Key figures in the secret U.S.-Iranian nuclear talks:
—President Barack Obama: Making good on a promise in his first inaugural to "extend a hand" to countries like Iran, Obama authorizes secret, one-on-one contacts between American and Iranian officials after the release of two American hikers from an Iranian prison in September 2011. He steps up the effort in March of this year, dispatching two top foreign policy aides to Oman for discussions with Iran on everything from the nuclear program to the Syrian civil war and the fate of three Americans believed to be in Iranian custody. Nuclear talks accelerate after Iran's moderate President Hassan Rouhani takes office in August. Obama and Rouhani speak by telephone in September, the first direct contact between U.S. and Iranian leaders in more than three decades.
—Deputy Secretary of State William Burns: A 31-year veteran of the foreign service, Burns is only the second career diplomat to climb to the No. 2 position at the State Department. A fixture in several of America's most sensitive diplomatic efforts in recent years, he serves as America's representative when President George W. Bush decides to join nuclear talks between world powers and Iran in 2008.
Obama then taps Burns as one of two men to meet with the Iranians in secret this year.
—Jake Sullivan, deputy assistant to the president and national security adviser to the vice president: Still in his 30s, Sullivan is a rising star of U.S. foreign policy. After serving as a Senate aide, the former Rhodes scholar joins Hillary Rodham Clinton's 2008 presidential campaign and then follows her to the State Department, rising to policy planning chief in 2011. When Clinton leaves government in February, Sullivan moves over to the White House to become Vice President Joe Biden's national security adviser. Shortly after, Obama entrusts him with co-leading the Oman mission.
—Undersecretary of State for Political Affairs Wendy Sherman: A veteran of nuclear talks with North Korea during Bill Clinton's presidency, Sherman rejoins the State Department in 2011 and serves as America's lead nuclear negotiator with Iran. She is initially kept away from the secret diplomacy while representing the U.S. at official "P5+1" gatherings between world powers and Iran. She joins Burns and Sullivan after Rouhani becomes Iran's president. In November, she seeks to incorporate the progress the U.S. and Iran reach privately into the larger negotiations.
—Ayatollah Ali Khamenei: The supreme leader of Iran, Khamenei has the ultimate say on Iran's nuclear program. Despite his regular outbursts against Israel and the United States, the Obama administration says he signs off on secret contacts between midlevel U.S. and Iranian officials in 2011. Khamenei then agrees to authorize higher-level officials to meet with American counterparts in private this year. Khamenei has issued a religious fatwa against nuclear weapons, but the U.S. and others say they need proof.
—President Hassan Rouhani: A former nuclear negotiator, Rouhani decisively wins Iran's presidential election in June and promises a new relationship with the West after eight years of hostility under Mahmoud Ahmadinejad. A self-proclaimed moderate, Rouhani promises nuclear concessions to satisfy international concerns while insisting that Iran maintain its right to enrich uranium for peaceful purposes. He starts sending some of his own aides to the secret talks with the United States after his August inauguration.
—Foreign Minister Mohammed Javad Zarif: Rouhani's American-educated foreign minister, Zarif enters office seeking to repair Iran's relations with the world. He reaches out to Jews with a Rosh Hashana message and distances himself from Ahmadinejad's legacy by recognizing the Holocaust. In the past two months, Zarif meets twice with Secretary of State John Kerry in the highest-level, face-to-face talks between the U.S. and Iran since the 1979 Islamic Revolution and subsequent U.S. Embassy hostage crisis.
Sultan Qaboos: The Middle East country's dynastic ruler, who ousted his father in a 1970 coup, Qaboos is unique for the close relations he has maintained with the United States and Iran. After a group of American hikers is arrested in Iran in 2009, he serves as a key mediator between the two countries. Oman facilitates the bail payments to Iran for the release of the female prisoner in 2010 and two men in 2011. The sultan then facilitates the subsequent meetings between U.S. and Iranian officials in the Omani capital of Muscat. After Rouhani assumes office, Qaboos is the first foreign leader to visit the new Iranian president