The United States Forces Korea (USFK) is a sub-unified command of U.S. Indo-Pacific Command (USINDOPACOM). USFK is the joint headquarters for U.S. combat-ready fighting forces and components under the ROK/US Combined Forces Command (CFC) – a supreme command for all of the South Korean and U.S. ground, air, sea and special operations component commands. Major USFK elements include U.S. Eighth Army (EUSA), U.S. Air Forces Korea, U.S. Naval Forces Korea (CNFK), U.S. Marine Forces Korea (MARFORK) and U.S. Special Operations Command Korea (SOCKOR). It was established on July 1, 1957.

A unified combatant command, also referred to as a combatant command (CCMD), is a joint military command of the United States Department of Defense that is composed of units from two or more service branches of the United States Armed Forces, and conducts broad and continuing missions. There are currently 11 unified combatant commands, and each is established as the highest echelon of military commands, in order to provide effective command and control of all U.S. military forces, regardless of branch of service, during peace or during war time. Unified combatant commands are organized either on a geographical basis or on a functional basis, e.g., special operations, force projection, transport, and cybersecurity. Currently, seven combatant commands are designated as geographical, and four are designated as functional. Unified combatant commands are "joint" commands and have specific badges denoting their affiliation.