Army Security Agency
The U.S. Army has supported its fighting forces with signals intelligence since World War I. The first permanent organization to do this was established in 1930 as the Signal Intelligence Service (SIS).
In 1943 during World War II, the SIS was renamed the Signal Security Service (SSS) and quickly changed to the Signal Security Agency (SSA) and exploited the communications of both Germany and Japan, shortening the war and saving many thousands of American lives.
The SSA was reorganized as the Army Security Agency (ASA) at Arlington Hall Station, Virginia, on 15 September 1945. Operating under the command of the Director of Military Intelligence, the new agency had a sweeping charter. It exercised control functions through a vertical command structure. ASA established a worldwide chain of fixed sites field stations while maintaining large theater headquarters in the Far East and in Europe.
In 1949, all three military cryptology services were centralized under the new Armed Forces Security Agency (AFSA), the precursor of today's National Security Agency (NSA). ASA transferred most members of its large civilian headquarters staff to AFSA in this process. However, because of the need once again to support troops in actual combat in the Korean War, ASA again expanded, deploying tactical units on a large scale to support the Army in combat.
For the first time, ASA grew to include groups and battalions in its force structure. In 1955, ASA took over electronic intelligence (ELINT) and electronic warfare functions previously carried out by the Signal Corps. Since its mission was no longer exclusively identified with intelligence and security, ASA was withdrawn from G-2 control and resubordinated to the Army Chief of Staff as a field operating agency.
In the 1960s, ASA was again called upon to assist U.S. forces in the field. On 13 May 1961, the first contingent of Army Security Agency personnel arrived in South Vietnam (setting up an organization at Tan Son Nhut Air Base) to provide support to the U.S. Military Assistance Advisory Group and help train the South Vietnamese Army.
During the early years of conflict, ASA troops in Vietnam were assigned to the 3rd Radio Research Unit. Their primary mission was to locate Viet Cong transmitters operating in the south. This mission was in its early stages when one of their direction finding (DF) operators, SP4 James T. Davis, was killed in a Viet Cong ambush on a road outside Saigon. The date of the ambush, 22 December 1961, made Army Security Agent Davis the first American soldier to lose his life in combat during the Vietnam War.
The death of Davis brought home to ASA the dangers to proceeding into the jungle with short-range DF equipment to locate VC transmitters that might be only a few miles away. Since radio wave propagation in Southeast Asia required that DF equipment be very close to the transmitter, the obvious answer was to go airborne. ASA engineers began working on the problem, and by March 1962 they had their first airborne DF platform, a single-engine aircraft that flew low, slow, and had room for only two people. It had no onboard navigation system, no all-weather capability and was dependent upon visual landmarks to conduct operations The soldiers in the unit were calling it TWA (Teeny Weeny Airlines).
With the introduction of large U.S. ground combat elements into South Vietnam in 1965, the ASA organization in-country expanded. The 3rd RRU was replaced by the 509th Radio Research Group, which commanded three battalions and company-size direct support units assigned to all Army divisions. One of the 509th's subordinate battalions was the 224th Aviation Battalion (Radio Research), which pioneered in the introduction of Special Electronic Mission Aircraft (SEMA) to the battlefield
With the mission gear on board the RU-8D aircraft was known by the nicknames WINEBOTTLE, CEFISH PERSON, and CHECKMATE. These aircraft, with the on-board systems and crews, truly became the new workhorse of the Army's SEMA fleet primarily due to a combination of the improved mission gear and a newly introduced multi-engine capability, each contributing to expanding and improving the unit's mission coverage in several dimensions.
In 1968, a project known as LAFFIN EAGLE entered service with the Army and within Vietnam. It used the Army RU-21 aircraft with additionally improved mission gear to include an automated direction finding capability as a result of the use of an on-board inertial navigation system.
With the follow-on introduction of three JU-21 LEFT JAB into Vietnam, the Army now had the first airborne collection system to give 360-degree direction finding coverage. It was also the first system to use a digital computer to store calibration tables for the DF system and to calculate emitter locations from the LOBs generated by the "Spaced Loop" DF antenna and aircraft position data furnished by the on-board INS. In essence, what the RU-6A, the RU-1A, and, most importantly, the RU-8D had provided and accomplished as the Army's initial trio of signals intelligence platforms was now resident in the proliferating fleet of RU-21s in both Vietnam and CONUS.
Finally, a truly special unit was formed and deployed to Vietnam using Army pilots, Army ASA mission operators on board a Navy P-2V Neptune four-engine aircraft. This Army project was a significant leap in both mission coverage and overall mission capability. As with most of the other platforms, these aircraft were redesignated specifically as RP-2E aircraft with an associated mission project name of CEFLIEN LION or CRAZY CAT.
The remaining platforms which also contributed to the Army's airborne signal intelligence capability were six specially configured UH-1 helicopters. These aircraft were redesignated as EH-1 LEFT BANK aircraft and were assigned directly to the tactical war-fighting divisions in Vietnam. These LEFT BANK assets were manned and maintained by ASA operators, also found with the same divisions. Their flight profiles included both high and extremely low-altitude operating envelopes necessary to locate and target tactically oriented enemy threats of immediate and times-sensitive value.
Often, the ultimate customers for the information did not understand the capabilities of the systems. They expected to be able to fire bomb a given location and find the enemy at that location speaking on the radio. There were some constraints with the systems, in that the location of the target could be depicted as an elliptical core not a pinpoint target. Therefore, the transmitter was not always exactly where the report indicated resulting in friendly fire.
Radio Research Units (RRU) operated in Vietnam under the direction of the U.S. Army Security Agency (ASA) Group. During this time, these operations were classified. On 1 June 1966, the 224th Aviation Battalion (Radio Research) was activated under the command of the 509th RRG. It consisted of four companies:
• the 138th Aviation Company (RR) at Da Nang in support of I Corps tactical zone of operation
• the 144th Aviation Company (RR) at Nha Trang in support of II Corps tactical zone of operation
• the 146th Aviation Company (RR) at Saigon in support of III Corps tactical zone of operation
• the 156th Aviation Company (RR) at Can Tho in support of IV Corps tactical zone of operation
On 3 July 1967, the 1st Radio Research Company (Aviation) was assigned to the 224th Aviation Battalion (RR) to provide direct support to U.S. Military Assistance Command, Vietnam (MACV), flying six RP-2E aircraft from Cam Ranh Air Base, Vietnam, on 13-hour missions. By June 1969, the 224th Aviation Battalion (RR) with its headquarters company and five operational aviation companies had over 1,100 personnel and eighty aircraft. The battalion and the LEFT BANK elements within the two radio research companies supporting the 1st Cavalry Division and 4th Infantry Division comprised the initial fleet of the Army airborne signals capability in Vietnam.
The U-I Seminole was first introduced into the Army's inventory during the Korean War. The twin-engine aircraft was used for transportation of commanders and staff officers. ASA first used the plane as an airborne direction finding platform in Vietnam. The system became operational in January 1963. The RU-8 offered advantages over the RU-6 Beaver. For the first time, the 3rd Radio Research Unit had an all-weather capability. With its ability to carry three crew members (pilot, copilot, and intercept operator), the plane had enough room for navigational equipment. Unlike the RU-6, a crew would no longer be dependent upon visual landmarks to conduct operations.
Several ASA Army crews made the ultimate sacrifice while flying signals intelligence aerial reconnaissance missions under enemy fire. All of these were lost in the war in Southeast Asia and were the only ASA crews killed by hostile fire during the Cold War. Thirteen U.S. Army personnel were lost to hostile fire while performing the sensitive airborne intelligence collection missions. Of the thirteen, seven were U.S. Army Security Agency intercept operators and six were flight crew personnel.
Six of these thirteen are still listed as Killed in Action/Body Not Recovered. One is listed as Died While Missing/Body Recovered. The others are listed as Killed in Action. Another ASA aircraft lost in Vietnam was a LEFT BANK EH-1H assigned to the 1st Cav Division. The loss took place on 29 November 1969 near Landing Zone Buttons in Phuoc Long Province, III Corps. The mission of this crew was airborne intercept and location of enemy transmitters directly threatening the 1st Cav's area of operations. The aircraft was shot down by ground fire and destroyed by tactical airstrikes to prevent compromise of on-board mission equipment. A second LEFT BANK aircraft from the 1st Cav Division was lost on 1 March 1971 near Dambe, Cambodia (approximately twenty five miles inside Cambodia). The last ASA aircraft lost to hostile fire was a U.S. Army JU-21A LEFT JAB assigned to the 138th Radio Research Company based at Phu Bai, near the DMZ. On 4 March 1971 it took off on an intelligence-gathering mission. The aircraft headed northwest towards the DMZ between North and South Vietnam. Reportedly, the aircraft's mission was to collect intelligence regarding surface-to-air missile sites, somewhere north of the DMZ the JU-21A, tail #67-18062, was shot down.
Thank You, Jim Raab