The U. S. Military's Force Structure: a Primer

n fiscal year 2015, the Department of Defense (DoD)spent a total of roughly $390 billion on operation andsupport (O&S) of military units. The O&S budget coversthe costs associated with the day-to-day running ofunits. Those costs include pay and benefits for militarypersonnel, compensation for most civilian employees,health care costs for military and civilian personnel, andthe daily expenses of operating a unit, such as equipmentmaintenance, training, support contractors, and so on.The...
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n fiscal year 2015, the Department of Defense (DoD)spent a total of roughly $390 billion on operation andsupport (O&S) of military units. The O&S budget coversthe costs associated with the day-to-day running ofunits. Those costs include pay and benefits for militarypersonnel, compensation for most civilian employees,health care costs for military and civilian personnel, andthe daily expenses of operating a unit, such as equipmentmaintenance, training, support contractors, and so on.The O&S budget makes up about two-thirds of DoD'stotal "base" budget, which is the defense budget excludingadditional funds provided specifically for wartimeoperations. (The rest of DoD's base budget is spent onacquiring weapon systems and constructing buildingsand other infrastructure.)The size and complexity of the U.S. armed forces canmake it difficult to determine how the O&S budget isdistributed among units. In this report, the CongressionalBudget Office analyzes the structure and cost ofthe 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. CBOallocates most of the O&S budget and DoD's total numberof military personnel among major combat units-and their associated support units and overhead activities-to provide a clearer picture of the size and cost ofthe major elements of the military's force structure. Suchinformation can help policymakers evaluate proposals tochange the structure or budget of the armed forces.CBO's analysis indicates that major combat units bythemselves account for roughly one-quarter of DoD'soperation and support costs and contain about one-thirdof DoD's military personnel. Most of the rest of DoD'sO&S costs and military personnel are associated eitherwith units that support major combat units (which CBOconsiders part of the cost of maintaining fully supportedmajor combat units) or with overhead activities necessaryfor manning, equipping, and training combat and supportunits. In addition, the total operating costs associatedwith a major combat unit include a share of the costsof "defensewide" activities, such as the Defense HealthProgram, that provide various forms of administrativesupport to DoD as a whole.