Collaboration between the state and the defense industry has long been seen as critical for national security. Nonetheless, scholarly studies on state defense industry relations (SDIR) are still limited in the field of public policy and administration. This article provides an empirical analysis and national case study of SDIR. Through process tracing methods and analysis of official documents and interviews transcripts, the case study investigates how the issue of ammunition security of supply (SoS) became prominent on the Swedish government’s agenda. The case is examined with a Multiple Streams Analysis (MSA) offering insights into policymaking and agenda-setting. The study makes at least three contributions: It addresses the need for bridging public policy and defense and security studies; it adds more empirical research on SDIR to defense and policy studies; and it offers lessons on how states can navigate security concerns in volatile times.