2-15. An area of operations is an operational area defined by a commander for land and maritime forces that should be large enough to accomplish their missions and protect their forces (JP 3-0). The joint force land component commander, Army Service component command commander, or Army forces commander assigns subordinates AOs. Those subordinates further assign AOs from their assigned AO, down to the battalion or company echelon based on the mission variables. A unit assigned an AO may not change control measures imposed by a higher echelon headquarters within its AO. However, it may establish additional control measures to coordinate and synchronize its operations. Assigning an AO to a subordinate headquarters decentralizes execution by empowering subordinate commanders to use their own initiative to accomplish their missions. (See ADP 6-0 for more information on AO assignment.)