Leaders of Iran and the U.S. have not had face-to-face contact in more than three decades.
U.S. President Jimmy Carter and Iran's Shah Mohammed Reza Pahlavi were the last to meet in 1977.
Diplomatic relations have been broken since 1980, over the 1979 takeover of the U.S. Embassy in Tehran by Iranian students.
U.S. Secretary of State Condoleezza Rice and Iranian Foreign Minister Manouchehr Mottaki fail to hold talks on the sidelines of a 2007 Sharm el-Sheikh conference on stabilizing Iraq, but they did say 'hello' to each other at a lunch.
U.S. President Barack Obama and Iranian President Hassan Rouhani have exchanged letters since Mr. Rouhani's 2013 election.
U.S. Secretary of State John Kerry and Iranian Foreign Minister Javad Zarif met on the sidelines of a Sept. 26, 2013 meeting in New York for the highest level direct talks between the countries in more than 30 years.