August 2002:                National Council of Resistance of Iran (NCRI), an exiled Iranian opposition group, reveals two secret nuclear sites under construction in Iran, one at Natanz and one at Arak.

September 2002:          The head of Iran's Atomic Energy Organization announces Iran's "long-term plan to construct nuclear power plants...within two decades," and the International Atomic Energy Agency (IAEA) asks about the sites at Natanz and Arak.

December 2002:           Satellite photographs of Natanz and Arak are publicized in the media, suggesting that Natanz is probably a centrifuge uranium enrichment site and Arak is a heavy water production plant.

White House spokesman Ari Fleischer says that revelations regarding Natanz and Arak reinforce U.S. fears about Irans "across-the-board pursuit of weapons of mass destruction and missile capabilities."

January 2003:               Two senior U.S. officials - Zalmay Khalilzad from the White House and Ryan C. Crocker from the State Department - reportedly meet secretly with Iranian officials to discuss potential cooperation.

February 2003:             IAEA visits Natanz, which includes a pilot fuel enrichment plant intended to house 1,000 centrifuges and a large-scale commercial enrichment facility intended to house 50,000 centrifuges.  Iran confirms that a heavy water production plant is under construction at Arak.  Iran also acknowledges secretly importing uranium compounds in 1991.

May 2003:                   According to a report in the Financial Times, Iran uses the "Swiss channel" to make a proposal reportedly covering progress on its nuclear program, its support for terrorism, its influence in Iraq, and its role in the Israeli-Palestinian conflict in exchange for lifting sanctions, dropping "regime change" from the U.S. policy lexicon, and the eventual re-establishment of diplomatic relations.  U.S. issues no response.

Iran informs the IAEA of plans to construct a 40 MW (t) heavy water reactor at Arak and a fuel manufacturing plant at Isfahan.

                                    U.S. reportedly boycotts a scheduled meeting with Iran because Iran is suspected of harboring organizers of a recent terrorist bombing in Riyadh, Saudi Arabia.  The meeting would have been the latest in a series of informal bilateral talks on cooperation on terrorism, Iraq and Afghanistan.

NCRI claims that the Iranian government has developed two additional uranium enrichment facilities, at Lashkar-Abad and Ramandeh village, which it intends to use as enrichment sub-stations or back-up stations in the event of a military attack on its main facility at Natanz.

June 2003:                    IAEA board discusses Director-General Mohamed ElBaradei's report that "Iran has failed to meet its obligations" concerning "the reporting of nuclear material, the subsequent processing and use of that material and the declaration of facilities where the material was stored and processed."

Iran introduces uranium hexafluoride (UF6) into the first centrifuge at Natanz.

President George W. Bush announces that "the international community must come together to make it very clear to Iran that we will not tolerate the construction of a nuclear weapon in Iran."

July 2003:                     The medium-range Shahab-3 missile is distributed to Iran's Revolutionary Guard several weeks after what an Iranian foreign ministry spokesman calls the "final test" of the Shahab-3.

August 2003:                Israeli Prime Minister Ariel Sharon and an Israeli general brief President Bush on Iran's nuclear program, arguing that U.S. intelligence services are underestimating how quickly Iran could develop a nuclear weapon.

IAEA takes environmental samples at the Kalaye Electric Company, a centrifuge workshop, and visits the two nuclear sites at Lashkar-Abad and Ramandeh village.

Iran begins testing a small ten-machine cascade at Natanz and admits to the IAEA that it conducted "bench scale" uranium conversion experiments in 1990s.

September 2003:          IAEA board discusses ElBaradei's latest report on Iran.  The report describes contradictions and misstatements made by Iran and says that two types of enriched uranium particles were found at Natanz, that the centrifuges at Natanz resemble an early European design, and that the centrifuges were tested using UF6.

U.S. tries to push through a resolution at the IAEA that would find Iran in non-compliance with its international obligations and send it to the U.N. Security Council, but backs down due to lack of support and agrees to give Iran "a last chance to stop its evasions."

IAEA board calls on Iran to provide full transparency on its nuclear program, to suspend its uranium enrichment related activities, and to resolve all outstanding questions by the end of October.

Russian President Vladimir Putin and President Bush discuss Iran's nuclear program during meetings at Camp David.  Bush describes the meeting as "very satisfactory," and Putin endorses the IAEA's ongoing investigation.

October 2003:              Iran agrees with foreign ministers from Germany, France and Britain that Iran will sign IAEA's Additional Protocol and suspend uranium enrichment and reprocessing activities in exchange for access to technology.   

Single machine tests using UF6 are carried out at Natanz, and the installation of a 164-machine cascade is finalized.

IAEA inspectors visit Natanz on October 31 and confirm that no UF6 is being fed into centrifuges (as required under the terms of Iran's deal with Germany, France and Britain).  However, construction and installation work continues.

November 2003:          A C.I.A. report accuses Iran of "vigorously" pursuing nuclear, chemical and biological weapon programs and seeking help from Russia, China, North Korea and Europe.  The report also says that the U.S. remains convinced that Tehran is pursuing a clandestine nuclear weapon program.

Iran shuts down all centrifuges at Natanz but continues to assemble centrifuges.

                                    IAEA board discusses ElBaradei's report that high and low enriched uranium particles were found at Kalaye, that Iran secretly produced uranium enriched to 1.2% U-235 at Kalaye between 1999 and 2002, that Iran ran a secret laser enrichment program, and that Iran conducted secret plutonium production experiments.  However, the report concludes that there is still no evidence that Iran has a bomb program despite its policy of concealment.

U.S. again pushes for the IAEA to declare Iran in violation of the Nuclear Non-Proliferation Treaty and to report Iran to the U.N. Security Council.

IAEA calls on Iran to correct its failures, but does not refer Iran's nuclear dossier to the U.N. Security Council.

December 2003:           Iran signs the Additional Protocol to its IAEA Safeguards agreement and agrees to act within the Protocol's provisions pending its official entry into force through ratification by Iran's parliament.

February 2004:             Iran expands its suspension of uranium enrichment activities to include manufacturing, testing and assembling centrifuges.  However, some centrifuge manufacturing will continue under existing contracts.

March 2004:                IAEA board discusses ElBaradei's report on traces of uranium enriched to 36% U-235 found at Kalaye, Iran's work on the radioactive isotope Polonium 210, which can be used to set off a nuclear explosion, and Iran's previously unknown work on a second generation Pakistani centrifuge called the P-2.

IAEA passes a third resolution, which criticizes Iran's lack of transparency and honesty.