The Air Force (O & M) appropriation is the underpinning of readiness and sustainability. Approximately 85% of the O and M budget is for fixed, must- pay bills such as flying hours and training, weapon system support and maintenance, deployments, space launches, scheduled equipment and facility maintenance, civilian pay, utility expenses, and contract operations. These cannot be reduced in the short term. Financial requirements in the O and M appropriation are dictated by programmed force structure levels and activity rates. Within this appropriation, there is critical balance. O and M resources must be sufficient to support the force structure and to sustain a mission ready force of existing weapon systems as well as field new or modernized systems on schedule. It must be balanced, affordable and executable given the mission objectives and taskings. Narrative Justification is detailed by the following activity groups: Strategic forces; General purpose forces; Intelligence and communications; Airlift; Central supply and maintenance; Training, medical and other personnel activities; Administration and associated activities; Support of other nations; and Special operations forces.