Station HYPO

The capture of Iwo Jima was a turning point in the Pacific theater, not only for its brutal combat but for its immense strategic value. Securing the island allowed U.S. forces to construct vital airstrips that immediately supported the war effort. The newly built runways enabled crippled B-29 Superfortresses returning from bombing missions over Japan to land safely, saving thousands of aircrew lives. The island also served as an essential forward base for Army Air Forces fighters—P-51 Mustangs and P-47 Thunderbolts—which could now escort B-29s deeper into Japanese territory, dramatically increasing mission success and reducing bomber losses.

The history of communication intelligence (COMINT) operations on Guam began in March 1929 with the establishment of a one-man intercept station. The first operator arrived from the recently closed Shanghai intercept site. Although the Navy Security Group (NSG) had planned to establish a station on Guam as early as June 23, 1926, those plans were never implemented, and a 1928 outline of a proposed wartime COMINT network made no mention of the island.

This after action report (AAR) provides great examples how radio intelligence provided indications and warning (I&W) to task force commanders during WWII. Throughout the report designators 8600J, 5135J and 5715J are mentioned. These designators were used to identify communications links, nets and networks that aided the intercept operators in managing the tasking, collection and exploitation of Japanese radio communication circuits.  At the end of this report list the Japanese language officers, there assignment to each of Task Force/Group and where they received the language training.  Although there were enlisted Japanese Kana Kata intercept operators on each of the ships, none are listed.

The U.S. Naval Security Group Detachment Shemya, AK, with part time Communications Technician (CT) personnel TAD from NSG Dept, NCS Adak, AK, was officially established in 1963. In 1965, the Detachment shifted to full time activation, with its own complement of CT’s. Sometime, shortly after 1968, NSG Det Shemya disestablished and closed. All personnel, assets, mission and functions were transferred to NSG Dept, NCS Adak.