A recent CIA Report to Congress discussing Iran's nuclear program says that Iran continued to expand its nuclear infrastructure and uranium enrichment activities in 2011. Iran's progress included enriching uranium at the underground Natanz location with first-generation centrifuges, while also testing and operating advanced centrifuges at the Natanz pilot plant. According to the CIA, as of November 2011, Iran had produced 4,900 kilograms of low-enriched uranium, compared to 3,200 kilograms by November 2010 and 1,800 kilograms in November 2009. Iran's holdings included approximately 80 kilograms of 20-percent enriched uranium, the report stated.Iran has also started to produce 20% enriched uranium at the Fordow Fuel Enrichment Plant near Qom.An IAEA report published on February 24 showed Iran had now produced nearly 110 kilograms of uranium enriched to 20% since early 2010. Western experts say about 250 kilograms is needed for a nuclear weapon.The CIA report states that the number of operating centrifuges is estimated at 6,200, up from 3,800 in August 2010.The report notes that some obstacles slowed Iran's progress over the course of the year, but does not specify further.Iran has also moved forward with its ballistic missile program, which it considers its primary deterrent, according to the CIA.In late June and July 2011, Iran launched a series of missiles and rockets as part of its Noble Prophet VI military exercise, including Shahab-1/2 SRBMs, a Shahab-3 MRBM and Zelzal rockets. Iran publicized its underground ballistic missile silos which it says are less vulnerable to attack, the report stated.