Area of responsibility (AOR) is a pre-defined geographic region assigned to Combatant commanders of the Unified Command Plan (UCP), that are used to define an area with specific geographic boundaries where they have the authority to plan and conduct operations; for which a force, or component commander bears a certain responsibility. The term may also be used in other countries worldwide but it originated within the United States Armed Forces. This system is designed to allow a single commander to exercise command and control of all military forces in the AOR, regardless of their branch of service. The President of the United States signed the U.S. Unified Command Plan (UCP) 2008 on 17 December 2008, establishing the up-to-date boundaries for the newest Command, United States Africa Command (USAFRICOM), and all changes to boundaries of the other Commands. U.S. Unified Command Plan (UCP) 2011 was signed on 6 April 2011. Boundaries were adjusted in the high northern latitudes between USEUCOM, USNORTHCOM and USPACOM. http://www.defense.gov/news/UCP_2011_Map4.pdf Combatant commanders may designate theaters of war, theaters of operation, combat zones, and communications zones. Joint force commanders may define additional operational areas or joint areas to assist in the coordination and execution of joint warfare. The size of these areas and the types of forces used depend on the scope, nature, and projected duration of the operation. Combatant commanders and other joint force commanders use the following organization of the battlespace at the operational level of war. Combatant commanders are assigned an area of responsibility in the Unified Command Plan. Theater of war, the area of aerial, terrestrial, and naval/littoral that is, or may become, directly involved in the manner of combat; either defined by the National Command Authority or a combatant commander, This area doesn't normally encompass the combatant commander's entire area of responsibility. Theater of operations, a sub-area within a theater of war defined by the force commander required to conduct or support specific operations. Different theaters of operations within the same theater of war will normally be geographically separate and focused on different enemy forces. Theaters of operations are usually of significant size, allowing for operations over extended periods of time. Combat zone, areas required by combat forces for the conduct of operations. Communication zone, the rear part of the theater of war or theater of operations (behind but contiguous to the combat zone) that contains lines of communications, establishments for supply or