Some scholars suggest that the European Union (EU) is a global actor, and its foreign policy is based on the norms and principles that have shaped and consolidated the EU itself. Reviewing the current literature on the Normative Power Europe notion and using Natalie Tocci's framework to assess normativity in foreign policy, this paper investigates to what extent the EU has been capable of independently formulating and effectively implementing its normative foreign policy on the case of the Iranian nuclear program since 2003, where the EU has sought to make Iran abide by the international law norm of non-proliferation of nuclear weapons. The research identifies that the formation and implementation of EU normative policies have been mainly challenged by the Realpolitik of the US, driving the EU to adopt non-normative policies or leading to embarrassing instances of inaction in the EU foreign policy for which normative power approaches offer less explanatory power. Concomitantly, the research illustrates how over time, the EU has shown greater determination to act autonomously on the Iranian nuclear profile.