Political relations between Iran and the United States began in the mid to late 1800s, but had little importance or controversy until the post-World War II era of the Cold War and of petroleum exports from the Persian Gulf. Since then an era of close alliance between Shah Mohammad Reza Pahlavi's regime and the American government was followed by a dramatic reversal and hostility between the two countries after the 1979 Iranian Revolution.

Opinions differ over what has caused the decades of poor relations. Explanations offered include everything from the "natural and unavoidable" conflict between the Islamic Revolution on the one hand, and American "arrogance"  and desire for "global dictatorship" and "hegemony" on the other;to the regime's need for an "external bogeyman" to "furnish a pretext for domestic repression" against pro-democratic forces, and bind the regime to its "small but loyal and heavily armed constituency".