3-21. Special Forces battalions and Ranger battalions may form the core of the headquarters and operational elements of a special operations task force. A special operations task force may be subordinate to a joint special operations task force, under the operational control of the theater special operations command, or any command relationship structure that best enables their mission. There may be multiple special operations task forces in a theater operating under differing command and control structures conducting missions supporting military engagement through major operations. While these task forces are not joint headquarters, they may have a variety of capabilities attached to them to enable operations or to liaise with other units. Army special operations capabilities that may be included in the task force include Psychological Operations units, Civil Affairs units, special operations aviation units, and communications, intelligence, and sustainment units from the special operations sustainment brigade. These capabilities may also include U.S. or partner nation conventional or special operations forces and interagency elements ranging from individuals to teams. The commander augments his staff with appropriate special staff officers and liaison officers taken from attached and supporting assets to integrate and synchronize all activities.