Iran plans to install more sophisticated equipment at its main nuclear enrichment plant, which will greatly accelerate its processing of uranium. Iranian officials reportedly sent a note to the International Atomic Energy Agency saying it plans to upgrade the centrifuges at its enrichment facility at Natanz, and the upgrade could make the enrichment process two to three times faster. Iranian officials informed the watchdog group of the plan January 24, and the IAEA replied January 29, asking for more technical information about the plan. The Natanz plant is used to enrich uranium to less than 4 percent. But a newer enrichment plant, near the city of Qum, is more troubling, because it is buried deep underground, making it better able to withstand an attack.