Long-term industry trends have strained the capacity of the U.S. defense industrial base to meet the growing demand for arms from partners, alongside the needs of the U.S. military. Adapting to a world of constrained supply and increasing market competition, while simultaneously expanding production capacity and developing innovative military technologies, requires examination of the defense industrial base in the context of arms production for export. Key knowledge gaps include the scale and structure of the defense industry, particularly non-prime contractors, the levers available to stimulate domestic and foreign investment in production capacity and to encourage new firms to enter the market, and the tradeoffs to international armaments cooperation, including co-development, coproduction, third-party licensing, co-sustainment, and third-party transfer. Additionally, research should assess the implications of constrained U.S. supply alongside a growing number of exporters for the prioritization of systems and foreign partners, commercial advocacy and communications, U.S. embassy operations, and arms transfer processes.