Book excerpt: The doctrine discussed in this manual is nested with ADP 3-0, Operations, and describes the sustainment warfighting function. The endurance of Army forces is primarily a function of their sustainment and is essential to retaining and exploiting the initiative. Sustainment provides the support necessary to maintain operations until mission accomplishment. The relationship between sustainment and operation is depicted in introductory figure-1 on page vi.Sustainment must be integrated and synchronized with operations at every level to include those of our joint and multinational partners. Sustainment depends on joint and strategic links for strategic airlift, sealift, intratheater airlift, and strategic and theater-level supply support. Sustainment depends on our host nation (HN) partners to provide infrastructure and logistics support necessary to ensure both maneuver forces and followon sustainment are delivered to right place, at the right time, and in an operable condition.