Eastern Flank Strategic Partnership Act of 2025

Directs the State and Defense Departments to prioritize security cooperation with NATO Eastern Flank partners by giving them preference for U.S. security assistance programs, exercises, planning, and transfers of defense articles, and to manage and expand prepositioned stockpiles in the region to strengthen deterrence and speed response. Requires the Defense Department, working with State, to brief the appropriate congressional committees on implementation plans, timelines, goals, and cooperative mechanisms within 180 days after enactment.