commands are established by combatant commanders when authorized by the Secretary of Defense through the Chairman of the Joint Chiefs of Staff to conduct operations on a continuing basis in accordance with the criteria set forth for unified commands. They may be established on a geographic area basis such as U.S. Forces Japan or on a functional basis such as Special Operations Command, Pacific.

Subordinate Unified Commands

Explanation:

Based on the description provided it can be said that the term being mentioned are Subordinate Unified Commands. Like mentioned, these are technically military command issued by the US Department of Defense and are composed of units from two or more service branches in order to conduct continuing missions. These commands are created to conduct a portion of the mission or tasking of their parent geographic or functional command.