The United States Army is made up of three components: the active component, the Regular Army; and two reserve components, the Army National Guard and the Army Reserve. Both reserve components are primarily composed of part-time soldiers who train once a month, known as Battle Assembly or Unit Training Assemblies (UTAs), and conduct two to three weeks of annual training each year. Both the Regular Army and the Army Reserve are organized under Title 10 of the United States Code, while the National Guard is organized under Title 32. While the Army National Guard is organized, trained and equipped as a component of the U.S. Army, when it is not in federal service it is under the command of individual state and territorial governors, and the Mayor of the District of Columbia. However the National Guard can be federalized by presidential order and against the governor's wishes.
The U.S. Army is led by a civilian Secretary of the Army, who reports to the Secretary of Defense, and serves as civilian oversight for the U.S. Army Chief of Staff. The Army Chief of Staff is a member of the Joint Chiefs of Staff, a body composed of the service chiefs from each service who advise the President and Secretary of Defense on military matters under the guidance of the Chairman and Vice Chairman of the Joint Chiefs of Staff.
In 1986, the Goldwater-Nichols Act mandated that operational control of the services follows a chain of command from the President to the Secretary of Defense directly to the Unified Combatant Commanders, who have control of all armed forces units in their geographic or function area of responsibility. Thus, the Chief of Staff of each service only has the responsibility to organize, train and equip his own service component. The services provide trained forces to the Combatant Commanders for use as they see fit.
Through 2013, the Army is shifting to six geographical commands that will line up with the six geographical Unified Combatant Commands (COCOM):
- United States Army Central headquartered at Fort McPherson, Georgia
- United States Army North headquartered at Fort Sam Houston, Texas
- United States Army South headquartered at Fort Sam Houston, Texas
- United States Army Europe headquartered at Heidelberg, Germany
- United States Army Pacific headquartered at Fort Shafter, Hawaii (eventually to be merged with the Eighth Army).
- Southern European Task Force (Army component of USAFRICOM) headquartered at Vicenza, Italy
Each command will receive a numbered army as operational command, except U.S. Army Pacific, which will have a numbered army for U.S. Army forces in the Republic of Korea.
The Army is also changing its base unit from divisions to brigades. When finished, the active army will have increased its combat brigades from 33 to 48, with similar increases in the National Guard and Reserve forces. Division lineage will be retained, but the divisional HQs will be able to command any brigades, not just brigades that carry their divisional lineage. The central part of this plan is that each brigade will be modular, i.e. all brigades of the same type will be exactly the same, and thus any brigade can be commanded by any division. There will be three major types of ground combat brigades:
- Heavy brigades will have about 3,700 troops and be equivalent to a mechanized infantry or tank brigade.
- Stryker brigades will have around 3,900 troops and be based around the Stryker family of vehicles.
- Infantry brigades will have around 3,300 troops and be equivalent to a light infantry or airborne brigade.
In addition, there will be combat support and service support modular brigades. Combat support brigades include Aviation brigades, which will come in heavy and light varieties, Fires (artillery) brigades, and Battlefield Surveillance Brigades. Combat service support brigades include Sustainment brigades and come in several varieties and serve the standard support role in an army.
Regular combat maneuver organizations
The U.S. Army currently consists of 10 active divisions as well as several independent units. The force is in the process of growth, with four additional brigades scheduled to activate by 2013, with a total increase of 74,200 soldiers from January 2007. Each division will have four ground maneuver brigades, and will also include at least one aviation brigade as well as a fires brigade and a service support brigade. Additional brigades can be assigned or attached to a division headquarters based on its mission.
Within the Army National Guard and the Army Reserve there are a further six divisions, over fifteen maneuver brigades, additional combat support and combat service support brigades, and independent cavalry, infantry, artillery, aviation, engineer, and support battalion. The Army Reserve in particular provide virtually all psychological operations and civil affairs units.
|1st Armored Division||Fort Bliss, Texas||Four heavy brigade combat teams and one aviation brigade at Fort Bliss and WSMR.|
|1st Cavalry Division||Fort Hood, Texas||Four heavy brigade combat teams and one aviation brigade at Fort Hood.|
|1st Infantry Division||Fort Riley, Kansas||Two heavy brigade combat teams, one infantry brigade combat team and one aviation brigade at Fort Riley, and one infantry brigade combat team at Fort Knox, Kentucky.|
|2nd Infantry Division||Camp Red Cloud, South Korea||One heavy brigade combat team and one aviation brigade at Camp Hovey and Camp Casey, South Korea, and three Stryker brigade combat teams (SBCTs) at Fort Lewis, Washington.|
|3rd Infantry Division||Fort Stewart, Georgia||Two heavy brigade combat teams and one infantry brigade combat team at Fort Stewart, Georgia, one heavy brigade combat team at Fort Benning, Georgia, and one aviation brigade at Hunter Army Airfield, Georgia.|
|4th Infantry Division||Fort Carson, Colorado||Three heavy brigade combat teams and one infantry brigade combat team at Fort Carson, Colorado.|
|10th Mountain Division||Fort Drum, New York||Three infantry brigade combat teams and one aviation brigade at Fort Drum and one infantry brigade combat team at Fort Polk, Louisiana.|
|25th Infantry Division||Schofield Barracks, Hawaii||Two brigade combat teams and one aviation brigade at Schofield Barracks (one infantry and one Stryker), one Stryker brigade combat team at Fort Wainwright, Alaska, and one airborne infantry brigade combat team at Fort Richardson, Alaska.|
|82nd Airborne Division||Fort Bragg, North Carolina||Four airborne infantry brigade combat teams and one aviation brigade at Fort Bragg.|
|101st Airborne Division||Fort Campbell, Kentucky||Four infantry brigade combat teams (air assault) and two aviation brigades at Fort Campbell.|
|170th Infantry Brigade (Mechanized)||Baumholder, Germany||activated July 2009.|
|172nd Infantry Brigade||Grafenwöhr, Germany||Two mechanized infantry battalions, one M1A1 Abrams battalion, one self-propelled 155mm field artillery battalion, one combat engineer battalion.|
|173rd Airborne Brigade Combat Team||Vicenza, Italy||Two airborne infantry battalions, one cavalry squadron, one airborne field artillery battalion, one special troops battalion, and one support battalion.|
|2nd Cavalry Regiment||Vilseck, Germany||6 subordinate Squadrons: 1st (Stryker Infantry), 2nd (Stryker Infantry), 3rd (Stryker Infantry), 4th (Recon, Surveillance, Target Acquisition), Fires (6x3 155mm Towed Arty), & RSS (Logistical Support); 5 Separate Troops/Companies: Regimental Headquarters Troop, Military Intelligence Troop, Signal Troop, 84th Engineer Company, and Anti-Tank Troop.|
|3rd Armored Cavalry Regiment||Fort Hood, Texas||Three tank squadrons, one aviation squadron, and one support squadron.|
|11th Armored Cavalry Regiment||Fort Irwin, California||Serves as the Opposing Force (OPFOR) at the National Training Center (NTC). Multi-compo HBCT.|
 Special Operations Forces
US Army Special Operations Command (Airborne):
|Name||Headquarters||Structure and purpose|
|Special Forces (Green Berets)||Fort Bragg, North Carolina||Seven groups capable of unconventional warfare, foreign internal defense, special reconnaissance, direct action, and counter-terrorism.|
|75th Ranger Regiment (Rangers)||Fort Benning, Georgia||Three battalions of elite light airborne infantry.|
|160th Special Operations Aviation Regiment (Night Stalkers)||Fort Campbell, Kentucky||Four battalions, providing helicopter aviation support for general purpose forces and Special Operations Forces.|
|4th Psychological Operations Group||Fort Bragg, North Carolina||Psychological operations unit, six battalions.|
|95th Civil Affairs Brigade||Fort Bragg, North Carolina||Civil affairs brigade.|
|528th Sustainment Brigade (Special Operations) (Airborne)||Fort Bragg, North Carolina|
|1st SFOD-D (Delta Force)||Fort Bragg, North Carolina||Elite special operations and counter-terrorism unit. Its operators are chosen carefully from the best soldiers of the Army Special Operations Forces and other SOCOM units. Most information about the unit is classified. Based on the B|