Johnston Atoll, also known as Kalama Atoll to Native Hawaiians, is an unincorporated territory of the United States currently administered by the United States Air Force of the United States Department of Defense. Johnston Atoll is an uninhabited 1,300 ha (3,200 acres) atoll in the North Pacific Ocean located about 750 nmi (860 mi; 1,390 km) southwest of the island of Hawai'i and is grouped as one of the United States Minor Outlying Islands. The atoll, which is located on a coral reef platform, has four islands.