From the beginning of Iran's nuclear challenge in the International Atomic Energy Agency (History) and in spite of Iran's frequent clarifications and confidence-buildings, ambiguity and actions of the U.S and its allies against Iran have increased. (Background) As a result, the present article, in order to clarify and remove this ambiguity, faces this question that: What are the roots of America's dispute over Iran's peaceful nuclear activities especially the consensus of Western governments against Iran? (Question) The authors in their attempt to answer this question have investigated America's concern about the nature of the Islamic Revolution (main assumption) and its concern over Iran's inclination towards producing atomic weapons (rival assumption). (Hypothesis) Proving each of these hypotheses determines how the foreign policy of Iran should act against the U.S and its Western allies. (Objective) By investigating the main and rival hypotheses from the perspective of the Stephan Walt's balance of threat theory and based on its main premises, i.e. understanding threat and balance of threat, the objective of this research can be achieved. (Methodology) The result is that the issue of West's concern over Iran's access to atomic weapons does not match the reality; rather it results from the nature of the Islamic Revolution. (Findings