2-44. A phase is a planning and execution tool used to divide an operation in duration or activity. A change in phase usually involves a change of mission, task organization, or rules of engagement. Phasing helps in planning and controlling, and it may be indicated by time, distance, terrain, or an event. The ability of Army forces to extend operations in time and space, coupled with a desire to dictate tempo, often presents commanders with more objectives and decisive points than the force can engage simultaneously. This may require commanders and staffs to consider sequencing operations.