Starting in the late 1940s, Johnston Atoll played an important role in the United States' nuclear testing program. From the late 1950s to 1962, high-altitude nuclear testing was carried out at Johnston Atoll. Chemical munitions were also stockpiled on Johnston and subsequently incinerated in the Johnston Atoll Chemical Agent Disposal System, built in 1990 and disassembled in 2004 after completion of its mission. By May 2005, almost all of Johnston Island's infrastructure had been removed, and all personnel left the atoll, including refuge staff.
Today, the emergent land at Johnston Atoll remains under the jurisdiction of the U.S. Air Force. Refuge staff occasionally visit the atoll to monitor the status of its wildlife. While previously most of the seabirds and shorebirds were found on Sand, Akua (North), and Hikina (East) islands, they have now colonized Johnston Island, taking advantage of the trees and shrubs left behind by its former human residents.
Since August 2010, Johnston Atoll has been a focus of attempts to improve our understanding of yellow crazy ant ecology and its impacts on wildlife while developing effective eradication techniques. Staff and volunteers work to eradicate the invasive ant. In addition to maintaining pesticide bait stations, duties include monitoring and enforcement of quarantine measures, monitoring ant and bird populations, and camp maintenance.