Eighth United States Army (EUSA)

The mission of the Eighth United States Army (EUSA) is to support deterrence of North Korea aggression against the Republic of Korea (ROK). Should deterrence fail, Eighth United States Army would support Non-combatant Evacuation Operations (NEO), transition to hostilities, generate combat power to support the Commander in Chief UN Command (UNC)/Combined Forces Command's (CFC) campaign, and provide combat support and combat service support to assigned, attached, and other designated forces within the Korea Theater of Operation and on order, conduct combat operations.

Eighth US Army provides forces to the Commander in Chief of United Nations Command; United States Forces, Korea; and Republic of Korea/US Combined Forces Command. In time of war it would undertake combat, combat support and combat service support operations as directed, and also support the Combined Forces Command and Ground Component Command on the Korean peninsula.

During the 1990s, nowhere in the US Army were rotation times shorter than in Korea. Normal US military tours of duty could range from 2 to 3 years, and some military experts felt that even that time interval was inadequate to develop long-term unit cohesion. US policy required that virtually all personnel rotate out of Korea after 12 months. Worse, positional turnover, the turnover in terms of assigned responsibilities, approached 125 percent annually. Ironically, annual turnover among Japan-based personnel in 1950 was 43 percent, a "high" rate blamed for the unit's poor showing in the first days of the Korean conflict. Given that unit cohesion was largely a function of personnel working together over time, the much-maligned divisions stationed in Japan in 1950 arguably retained greater cohesion than the 2nd Infantry Division, for instance, did almost 50 years later.

On 16 March 1998, the Eighth US Army became the newest service component command for the commander in chief UNC/CFC/US Forces Korea (USFK). The new Army Service Component Command (ASCC), placed within the Ground Component Command, joined the Air Force, Navy, Special Operations, and Marine Corps Component Commands to give the CINC UNC/CFC/USFK more options and capabilities during armistice and all phases of a campaign plan. As the Army war fighting headquarters for the Korean peninsula, ASCC presented the CINC a set of relevant and complementary capabilities. This would allow the CINC to consider all options available and to tailor campaign plans to best meet the military objective of the mission.

The mission of the new ASCC was threefold. First, it was the Army's supporting force. In this capacity, the ASCC organized, equipped, trained, maintained, and supported the Army and other forces under the "Common Items of Support" requirement. Secondly, it served as an Army combat force. In this role, the ASCC employed Army forces, selected forces and advised on the use of the Army. Thirdly, the service component commander established linkage to the joint war fighting commander and took specified part in the Unified Armed Action Force and the Unified Command Plans. In Korea, as part of the CFC coalition, the ASCC was assigned combat functions that required immediate readiness. Conditions demanded that in-place forces be ready to respond and perform at a moment's notice. Should conditions demand the deployment or employment of US Army forces, the CINC would do so through the Army Component Commander in Korea.

The Army service component served as the senior Army echelon in a theater and is the Army service component command of a unified command. It included the service component commander and all Army personnel, organizations, units, and installations that were assigned to the unified command.

The Korean Augmentation to the United States Army (KATUSA) Soldier Program was initiated in July 1950 by an informal agreement between the Honorable Syngman Rhee, President of the Republic of Korea, and General of the Army Douglas MacArthur, Commander in Chief, United Nations Command. The concept of this program originally was to augment the United States fighting forces just after the outbreak of the Korean War. After the armistice, KATUSA soldiers remained with US units to receive training that was not readily available in the ROK Army and to enhance the US Army's mission capability. The KATUSA Soldier Program had been a continuous since 1950 with only periodic strength adjustments dictated by requirements. Originally, the KATUSA soldiers were returned to the ROKA after serving with the US Army. After 1968, however, KATUSA soldiers remained with the US Army until their service commitments were completed. The objective of the KATUSA Soldier Program was to augment US forces with ROK Army soldiers in order to increase the ROK/US combined defense capability on the Korean peninsula. The KATUSA Soldier Program was significant not only because of the military manpower and monetary savings that it provided to the U.S. Army, but also because it represented ROK/US cooperation and commitment to deter war. The KATUSA Soldier Program was also symbolic of ROK/US friendship and mutual support.

On 16 October 2006, Eighth US Army was designated as an ASCC to USFK, a subunified command of the United States Pacific Command (USPACOM). As such, Eighth US Army reported directly to Headquarters, Department of the Army. Eighth US Army was an operational-level Army Force designated by the Secretary of the Army as the ASCC of USFK and exercised administrative control authority and responsibility on behalf of the Secretary of the Army and exercises operational control over Army Forces, as delegated by the Commander, USFK, throughout the USFK area of responsibility.

On 23 January 2012, Eighth US Army was discontinued as an Army Service Component Command to the United States Forces Korea (USFK) and was redesignated and assigned as an operational-level Field Army Headquarters and subordinate command of the United States Army Pacific. Eighth US Army would exercise operational control of Army Forces, as delegated by the Commander, United States Pacific Command (USPACOM) through Commander, USFK or Commander, Korea Command (KORCOM) if and when USFK transitioned to KORCOM.

On 31 July 2012, the Eighth Army Commanding General Lieutenant General John D. Johnson released a roadmap called "How We Fight" to outline a revolutionary mission change as part of the shift in focus on the part of the United States Military to the Asia-Pacific region. The guidance highlighted the danger posed by North Korea and the potential for sudden regime instability, potential environmental disaster, humanitarian crisis, and the threat of WMD weapons. It also noted the strength and continued need for the US-ROK alliance to counter the threat posed by North Korea and otherwise provide regional stability. At base, the guidance indicated that Eighth US Army had fundamentally changed from its previous role as an Army Service Component Command to a headquarters that commanded and controled a war-fighting US-ROK Combined Joint Task Force (CJTF). This change was revolutionary in scope and Lieutenant General Johnson indicated that it would require significant modifications in training, maintaining, and equipping the combat force in Korea and how those decisions were made. The transition would shape all aspects of how the US Army in Korea thought, lived, and fought according to Lieutenant General Johnson's guidance. Importantly, Eighth US Army possessed skills, unique capabilities, and a mission, that required the conduct of decisive land operations in a Chemical, Biological and Nuclear environment; and to combat the threat of Weapons of Mass Destruction while simultaneously, serving as the Korea Theater of Operations Army Forces (ARFOR) command.

On 25 July 2013, Eighth US Army established the 2503rd Digital Liaison Detachment to serve as the primary link with the Republic of Korea Ground Component Command. The 2503rd Digital Liaison Detachment would be able to conduct 24-hour operations if necessary. The detachment would strengthen the ROK-US Alliance by providing support, assistance, and advice to the ROK Ground Component Command on all aspects of US Army warfighting forces.