This research paper illustrates as well as analyzes the complex interagency relationship between the State Department and Defense Department to protect US diplomatic facilities abroad. First, it describes the responsibilities and organization of the State Department abroad and then explains how various Defense Department elements support the State Department’s Bureau of Diplomatic Security to provide a safe platform for the conduct of foreign diplomacy. Using a case study approach, it then takes a critical look at the marine security guard, naval support unit, and special operations partnerships with the State Department to assess their effectiveness and concludes with recommendations for improvement. The thesis is that increases in professional education exchange and liaison officer programs along with changes in institutional culture to place higher value on interagency assignments can provide tomorrow’s civilian and military leaders an opportunity to identify common values, create interagency friendships, and build more cooperative working relationships to enhance the security posture of US diplomatic facilities overseas.