This thesis is an analysis of the motivations behind U.S. efforts to stop Iran from developing a nuclear weapons program. It argues that U.S. actions must be viewed within a larger context; specifically it must be viewed from the perspective of the overall interests of the U.S. in the Middle East. These interests include ensuring access to Middle Eastern oil, protecting the state of Israel and eliminating security threats, to the U.S. and its allies, especially from terrorist organizations. The thesis examines U.S.-Iran’s relationship over the nuclear issues a historical context, beginning with Eisenhower Administration. It is guided by the insights derived from the realist paradigm in International Relations theory which stresses national interest, defined in terms of power as the major determinant in state behaviour. The study shows that the U.S. was quite supportive of Iran developing nuclear energy for peaceful purposes only when relations between the two states were cordial. However, since the Islamic Revolution of the late 1970s, the relationship has been marked by hostility on both sides, and importantly, by American attempts to contain Iran’s nuclear ambitions, particularly its goal of developing a nuclear weapons program, and the latter’s efforts to circumvent these. An Iran in possession of nuclear weapons is seen as a dangerous threat to Middle Eastern stability and, of course, to U.S. interests in the region.