Since the Islamic Revolution in 1979, Iran's relationship with the United States has been antagonistic at best. 1979 was the year Islamist revolutionaries overthrew the sometimes brutal US-backed dictator, Mohammad Reza Pahlavi. Islamists took 53 Americans prisoner for over a year, demanding the return of the former dictator who had fled to America on "medical grounds." In the US, the hostage crisis helped sink Jimmy Carter's presidency and burned Iranian chants of "Death to America" into the public's collective consciousness.