<p>The decoupling of Europe from Russian energy markets following the 2022 Russia-Ukraine war represents one of the most significant shifts in the global energy system in recent decades. This study examines how Europe’s move away from Russian fossil fuels and its growing reliance on alternative suppliers, particularly the United States, is reshaping energy security and geopolitical relations. The central research question asks to what extent Europe’s energy decoupling from Russia and its realignment with the United States has strengthened or weakened European energy security, and how this transformation is affecting broader geopolitical dynamics. The paper advances the hypothesis that although Europe has significantly reduced its immediate vulnerability to Russian energy leverage through diversification strategies and increased imports of Liquified Natural Gas (LNG), the emerging reliance on new suppliers may create different forms of strategic dependence and economic vulnerability. To analyse these developments, the study employs a theoretical framework that draws on realism, liberal institutionalism and constructivism in order to capture the strategic, institutional and normative dimensions of energy politics. Methodologically, the research adopts a qualitative approach based on secondary data sources, including institutional reports, policy documents and scholarly literature. The analysis is supported by comparative case studies of Germany, Poland and the Baltic States that illustrate different national responses to the energy crisis and diversification strategies within the European Union. The findings suggest that while Europe has made considerable progress in reducing dependence on Russian energy supplies, long-term energy security will depend on sustained diversification, accelerated renewable energy development, and the management of emerging geopolitical dependencies in global energy markets.</p>