Project 4.1 was the designation for a medical study and experimentation conducted by the United States of those residents of the Marshall Islands exposed to radioactive fallout from the March 1, 1954 Castle Bravo nuclear test at Bikini Atoll, which had an unexpectedly large yield. Government and mainstream historical sources point to the study being organized on March 6 or March 7, 1954, six days after the Bravo shot. Establishment and secrecy In the wake of the Castle Bravo detonation, a new research section was added to the Castle Bravo Weapons Effects research section. Program 4, "Biomedical effects," was to include one project, Project 4.1, titled "Study of Response of Human Beings exposed to Significant Beta and Gamma Radiation due to Fall-out from High-Yield Weapons." Eugene P. Cronkite of the National Naval Medical Center was designated as Project Officer. Cronkite's instructions stressed the importance of secrecy surrounding the project: The purpose of the project, as a 1982 Defense Nuclear Agency report explained, was both medical as well as for research purposes: Preparation As a Department of Energy Committee writing on the human radiation experiments wrote, "It appears to have been almost immediately apparent to the AEC and the Joint Task Force running the Castle series that research on radiation effects could be done in conjunction with the medical treatment of the exposed populations." The DOE report also concluded that "The dual purpose of what is now a DOE medical program has led to a view by the Marshallese that they were being used as 'guinea pigs' in a 'radiation experiment.'" Organizations involved in the project included the Naval Medical Research Institute, the Naval Radiological Defense Laboratory, Patrol Squadron 29, the Naval Air Station, Kwajalein, Los Alamos National Laboratory, the Applied Fisheries Laboratory at the University of Washington, and Hanford Atomic Power Operations. Three U.S. Navy ships were used in the project: USS Nicholas, USS Renshaw, and USS Philip. The primary study of the Marshallese was terminated around 75 days after the time of exposure. In July 1954 a meeting at the Division of Biology at the U.S. Atomic Energy Commission decided to complete 6- and 12-month follow-up exposure studies, some of which were later written up as addendums to Project 4.1. Intentionality Some Marshallese have alleged that the exposure of the Marshallese was premeditated. In 1972, Micronesian Representative Ataji Balos charged at the Congress of Micronesia that the exposure during