Johnston Atoll and biological weapons testing site, a secret missile base, and a chemical weapon and Agent Orange storage and disposal site. These activities left the area environmentally contaminated and remediation and monitoring continue. The Johnston Atoll is a deserted atoll in the North Pacific Ocean located about 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. Johnston (or Kalama) Island and Sand Island are both enlarged natural features, while "Akau" (North) and "Hikina" (East) are two artificial islands formed
Enewetak Atoll cold war; in 1977–1980, a concrete dome (the Runit Dome) was built on Runit Island to deposit radioactive soil and debris. The Runit Dome is deteriorating and could be breached by a typhoon, though the sediments in the lagoon are even more radioactive than those which are contained. The U.S. government referred to the atoll as "Eniwetok" until 1974, when it changed its official spelling to "Enewetak" (along with many other Marshall Islands place names, to more properly reflect their pronunciation by the Marshall Islanders). Enewetak Atoll formed atop a seamount. The seamount was formed in the late Cretaceous. This