This bill, titled the "The U.S.-European Nuclear Energy Cooperation Act of 2025," mandates the Secretary of State, in consultation with other federal agencies, to develop a comprehensive strategy. The primary goal of this strategy is to strengthen United States-European nuclear energy cooperation and actively combat Russian malign influence within the European nuclear energy sector. The legislation highlights Russia's invasion of Ukraine and its systematic targeting of energy infrastructure, as well as Russia's use of nuclear power designs and fuel services to exert influence and threaten energy security in Europe. It emphasizes the need for the U.S. and its allies to prioritize American, European, and partner products and services in developing nuclear industries, while maintaining strong nonproliferation, security, and safety standards. The required strategy must include an assessment of efforts to broaden U.S. nuclear industry participation in Europe and promote the competitiveness of U.S., European, and partner technologies against Russian and Chinese offerings. It will also detail different nuclear reactor types and fuel cycles, analyzing their potential to reduce Russia's market share in Europe for uranium, conversion, enrichment, and reactor fuel by specific future dates. Furthermore, the strategy will examine U.S. government-funded nuclear technologies, their potential to decrease Russia's market share, and their impact on minimizing weapons-usable nuclear material. It will also provide an overview of U.S. diplomatic engagements, European countries' nuclear policies, existing and potential areas of cooperation, and Russian and Chinese influence in the sector. The bill also requires an assessment of Rosatom's role in Russia's energy sector, including its strengths and vulnerabilities. An overview of how the U.S. balances strategic collaboration with allies against commercial competitiveness issues is also mandated. Finally, the bill authorizes an appropriation of $30,000,000 for each of fiscal years 2025 through 2029 to support engagement in Europe, focusing on capacity building, early-stage project support, and countering Russian disinformation campaigns.