In 2002, the International Atomic Energy Agency (IAEA) began investigating allegations that Iran had conducted clandestine nuclear activities. Ultimately, the agency reported that some of these activities had violated Tehran's IAEA safeguards agreement. The IAEA has not stated definitively that Iran has pursued nuclear weapons, but has also not yet been able to conclude that the country's nuclear program is exclusively for peaceful purposes. The IAEA Board of Governors referred the matter to the U.N. Security Council in February 2006. Since then, the council has adopted six resolutions, the most recent of which (Resolution 1929) was adopted in June 2010. The Security Council has required Iran to cooperate fully with the IAEA's investigation of its nuclear activities, suspend its uranium enrichment program, suspend its construction of a heavywater reactor and related projects, and ratify the Additional Protocol to its IAEA safeguards agreement. However, a November 2011 report from IAEA Director-General Yukiya Amano to the agency's Board of Governors indicated that Tehran has continued to defy the council's demands by continuing work on its uranium enrichment program and heavy-water reactor program. Iran has signed, but not ratified, its Additional Protocol. Iran and the IAEA agreed in August 2007 on a work plan to clarify the outstanding questions regarding Tehran's nuclear program. Most of these questions have essentially been resolved, but then-IAEA Director-General Mohamed ElBaradei told the agency's board in June 2008 that the agency still has questions regarding "possible military dimensions to Iran's nuclear programme." The IAEA has reported for some time that it has not been able to make progress on these matters. This report provides a brief overview of Iran's nuclear program and describes the legal basis for the actions taken by the IAEA board and the Security Council.