International Atomic Energy Agency and the Legitimacy of Nuclear Power: The Case of Lithuanian-Belarusian Dispute Over Ostrovets NPP

International organizations play an important role in judging the legitimacy of its member states’ policies. In accordance with their institutional mandate, moral authority and international norms, international organizations legitimize or delegitimize national policies by framing a positive or negative public discourse about them. Because legitimacy is associated with policy effectiveness and international organizations are generally understood as one of its sources, states often devote substantial resources to legitimize their policies through international organizations. One of such instances is Lithuanian and Belarusian dispute regarding Ostrovets NPP. Lithuania and Belarus perceive International Atomic Energy Agency (IAEA) as an organization with the most significant authority in nuclear safety, capable of assessing the compliance of Ostrovets Nuclear Power Plant (NPP) with the international nuclear safety standards. On the one hand, IAEA emerges as one of the most important international institutions through which Lithuania sought to reveal the shortcomings of the Ostrovets NPP while attempting to legitimize its opposition to the construction of this nuclear power plant. On the other hand, however, IAEA stands out as crucial tool for Belarus to legitimize its decision to build Ostrovets NPP and to question Lithuanian opposition. Given the relevance of IAEA in Lithuanian and Belarusian foreign policies, the paper examines IAEA's public discourse on nuclear energy in Belarus. It aims to assess its role in the process of (de)legitimizing Ostrovets NPP. After analyzing the IAEA’s leadership statements, the official press releases and the reports published by the peer-review missions during 2007 – 2020, the paper concludes that the IAEA constructed a public discourse that exclusively favored Belarus, thus legitimizing its NPP. One sided public support for Belarus, however, does not take into account other well-established facts (violations of international treaties, incidents, suppression of environmental activists, etc.) that question the objectivity of IAEA’s peer-review system.