modest plant.
But to many US proliferation experts, Qom represents the danger of a second fuel cycle foretold. That's because Iran already has a large centrifuge farm, near Natanz. There, it has 8,300 installed centrifuges, though only about half are actually enriching uranium. It is big enough to house 54,000, according to the US.
Natanz itself was revealed to the world by an Iranian dissident group in 2002. Iran says the facility is intended to produce low-enriched uranium (LEU) for use in nuclear power reactors. Today it is under scrutiny by Western intelligence services and International Atomic Energy Agency inspectors, and many experts say it would be difficult for Iran to divert enough LEU from the Natanz production line to produce bomb-grade uranium elsewhere.
That has led many experts outside Iran to this conclusion: If the Iranians want to produce fissile material for weapons, they would be likely to do so at a hidden site. Natanz represents their first fuel cycle. This hidden site, or sites, would constitute the second.
The US intelligence community has predicted this. Two years ago, in their 2007 National Intelligence Estimate of Iran's nuclear intentions and capabilities, US analysts said: "We assess with moderate confidence that Iran probably would use covert facilities – rather than its declared nuclear sites – for the production of highly enriched uranium for a weapon."