first detonation on 1 March. Because of its high yield, SHOT/ was clearly observed by personnel located mere than three hundred miles away at Kwajalein Atoll. Furthermore, as a resuit of the evacuation to Kwajalein of natives and Air Force personnel from Rongelap, Utirik, and Rongerik due to fallout, Task Force operation- al activities became more difficult to conceal, All personnel at Kwajalein were informed by the station commander that the evacuation was to be considered as confidential. However, on 11 March, a Cincinnati newspaper printed a letter written by a transient in which his view of the detonation as seen from Kwajalein was described. A second letter revealing that Navy ships had brought the na- tive evacuees to Kwajalein also was printed. The resulting spec- ulation and Congressional inquiries forced an AEC announcement relative to the evacuation. A second result of the first detonation was the enlargement of the danger zone which meant an even greater search responsibility for the patrol ships and aircraft of TG 7.3. In short, security requirements were all-pervasive during the onsite phase. Flexibility was vital and the manhours, paper work, and the vast detail associated with fulfilling the security mis- sion proved to be a formidable portion of the CASTLE accomplish— ment. Logistical problems arising during the on-site operational phase were never sufficiently complex to cause a delay or serious disruption in the course of operations. This is not to say, how- ever, that difficulties did not arise. One of the more recurrent, 110