Johnston Island Air Force Base is a former United States Air Force base on the Johnston Atoll in the United States Minor Outlying Islands, in the Pacific Ocean several hundred kilometers southwest of Hawaii. After its closure, it briefly operated as Johnston Atoll Airport, until that also closed in 2005.
Johnston Atoll is an unincorporated territory of the United States, under the jurisdiction of the United States Air Force (USAF). The island is closed to public entry, and limited access for management needs is only granted by a letter of authorization from the USAF. A special use permit is also required from the United States Fish and Wildlife Service (USFWS) to access the island by boat or enter the waters surrounding the island, which are designated as a National Wildlife Refuge and part of the Pacific Islands Heritage Marine National Monument. The Johnston Atoll National Wildlife Refuge extends from the shore out to 12 nautical miles, continuing as part of the National Wildlife Refuge System out to 200 nautical miles. The Pacific Remote Islands Marine National Monument extends from the shore out to 200 nautical miles.
The isolated atoll has been under the control of the U.S. military since 1934. During that time, it was variously used as a naval refueling depot, an airbase, a testing site for nuclear and biological weapons, a secret missile base, and a site for the storage and disposal of chemical weapons and Agent Orange. Those activities left the area environmentally contaminated. The USAF completed remediating the contamination in 2004 and performs only periodic monitoring today.