From the Document: "The underlying reason DOD has a military health system is medical readiness. The medical readiness mission involves promoting 'a healthy and fit fighting force that is medically prepared to provide the Military Departments with the maximum ability to accomplish their deployment missions throughout the spectrum of military operations.' The military health system also serves to 'create and maintain high morale in the uniformed services by providing an improved and uniform program of medical and dental care for members and certain former member of those services, and for their dependents' (10 U.S.C.1071). In addition, the resources of the military health system may be used to provide humanitarian assistance (10 U.S.C. 2561) and to perform medical research (10 U.S.C. 2358)."
CRS In Focus, IF10530
Federation of American Scientists: http://www.fas.org/sgp/crs/index.html