FILE - In this Nov. 15, 1977 file photo, then-first lady Rosalyn Carter, left, Shah Mohammad Reza Pahlavi, center, and then U.S. President Jimmy Carter, right, react to wafting tear gas as pro- and counter-shah demonstrators clash with police outside of the White House during a ceremony. Dozens would be injured in the violence. Forty years ago, Iran's ruling shah left his nation for the last time and an Islamic Revolution overthrew the vestiges of his caretaker government. The effects of the 1979 revolution, including the takeover of the U.S. Embassy in Tehran and ensuing hostage crisis, reverberate through decades of tense relations between Iran and America. (AP Photo, File)