1981: Reza Amrollahi, the head of the Atomic Energy Organization of Iran, announces that huge uranium deposits have been discovered in four locations in Iran.
1984: Iran opens a nuclear research center at Isfahan with the assistance of China. Reports say that Chinese and Pakistani experts are assisting Iran with obtaining and processing enriched uranium.
1985: The foreign ministers of Iran, Syria and Libya say that their countries should develop nuclear weapons to counter the Israeli nuclear threat.
1985-86: Secret contacts between the United States and Iran lead to a complex deal in which the U.S. supplies conventional weapons to Iran in exchange for Iranian support in Lebanon and the funneling of money to support anti-communist guerrillas in Nicaragua.
Mid-1980s to early 1990s: Iran and North Korea begin cooperating on nuclear issues.
1995: The Clinton administration imposes sanctions prohibiting American companies and their foreign subsidiaries from doing business with Iran, including any financing or development of its oil and gas sector.
President George W. Bush names Iran, along with Iraq and North Korea, the "an axis of evil" during his State of the Union address on Capitol Hill in January 2002.
1998: Shortly after taking office, Iran's new reformist president, Mohammad Khatami, calls for a "dialogue among civilizations," raising hopes of a thaw in U.S.-Iranian relations.
2002: President George W. Bush names Iran, along with Iraq and North Korea, as part of "an axis of evil."
2003: Iran begins talks with the International Atomic Energy Agency (IAEA) and British, French and German foreign ministers on nuclear facility inspections. The Khatami government agrees to suspend work on uranium enrichment and allow stepped-up inspections.
2004: Iran agrees — for the time being — to comply with IAEA demands to halt uranium enrichment.
2005: Khatami is succeeded by hard-line conservative Mahmoud Ahmadinejad. Soon after, Iran announces it is resuming work on uranium enrichment.
Members of the United Nations Security Council unanimously approve sanctions against Iran in 2006.
2006: The U.N. Security Council imposes sanctions on Iran, blocking the import or export of sensitive nuclear material and equipment and freezing the financial assets of persons or entities supporting its proliferation sensitive nuclear activities or the development of nuclear-weapon delivery systems. The sanctions are tightened in subsequent Security Council action in 2007 and 2008.
2007: The U.S. intelligence community releases a National Intelligence Estimate report that claims Iran had suspended its nuclear weapons program in 2003, though its intentions still remain unclear. The NIE says Iran could probably not produce a bomb until the middle of the next decade.
2008: Speculation that Israel could strike at Iran's nuclear program mounts after a large-scale Israeli air force exercise and reports that Israel had made a secret request to the U.S., deflected by the Bush administration, for specialized bunker-busting bombs.
In May 2009, Iran test-fires a Sejil-2 missile, which could reach Israel and American bases in the Persian Gulf.
2009: In February, international inspectors say that Iran recently understated by one-third how much uranium it has enriched.
In April, the Obama administration says the U.S. would start participating with other major powers in negotiations with Iran over its nuclear program.
In May, Iran test-fires a Sejil-2 missile, which could reach Israel or American bases in the Persian Gulf.
In August, Iran agrees to grant United Nations inspectors greater access to its uranium-enrichment facility at Natanz and the nearly completed heavy water reactor outside Arak. The move comes in anticipation of a report from the International Atomic Energy Agency that is expected to be highly critical of Iran's nuclear program.
Sources: James Martin Center for Nonproliferation Studies at the Monterey Institute of International Studies/NTI, Council on Foreign Relations, Stratfor.com, Globalsecurity.org
