The U.S. Militarys Force Structure: A Primer

In fiscal year 2015, the Department of Defense DoD spent a total of roughly 390 billion on operation and support O and S of military units. The O and S budget covers the costs associated with the day-to-day running of units. Those costs include pay and benefits for military personnel, compensation for most civilian employees, health care costs for military and civilian personnel, and the daily expenses of operating a unit, such as equipment maintenance, training, support contractors, and so on. The O and S budget makes up about two-thirds of DoDs total base budget, which is the defense budget excluding additional funds provided specifically for wartime operations. The rest of DoDs base budget is spent on acquiring weapon systems and constructing buildings and other infrastructure.The size and complexity of the U.S. armed forces can make it difficult to determine how the O and S budget is distributed among units. In this report, the Congressional Budget Office analyzes the structure and cost of the military from the perspective of major combat units, such as Army brigades, Navy aircraft carrier strike groups, Marine Corps task forces, and Air Force squadrons. CBO allocates most of the O and S budget and DoDs total number of military personnel among major combat unitsand their associated support units and overhead activitiesto provide a clearer picture of the size and cost ofthe major elements of the militarys force structure. Such information can help policymakers evaluate proposals to change the structure or budget of the armed forces.