This chapter outlines the technology behind the nuclear program to highlight the political and nonproliferation challenges that arise from it. Iran's nuclear program has been the target of a multilateral effort to constrain Tehran's nuclear ambitions and to uphold the rules of the nonproliferation treaty (NPT). The chapter describes whether and how the European Union (EU) pursued an effective multilateralism vis-a-vis Iran. French strategic thinker and nuclear expert, Therese Delpech distinguishes three potential rationales behind Iran's nuclear program: producing indigenous civilian nuclear fuel, using the nuclear program as a bargaining chip or acquiring the bomb. Summing up the findings on Iran's nuclear program, it is easy to see why this problem asks for a multilateral solution: with its clandestine activities, Iran has violated its International Atomic Energy Agency (IAEA) safeguards obligations under the NPT.