The United States Department of Defense organizes various agencies providing services such as medical assistance, for example, akin to other nations' militaries.
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.
Combat service support encompasses those activities at all levels of war that produce sustainment to all operating forces on the battlefield.
Sustainment is one of the six warfighting functions, which also include movement and maneuver, intelligence, fires, command and control, and protection.
The Marine Corps Logistics Command (MARCORLOGCOM) is the preferred provider of supply chain management, collaborative maintenance management and strategic prepositioning to the operating forces of the United States Marine Corps and other services and agencies.