This legislation establishes a policy to strengthen strategic defense cooperation between the United States and its NATO allies located on the Eastern Flank. It recognizes the critical role these nations play in regional and transatlantic security, particularly in deterring aggression from hostile state actors. The bill specifically defines "Eastern Flank strategic defense partners" as NATO members bordering or in proximity to Russia, Belarus, or Ukraine, who commit to significant defense spending and host NATO forces. The Act mandates that the Secretaries of State and Defense prioritize these Eastern Flank partners for various forms of security assistance, including Foreign Military Financing , capacity building for foreign security forces, and the transfer of excess defense articles . These partners are also to be prioritized for participation in military exercises, interoperability training, and logistics planning to enhance their defensive capabilities and regional deterrence. To further bolster regional deterrence, the bill directs the Secretary of Defense to prioritize these partners under the War Reserve Stocks for Allies program and consider expanding stockpiles. A congressional briefing is required within 180 days to detail the implementation of these strategic defense cooperation and prioritization efforts.