The United States biological defense program — in recent years also called the National Biodefense Strategy — began as a small defensive effort that paralleled the country's offensive biological weapons development and production program, active between 1943 and 1969. Organizationally, the medical defense research effort was pursued first (1956-1969) by the U.S. Army Medical Unit (USAMU) and later, after the discontinuation of the offensive program, by the U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID). Both of these units were located at Fort Detrick, Maryland, where the U.S. Army Biological Warfare Laboratories were headquartered. The current mission is multi-agency, not exclusively military, and is purely to develop defensive measures against bio-agents, as opposed to the former bio-weapons development program.