2-53. The ESC provides mission command of sustainment units in designated areas of a theater. At the theater echelon, one or more ESC’s may be attached to a TSC. An ESC may also be attached to the field Army and one assigned to the corps to act as the headquarters for the integration and synchronization of sustainment at those echelons. The ESC plans, prepares, executes, and assesses sustainment, distribution, theater opening, and reception, staging, and onward movement operations for Army forces in theater. It normally deploys when the TSC determines that a forward command presence is required. This capability provides the TSC commander with the regional focus necessary to provide effective operational-level support to Army or joint task force missions. Figure 2-3 depicts a notional AOR command and control structure of sustainment forces. See ATP 4-94 for additional information on the ESC.