Special mission unit
The term Tier One Special Mission Unit or Special Missions Unit (SMU) is a term sometimes used, particularly in the United States, to describe some highly secretive military Special Operations Forces. Special mission units have been involved in high-profile military operations, such as the killing of Osama Bin Laden. United States. The United States military definition in the "Department of Defense Dictionary of Military and Associated Terms" comes from "Joint Publication 3-05.1 – Joint Special Operations Task Force Operations" (JP 3-05.1). JP 3-05.1 defines a "special mission unit" as "a generic term to represent  a group of operations and support personnel from designated organizations that is task-organized to perform highly classified activities." The U.S. government does not acknowledge which units specifically are designated as special missions units, only that they have special mission units within the Joint Special Operations Command (JSOC), which is part of U.S. Special Operations Command (SOC). In the early 1990s then–Commander in Chief of SOC, General Carl Stiner, identified both Delta Force and SEAL Team Six as permanently assigned special mission units in congressional testimony and public statements. In 1998, Under Secretary of Defense for Policy Walter B.  Slocombe publicly referred to special mission units during a briefing to the Senate Armed Services Committee: "We have designated special mission units that are specifically manned, equipped and trained to deal with a wide variety of transnational threats" and "These units, assigned to or under the operational control of the U.S. Special Operations Command, are focused primarily on those special operations and supporting functions that combat terrorism and actively counter-terrorist use of weapons of mass destruction (WMD). These units are on alert every day of the year and have worked extensively with their interagency counterparts." List of US SMUs . So far, only five SMUs have been publicly disclosed: Units from Special Forces, the 160th SOAR, the Aviation Technology Office (ATO), and the joint Aviation Tactics Evaluation Group (AvTEG) are controlled by JSOC when deployed as part of JSOC Task Forces such as Task Force 121 and Task Force 145. Australia. The Australian Army's elite Special Air Service Regiment is described as being a "special missions unit with unique capabilities within the Australian Defence Force". The Regiment is a component of Australia's Special Operations Command (SOCOMD), and is tasked with conducting "sensitive strategic operations, special recovery operations, training  assistance, special reconnaissance and precision strike and direct action". The SASR currently has four sabre squadrons, known as 1, 2, 3 and 4 Squadron. The first three squadrons rotate through the two roles performed by the Regiment; one squadron conducts the counter terrorism/special recovery (CT/SR) role, and the remaining squadrons conduct the warfighting/reconnaissance role, while 4 Squadron is responsible for collecting intelligence and also supports the Australian Secret Intelligence Service.