Station CAST was the United States Navy signals monitoring and cryptographic intelligence fleet radio unit at Cavite Navy Yard in the Philippines, until Cavite was captured by the Japanese forces in 1942, during World War II. It was an important part of the Allied intelligence effort, addressing Japanese communications as the War expanded from China into the rest of the Pacific theaters. As Japanese advances in the Philippines threatened CAST, its staff and services were progressively transferred to Corregidor in Manila Bay, and eventually to a newly formed US-Australian station, FRUMEL in Melbourne, Australia. STATION CAST had originally been located at Shanghai but had been evacuated to Cavite in early 1941 as part of the US Navy's disengagement with China. Prior to the war, CAST was the US Navy's Far East cryptographic operation, under the OP-20-G Naval Intelligence section in Washington. It was located at the Navy Yard in Manila and moved into the tunnels on Corregidor, as Japanese attacks increased. STATION CAST possessed one of the PURPLE machines produced by the US Army. Cryptanalytic problems facing the United States in the Pacific prior to World War II were largely Japanese. An early decision by OP-20-G divided responsibility for Japanese cryptanalysis amongst its various stations. Station CAST (at Manila in the Philippines), Station HYPO (Pearl Harbor, Hawaii) OP-20-02, and OP-20-G itself in Washington, shared cryptanalytic duties. Other Stations (on Guam, in Puget Sound on Bainbridge Island, etc.) were tasked and staffed for signals interception and traffic analysis. PURPLE diplomatic traffic The US Army SIS break into the highest security Japanese diplomatic cypher (called PURPLE by US analysts) produced very interesting intelligence, but little of military value (except for Ambassador Hiroshi Oshima's despatches from Germany); none of tactical value, and not much more of direct political value as the Foreign Office in Japan was thought by the ultra-nationalists in effective charge of Japanese foreign and military policy, to be unreliable. Furthermore, decrypts from PURPLE traffic, eventually called MAGIC, were rather capriciously distributed to high level officials in Washington, and in general, poorly used. SIS was able to build several PURPLE machine equivalents and the distribution of those machines has since been thought controversial. One was sent to Station CAST. After the US entered the War, two went to Bletchley Park, the center of British cryptographic work. One was sent to the Far East Combined Bureau (FECB) at Singapore, and was lost