Joint Region Marianas' mission is to provide installation management support to all Department of Defense components and tenants through assigned regional installations on Guam and the Northern Mariana Islands in support of training in the Marianas; to act as the interface between the Department of Defense and the civilian community; to ensure compliance with all environmental laws and regulations, safety procedures, and equal opportunity policy; and perform other functions and tasks as may be assigned.

Guam is an organized, unincorporated territory of the United States in the Micronesia subregion of the western Pacific Ocean. Guam's capital is Hagåtña, and the most populous village is Dededo. It is the westernmost point and territory of the United States, reckoned from the geographic center of the U.S. In Oceania, Guam is the largest and southernmost of the Mariana Islands and the largest island in Micronesia.