Despite the international trend towards decolonization after World War Two, the United States maintained control over the Marshall Islands throughout the Cold War. As tensions with the Soviet Union escalated, the Americans conducted a large number of nuclear experiments on the Bikini and Enewetak Atolls in order to develop an arsenal of nuclear weapons. On March 1, 1954, the United States detonated BRAVO, a 15 megaton thermonuclear weapon on the surface of Bikini. As a result of this massive explosion, hundreds of Marshallese living on the nearby atoll of Rongelap were exposed to large doses of fallout. Although the U.S. Atomic Energy Commission failed to evacuate the Rongelapese in a timely manner (they were left on their atoll for 50 hours), it moved quickly to create a research team capable of studying the exposed islanders. One week after the BRAVO test, American scientists began examinations of the Rongelapese and established a control group for comparison purposes. In 1957, the United States returned the exposed Rongelapese (and a new control group) to their contaminated atoll with the expectation that the islanders’ intake of certain radioisotopes would increase after resettlement. As Dr. Conard, the lead scientist, explained: “The habitation of these people on the island [Rongelap] … affords a most valuable ecological study on human beings … various radioisotopes can be traced from the soil, through the food chain, and into the human being.” In particular, these studies indicated significant increases in the levels of radionuclides such as Cesium 137 and Strontium 90 in the bodies of the Rongelapese. By the 1960s, when scientists started to observe high rates of thyroid cancers and other abnormalities in the exposed islanders, they concluded that the primary cause of these conditions was prolonged exposure to radioactivity. Rather than provide the afflicted Rongelapese with adequate medical care (or remove them from their contaminated atoll), the Americans continued to use them as research subjects. As a result of these medical studies, the United States gained important scientific knowledge about the immediate and long-term effects of human exposure to fallout from thermonuclear weapons. During the Cold War, the health and welfare of the Marshall Islanders was considered secondary to the geopolitical interests of the national security state.