In the United States Army, the term combat service support was until 2008 defined as the essential capabilities, functions, activities, and tasks necessary to sustain all elements of operating forces in theater at all levels of war. Within the national and theater logistics systems, it includes but is not limited to that support rendered by service forces in ensuring the aspects of materiel and supply chain management, maintenance, transportation, health services, and other services required by aviation and ground combat troops to permit those units to accomplish their missions in combat. Combat service support encompasses those activities at all levels of war that produce sustainment to all operating forces on the battlefield. Within the United States Army, the traditional combat service support branches are the following:
