The war in Ukraine is having transformative effects on international relations. The first months of President Trump’s second term have already further intensified its disruptive impact on the European Union’s geopolitical position. As a compelling case study, this paper analyzes Belgium’s evolving perception of its national interest since February 2022 in the context of great power rivalries and economic sanctions. The analysis draws on seven months of field research at the Belgian Ministry of Foreign Affairs. Experience working on the EU’s twelfth package of sanctions is complemented by a dozen semi-structured interviews with prominent diplomats. While multilateral alliances remain Belgium’s principal source of influence, perceptions of aligning interests are subtly shifting in certain areas. For a long time, Belgium’s national interest has been closely intertwined with the EU’s general interest. However, the war in Ukraine has reignited debates on territorial integrity, the defense of multilateralism, and the promotion of economic prosperity. The conflict has also highlighted Belgium’s unique position on key issues such as SWIFT, frozen Russian assets, and the diamond sector. Within the framework of a geopolitical Commission, Belgium’s voice—though traditionally discreet—has become more assertive in defending rediscovered national interests that no one else would advocate for.