United States Special Operations Command
The United States Special Operations Command (USSOCOM) is a Unified Combatant Command with the mission statement
Provide fully capable Special Operations Forces to defend the United States and its interests. Plan and synchronize operations against terrorist networks.
It trains special operations personnel from all the U.S. military services, and either attaches units to geographic Unified Combatant Commands, or, when ordered to do so, may keep operational control of Special Operations units on strategic missions.
The largest part of USSOCOM is Army, but it is truly interservice; the culture is such that Special Operations is often seen as a fifth branch of the U.S. military. At one time it was a backwater and career-killer; the establishment of USSOCOM as a four-star command was a major change, and, eventually, lead to special operations officers rising to Chairman of the Joint Chiefs of Staff. As of 2007, Admiral Eric Olson is the first United States Navy SEAL] to head USSOCOM.
Joint Special Operations Command (JSOC) is a subcommand of USSOCOM, and may carry out the direct strategic role, or have a fairly independent role in a regional Unified Combatant Command. For example, in the Gulf War, there was a "white" special operations component of United States Central Command, under COL Jesse Johnson, but a "black" JSOC force operated there as well, with MG Wayne Downing commanding operations such as the "SCUD hunt". The official component had a classic role of advising foreign forces.
The existence of Army special operations is a change from the post-Vietnam War days, when a substantial amount of Special Forces was deactivated, and the Army's emphasis put on mechanized warfare. An exception was the creation of the 1st Battalion, 75th Ranger Regiment in January 1974, and the 2nd Battalion in October. These, however, were seen as elite infantry rather than special operators. 
The Army Special Operations Command is the Army component of this Unified Combatant Command. At Component headquarters, there are command and staff elements, the John F. Kennedy Special Warfare School, and various support elements. The major operational subcommands are:
- United States Army Special Forces
- 75th Ranger Regiment
- 160th Special Operations Aviation Regiment
- Ranger School
- 4th Psychological Operations Group
- 95th Civil Affairs Group
Certain Army special operations personnel are assigned to Joint Special Operations Command.
Under the Naval Special Warfare Command headquarters are the overall staff and doctrinal development, schools, the United States Navy SEALs including DEVGRU (formerly Seal Team 6), and various special warfare combat boat and other SEAL delivery units. Certain related functions, such as general Navy divers, are in other commands.
Air Force Component
The Air Force component principally provides long-range transport and fire support aircraft, but also has specialists that operate with ground special operations troops. The ground roles include air traffic control for special operations aircraft, as well as meteorological monitoring in remote areas.
Marine Corps Component
Marine Special Operations Command (MARSOC) absorbed the special reconnaissance Marine Force Reconnaissance Companies, which had reported to the corps-level Marine Expeditionary Forces (MEF). It also contains units focused on foreign internal defense, which are broadening their capabilities into other special operations missions. Force Reconnaissance Battalions, however, remain assigned to Divisions.
A Marine Special Operations School (MSOS) recruits, qualifies, ad develops Special Operations Forces (MARSOF) and has responsibility for doctrine development in Foreign Internal Defense (FID), Direct Action (DA), and Special Reconnaissance (SR). The Marine Special Operations Support Group (MSOSG) provides combat support and combat service support, the to MARSOC Units.
Going forward, the base unit of MARSOC will be the 14-man Marine Special Operations Team (MSOT), commanded by a Captain. MSOTs will be part of a Marine Special Operations Company, commanded by a Major. Each MSOC headquarters will have the same structure. All MSOCs will be elements of an MSOB, commanded by a lieutenant colonel. They will have capabilities in Unconventional Warfare (UW), Counter-Terrorism (CT), and Information Operations (IO).  This parallels the Army Special Forces structure of a 12-man Operational Detachment A (ODA) commanded by a captain, an ODB by a major, and an ODC by a lieutenant colonel.
Joint Special Operations Command
The multiservice Joint Special Operations Command (JSOC) focuses on much more secret operations than the rest of USSOCOM. It provides task forces called Special Mission Units (SMU), which often have a Ranger company attached for perimeter security. It has components from each of the service special operations commands, plus staff of its own:
- Delta Force
- Detachment from 160th Special Operations Aviation Regiment
- Air Force Special Tactics Squadron
- Thomas K. Adams (1998), US special operations forces in action: the challenge of unconventional warfare, Taylor & Francis, ISBN 0714643505, pp. 159-160
- Marine Corps Forces, Special Operations Command, Questions & Responses Page