From the Summary: "International Atomic Energy Agency (IAEA) inspections since 2003 have revealed almost two decades' worth of undeclared nuclear activities in Iran, including uranium enrichment and plutonium separation efforts. Iran agreed in 2003 to suspend its enrichment and reprocessing activities in exchange for promises of assistance from Germany, France, and the UK (EU-3), but negotiations broke down in August 2005. On September 24, 2005, the IAEA Board of Governors found Iran to be in noncompliance with its Nuclear Nonproliferation Treaty (NPT) safeguards agreement (GOV/2005/77) and voted (GOV/2006/14) on February 4 to report Iran to the U.N. Security Council. The Security Council issued a presidential statement on March 29 that called upon Iran to reinstitute its voluntary suspension of enrichment and reprocessing and asked the IAEA to report on Iran's compliance by April 28. On April 11, Iranian officials announced that they had enriched some uranium to 3.5% enrichment (fuel-grade). This report will be updated as needed."
CRS Report for Congress, RS21592