After the end of World War II, all the Western allies began a rapid drawdown of military forces, including those of signals intelligence. At the time, the US still had a COMINT organization split between the Army and Navy. A 1946 plan listed Russia, China, and a [redacted] country as high-priority targets.
Each service ran independent agreements with foreign counterparts, some of which, especially the British, had already formed a central communications intelligence organization (e.g., the Government Code and Cypher School at Bletchley Park, now the Government Communications Headquarters). Lack of centralization bothered these allies. The vital British-US cooperation was, at this point, one of the strongest incentives to the US Army and Navy to form a centralized organization.
US movement to centralization in SIGINT The military services formed a "Joint Operating Plan" to cover 1946-1949, but this had its disadvantages. The situation became a good deal more complex with the passage of the National Security Act of 1947, which created a separate Air Force and Central Intelligence Agency, as well as unifying the military services under a Secretary of Defense. While the CIA remained primarily a consumer, the Air Force wanted its own SIGINT organization, responsive to its tactical and strategic needs, just as the Army and Navy often placed their needs beyond that of national intelligence. The Army Security Agency (ASA) had shared the national COMINT mission with the Navy's Communications Supplementary Activity (COMMSUPACT) - which became the Naval Security Group in June 1950. During and after World War II, a portion of Army COMINT assets was dedicated to support of the U.S. Army Air Corps, and, when the independent Air Force was created in 1947, these cryptologic assets were resubordinated to the new organization as the U.S. Air Force Security Service (AFSS).
Secretary of Defense James Forrestal rejected the early service COMINT unification plans. The Department of State objected to the next draft, which put the Central Intelligence Group/Central Intelligence Agency in charge of national COMINT. On 20 May 1949, Secretary of Defense Louis Johnson created the Armed Forces Security Agency.
To centralize common services, the Armed Forces Security Agency (AFSA) as a national organisation was established by secret executive order in 1948. Still, until NSA was formed in 1952, AFSA did not have the authority for central control of individual service COMINT and COMSEC. Policy direction of COMINT came from the U.S. Communications Intelligence Board (USCIB) which, in April 1949, requested $22 million in funds, including 1,410 additional civilian employees, to expand the COMINT effort.
Pacific COMINT targeting prior to the Korean War For the Pacific, the USCIB targeted China, and Russia in both the European and Pacific theaters, but Korea was a low-priority target: On its second-tier priority list were items of "high importance"; for the month prior to the war, Japan and Korea were item number 15 on the second list, but this did not focus on Korea itself. The specific requirements were "Soviet activities in North Korea", "North Korean-Chinese Communist Relations", and "North Korean-South Korean relations, including activities of armed units in border areas."
Strategic SIGINT targeting of the USSR In the fifties, only aircraft platforms could obtain SIGINT over the USSR. A Soviet source pointed out that aircraft were of limited usefulness, due to being vulnerable to fighters and antiaircraft weapons. (Translator's estimate: in the period 1950-1969, about 15 US and NATO reconnaissance aircraft were shot down over the USSR, China, the GDR and Cuba). The US, therefore, undertook the WS-117L reconnaissance satellite project, approved by President Dwight D. Eisenhower in 1954, within which was a signal intercept subsystem under Project PIONEER FERRET. By 1959, WS-117L had split into three programs: Discoverer, the unclassified name for the CORONA IMINT satellite Satellite and Missile Observation System (SAMOS) (IMINT) Missile Defense Alarm System (MIDAS), a nonimaging staring infrared MASINT system The first experimental ELINT package would fly aboard a photoreconnaissance satellite, Discoverer-13, in August 1960. Translated from the Russian, it was equipped with "Scotop equipment was intended to record the signals of Soviet radars which were tracking the flight of American space objects."
Loss of COMINT due to a spy in NSA NSA in the post-World War II period had broken messages used by the Soviet armed forces, police and industry, and was building a remarkably complete picture of the Soviet national security posture. It was a situation that compared favorably to the successes of World War II. Then, during 1948, in rapid succession, every one of these cipher systems went dark, as a result of espionage by a Soviet agent, William Weisband. NSA suggests this may have been the most significant loss in US intelligence history.
Indochina The Viet Minh, at first, used captured French communications equipment. Under the French, no Vietnamese had been trained in cryptography, so, the initial messages were sent in the clear. On September 23, 1945, the US intercepted a message from Ho Chi Minh to Joseph Stalin, requesting aid for flood victims. This traffic immediately triggered more suspicion of Ho's relationship to Moscow, but it turned out to be one in a series of messages to world leaders.
On September 12, the Viet Minh established a Military Cryptographic Section, and, with their only reference a single copy of French Capitaine Roger Baudoin'sBaudoin French cryptographer Elements Cryptographic, and began to develop their own cryptosystems. Not surprisingly, these were very basic. By early 1946, they had established a network of radio systems, still transmitting with only minimal communications security.
The French had a number of direction-finding stations, with about 40 technicians. By 1946, the French had identified a number of Viet Minh networks and were able to do traffic analysis. They also monitored Nationalist and Communist Chinese, British, Dutch and Indonesian communications In general, however, SIGINT in French Indochina was limited by the availability of linguists.
While the US began to provide military supplies to the French, approximately at the time of the start of operations of the Armed Forces Security Agency in 1949, Indochina was a low COMINT priority. Even in 1950, the position of the French there was considered "precarious", both in a Joint Chiefs of Staff assessment and a National Intelligence Estimate.
US domestic surveillance During this period, several programs, potentially in violation of its foreign intelligence charter, the NSA (and its AFSA predecessor) monitored international telegram and selected voice communications of American citizens. Project SHAMROCK, started during the fifties under AFSA, the predecessor of NSA, and terminated in 1975, was a program in which NSA obtained copies, without a warrant, of telegrams sent by international record carriers. The related Project MINARET intercepted voice communications of persons of interest to US security organizations of the time, including Malcolm X, Jane Fonda, Joan Baez, and Martin Luther King.
Drone technology grows While there were remote-controlled aircraft in World War II, the technology of the time was inadequate for reliable operation as demonstrated by Operation Aphrodite. This began to change in 1948, when Ryan won the U.S. Air Force competition for the Q-2 jet-propelled aerial target. Known as the Q-2A Firebee, the jet-propelled target drone ground-launched by rocket and recovered by parachute was also bought by the Navy and Army.
Drones did not have an immediate SIGINT role, but they became important in later conflicts and the Firebee drone was soon to be developed into the Ryan Model 147 series which saw extensive use in the Vietnam War.
Korean War Korean coverage was incidental to Soviet and Chinese interests in the Korean Peninsula.
SIGINT gave some indications of an impending breakout prior to the beginning of the Korean War. As with the retrospective analysis of COMINT immediately after Pearl Harbor, certain traffic would have been suggestive. Before the invasion, targeting was against Chinese and Soviet targets with incidental mention of Korea. Prior to 1950 there were two COMINT hints of more than usual interest in the Korean peninsula by communist bloc nations, but neither was sufficient to provide specific warning of a June invasion.
In April 1950, ASA undertook a limited "search and development" study of DPRK traffic. Two positions the second case, as revealed in COMINT, large shipments of bandages and medicines went from the USSR to North Korea and Manchuria, starting in February 1950. These two actions made sense only in hindsight, after the invasion of South Korea occurred in June 1950.
Some North Korean communications were intercepted between May 1949 and April 1950 because the operators were using Soviet communications procedures. Coverage was dropped once analysts confirmed the non-Soviet origin of the material.
Within a month of the North Korean invasion, the JCS approved the transfer of 244 officers and 464 enlisted men to AFSA and recommended a large increase in civilian positions. In August, the DoD comptroller authorized an increase of 1,253 additional civilian COMINT positions. Given the administration's belief that the war in Korea could be part of a wider war, only some of the increase would go to direct support of the war in Korea.
COMINT, supported by information from other open and secret sources, showed a number of other military-related activities, such as VIP visits and communications changes, in the Soviet Far East and in the PRC, but none was suspicious in itself. Even when consolidated by AFSA in early 1951, these activities as a whole did not provide clear evidence that a significant event was imminent, much less a North Korean invasion of the South.
In 1952, when personnel levels and a more static war allowed some retrospective analysis, AFSA reviewed unprocessed intercept from the June 1950 period. Analysts could not find any message which would have given advance warning of the North Korean invasion. One of the earliest, if not the earliest, messages relating to the war, dated June 27 but not translated until October, referred to division level movement by North Korean forces.
Tactical SIGINT UN forces in the Korean War had an assortment of SIGINT units from the various services. On the ground, mountainous terrain, and short supplies of radios among North Korean troops, caused the 1951 reuse of World War I telephone eavesdropping techniques called Ground Return Intercept (GRI). One colonel who participated in the GRI program was heard to remark that the information was so well appreciated by his soldiers that he had little trouble getting volunteers to go out at night and implant the equipment to make intercept possible, even though the sensors might need to be as close as to the enemy.
Starting in July 1951, Low-level intercept (LLI) teams, of 2-5 men in a jeep or bunker, became popular. Although the mobile operations were productive, the jeeps were considered too vulnerable, and operations were "dug in" in bunkers near the Main Line of Resistance, as it was then called. The product was disseminated directly to combat units, usually at regimental level, and was of immediate tactical value: from twenty minutes to three days at best.
Little long-term analysis was done - or possible. It thus became difficult to keep continuity on opposing units. These problems were eased somewhat with the creation of an LLI "control section" at ASA headquarters in Seoul in late 1951. This section collated reports from the field and service as a reference source on language problems and OB questions.
Postwar changes in SIGINT, EW and ELINT