This chapter examines the external collaboration between the police and the Norwegian Armed Forces, highlighting the importance of interagency cooperation in today’s complex security landscape. It outlines the structural, cultural, and legal frameworks that influence joint efforts in crisis prevention, preparedness, and management. The chapter emphasizes the significance of trust, shared situational awareness, and clearly defined roles, responsibilities, and authority. It explores the concept of total defense, where civil and military sectors are interdependent, and stresses the importance of joint exercises, liaison structures, and synchronized planning. Differences in command and control structures between the police and military are addressed, along with recommendations for improving crisis readiness through better organization, leadership, and mutual understanding. The use of Big Five team processes is identified as essential in strengthening collaboration, communication, and adaptability within and between organizations. While the collaboration between the police and Armed Forces is strong, the chapter concludes that there is potential for further enhancement through shared training, planning, and structural alignment.