A history of official contact — and near misses — between U.S. and Iranian officials.

Relations cooled in early 1979 when Ayatollah Khomeini ousted the Shah. In November of that year Iranian militants seized the U.S. Embassy and took 52 Americans hostage for 444 days. This led the United States to cut off diplomatic relations with Iran.

— March 2007: U.S. and Iranian envoys participated in a conference in Baghdad.

— Sept. 2006: U.S. Secretary of State Condoleezza Rice was in the same room at the United Nations as the Iranian Foreign Minister Manouchehr Mottaki during a meeting on Iraq.

— May 2006: Iranian President Mahmoud Ahmadinejad wrote U.S. President George W. Bush a rambling 18-page letter, lambasting the U.S. leader for his handling of the Sept. 11 attacks.

— Nov. 2004: U.S. Secretary of State Colin Powell was seated at dinner next to his Iranian counterpart, Kamal Kharrazi, during a 20-nation meeting in Egypt to discuss Iraq's future.

— 2001-02: Officials from both sides communicated before and after the U.S. invasion of Afghanistan to topple the Taliban, whom Tehran also opposed.

— Sept. 2000: U.S. President Bill Clinton lingered after his address to the United Nations to hear Iranian President Mohammad Khatami speak. U.S. Secretary of State Madeleine Albright and Kharrazi both attended an eight-nation meeting on Afghanistan.

— March 2000: The Clinton administration lifted a ban on U.S. imports of Iranian luxury goods and said it would seek a legal settlement that could free Iranian assets frozen since 1979.

— 1985-86: A series of secret meetings took place between the U.S. and Iran, in which the United States sold weapons to Iran and gave the proceeds to Central American rebels. The scandal came to be known as the Iran-Contra affair.

— April 1980: The United States broke diplomatic relations with Iran and imposes economic sanctions over the hostage crisis.

— May 1975: Shah Mohammed Reza Pahlevi visited the United States and met with President Gerald Ford.