by Lieutenant Colonel Robert L. Turkoly-Joczik, Ph.D. (USA, Retired)

Of the many military activities reported during the Second Indochina War, little has been written about the United States cross-border ground reconnaissance operations conducted in Laos and Cambodia. Despite this absence of data, the participation of the U.S. Military Assistance Command Vietnam’s (MACV) Studies and Observation Group (SOG), and its ground reconnaissance component, Operations 35 (OPS-35), in strategic intelligence gathering is a historical fact. Although little has been written about the SOG and its troops, a picture of the unit’s activities can be reconstructed and studied from several of the verbal and written sources that have been made public.1

OPS-35 Mission and Composition

In keeping with security practices that required compartmentalization for classified activities, SOG’s ground reconnaissance element OPS-35 was, but one of its many secret component forces. Other components such as OPS-31, 32, 33 and 34 were responsible for conducting other unconventional and conventional warfare activities such as psychological operations (PSYOPS), maritime operations, and the training and direction of agent-operatives destined for infiltration into North Vietnam.

The conduct of cross-border ground reconnaissance and its incumbent intelligence requirements were the purview of OPS-35. In addition to this mission, OPS-35’s task also included locating and freeing friendly personnel captured or missing in action, assisting in the conduct of PSYOPS, and performing other tasks such as prisoner apprehension and equipment retrieval. The subordinate agencies within OPS-35 responsible for the conduct of these activities were its three field elements: Command Control North (CCN), Command Control Central (CCC), and Command Control South (CCS) located at Danang, Kontom, and Ban Me Thuot.

To provide anonymity for the organization and its personnel, OPS-35 had an administrative affiliation with the U.S. Army’s 5th Special Forces Group (Airborne) (5th SFGA).2 Under this arrangement all of the OPS-35’s U.S. Army personnel were listed on the 5th SFGA’s rolls. The affiliation was a convenient cover for their personnel since most of the members of OPS-35 had served in the 5th SFGA during earlier tours of service in South Vietnam. Just as OPS-35’s American personnel had an earlier affiliation with the 5th SFGA, so had its Asian mercenary force, usually with the Civilian Irregular Defense Group (CIDG), the Mobile Strike Force (MSF) (sometimes called the Mike Force), or the Mobile Guerrilla Force (MGF). There always appeared to be a special category of men who, in the words of one U.S. Army officer, “repeatedly sought out the tough and dangerous work with the Mike Forces (MSF), the special projects and the classified missions (SOG).”3 Therefore it would seem that the transition from duty with the CIDG to the classified and dangerous missions conducted by the SOG was a rite of passage.

Between 1964 and 1972, the SOG’s OPS-35 was said to have had a strength of 2,000-2,500 U.S. personnel and 7,000 to 8,000 indigenous troops, most of whom came from South Vietnam’s Montagnard, Cambodian (Khmer Krom), and Nung ethnic minorities. Although OPS-35’s primarily concerns were with strategic reconnaissance, on special occasions its teams would conduct raids, prisoner apprehension missions, or seek-locate-annihilate-and-monitor (SLAM) missions.4 Frequently the teams were sent into Laos to the home villages of ethnic minority team members to induce the villagers to aid in establishing “in country” bases for future operations. On other occasions, their task was to tap North Vietnamese Army (NVA) telephone lines or to plant acoustic and seismic sensors along the Ho Chi Minh Trail.

Leaping Lena and Prairie Fire Operations

The first series of U.S.-sponsored cross-border operations took place in 1964 under the code name “Leaping Lena.” The South Vietnamese Government under the supervision of the Central Intelli- gence Agency (CIA) conducted these activities. Unfortunately, Leaping Lena was a failure and was terminated.5 When created in 1964, the SOG benefited from the Leaping Lena experiences and established a policy that called for the use of both indigenous and U.S. personnel for operations conducted in Laos and Cambodia. An analysis of the Leaping Lena operations had shown that if a team was to accomplish its mission and meet the high standard of intelligence- gathering and reporting required by the SOG, it would have to be with U.S. supervision and leadership. The presence of the U.S. personnel on the teams insured accurate and reliable intelligence.

The Montagnards of Vietnam’s Central Highlands were especially helpful in the cross-border operations since their tribal affiliations crossed international boundaries. This factor was particularly useful when the OPS-35 teams conducted patrols in Laos and northern Cambodia, both countries having sizable Montagnard populations along the South Vietnamese border. To a lesser degree, Cambodians born in South Vietnam (called Khmer Krom) fulfilled the same purposes when SOG conducted operations in certain regions of Cambodia. At one SOG site (Hobarge Tours), an entire reaction company of Khmer Krom was never to participate in an operation in Cambodia according to official policy. Official policy notwithstanding, Khmer Krom troops may have engaged in OPS-35’s cross-border operations just as they did in other unconventional activities. Another of the minority groups used by OPS-35 in its cross-border operations was the Nungs, mercenaries who were one of the most effective of all the ethnic-minority paramilitary forces.

To provide the SOG and the United States some form of plausible denial (albeit weak) for personnel who might be captured, the SOG units frequently had maps printed with distorted international boundary lines. In a further effort to conceal the nature of its operations, it was SOG’s policy to report its casualties as having occurred in South Vietnam. To ensure operational security, American personnel conducted the planning activities for OPS-35. The OPS-35 element had no counterpart relationship like that between the 5th SFGA and the Vietnamese Special Forces, Lac Luong Dac Biet (LLDB).

The name of the first series of SOG patrols into Laos was “Shining Brass” (later renamed “Prairie Fire”) conducted between 1965 and 1969. These patrols began when intelligence reports indicated that the Ho Chi Minh Trail was expanding to meet the increasing demand for men and material in the South.6 To determine the nature and location of these activities in Laos, the OPS-35 forces conducted reconnaissance missions with units known as “Spike Teams” comprising six to twelve men (two to four U.S. personnel and four to eight indigenous personnel).

The U.S. Congressional Record of September 1973 revealed the increasing frequency of Prairie Fire missions when it disclosed that between September 1965 and April 1972, SOG conducted 1,579 reconnaissance patrols, 216 platoon-sized patrols, and three multi-platoon-sized operations in Laos.7 These missions deployed from U.S. Special Forces CIDG camps such as Kham Duc, Khe Sanh, and Kontum. The camp at Khe Sanh was particularly valuable. It was an important facility that regularly supplied vital information on North Vietnamese activity in Laos.

The North Vietnamese did not overlook the importance of Khe Sanh. They were well aware of the patrols sent into Laos to monitor their activities. In 1968, North Vietnamese forces had nearly overrun Khe Sanh and Kham Duc. From these and other camps along the border, American-led teams of Indochinese mercenaries regularly infiltrated into Laos. These units had assigned missions in zones that extended 20 kilometers into the Laotian interior. The terrain in these areas was extremely difficult, and they measured their movement in meters not kilometers. Using the least accessible regions as points of infiltration enabled the OPS-35 teams to enter the target areas with less chance of discovery by enemy patrols. After a team had infiltrated the area, it then moved to its specific reconnaissance site. Occasionally the team monitored its target for as long as ten days in order to gather maximum intelligence.

To support its ground reconnaissance activities, the SOG maintained a communications site 20 kilometers inside the Laotian border. The teams used the outpost to transmit and relay messages between launch sites and the teams in the Laotian countryside.8 The site’s radio capability permitted the SOG teams to conduct their missions at the extreme limits of their 20-kilometer target zones and still have communication with the OPS-35 command, regardless of the terrain and distance. With the extended communications capability the teams could call on fighter bombers to engage targets of opportunity anywhere in the operational area, and it permitted the teams to call for extraction when they were in a tenuous situation.

Although there are no available records that indicate which of the Indochinese ethnic groups constituted the largest portion of SOG’s mercenary force, it is likely that the Montagnards comprised the majority of the indigenous personnel. Montagnard mercenaries were regularly employed on SLAM operations.9 These operations were risky affairs that frequently brought heavy casualties to friends and foes alike.10 In September 1970, 150 indigenous troops and 10 U.S. SOG personnel infiltrated into Laos near the Ho Chi Minh Trail with the mission of luring several NVA battalions into an area where fighter-bomber aircraft could attacked them. The operation was a success and allegedly, the Communist forces lost 500 men killed in the battle. The SOG force lost a dozen men killed and 40 to 50 others wounded. The New York Times reported the details of the action and revealed, for the first time, that the United States was conducting secret military operations in Laos. The article noted that the Department of Defense (DOD) had denied that such activities were taking place and had declared, “There are no United States ground troops in Laos.”11 Four months later these same sources admitted that reconnaissance teams were operating inside Laos...“but only in an intelligence-gathering role.”12

Salem House Operations

Concurrent with the Prairie Fire operations were the SOG’s missions in northeastern Cambodia. These operations, originally named “Daniel Boone,” were later redesignated “Salem House.” These missions provided intelligence on North Vietnamese and Viet Cong bases located in Cambodia. Another objective of the Salem House operations was to determine the level of Cambodian Government support for the NVA and Viet Cong.13

The Salem House operations had a number of restrictions that affected their activities in Cambodia. Many of the restrictions were modified or withdrawn and new restrictions imposed; the pattern of change in the restrictions presents an interesting picture of the war’s development in Cambodia. In May 1967, the Salem House missions were subject to the following restrictions:

By October 1967, SOG’s teams had permission to infiltrate the entire Cambodian border area to a depth of 20 kilometers. However, their helicopters were only permitted ten kilometers inside Cambodia. In December, the DOD, with the Department of State’s concurrence, approved the use of Forward Air Controllers (FACs) to support SOG operations. The FACs had authorization to make two flights in support of each Salem House mission.


In October 1968, SOG teams received permission to emplace self-destructing land mines in Cambodia. The following December, the depth of penetration into northern Cambodia was extended to 30 kilometers; however, the 20-kilometer limit remained in effect for central and southern Cambodia. The final adjustment in Salem House operations made in 1970 during the incursion into Cambodia permitted reconnaissance teams to operate 200 meters west of the Mekong River (an average distance of 185 kilometers west of the South Vietnamese border). However, the SOG reconnaissance teams never ventured that far west, due to the lift and range limitations of their UH-1F helicopters. Thus from the initiation of SOG’s Cambodian operations in 1967 until 1970, there was a progressive expansion of the zones of operation and OPS-35 patrols within Cambodia. The enlargement of the areas of operation and the increasing number of Salem House missions, gives an indication of how seriously the Johnson and Nixon Administrations viewed the NVA’s use of Cambodian base areas. It was also indicative of the U.S. military’s growing awareness of the role of the Central Office for South Vietnam (COSVN) and its deleterious effect on the war in South Vietnam.15

From 1967 through April 1972, OPS-35 conducted 1,398 reconnaissance missions, 38 platoon-sized patrols, and 12 multi-platoon operations in Cambodia. During the same period, it captured 24 prisoners of war.16

Deactivation of SOG and Congressional Hearings

In mid-1972, SOG deactivated. Despite this fact, its cross-border program came under attack in 1973 from the U.S. press and the U.S. Congress. Newspapers such as The New York Times and the Saint Louis Post-Dispatch indicated that despite the prohibitions imposed by the Foreign Assistance Act of 1971, U.S. military personnel had participated in cross-border operations in Cambodia during 1972. This revelation also indicated that the House of Representatives and the Senate Appropriations Committee had had briefings on the SOG’s activities, functions, and casualties since 1966. A series of Congressional hearings held in 1973 also revealed that the Senate Foreign Relations Committee’s Subcommittee on U.S. Security Agreements and Commitments Abroad had also known of the SOG’s activities, costs, and casualties. The Congressional hearings disclosed that the SOG’s Top Secret budget was in the U.S. Navy budget NOP 345, carried as a classified project.17

The focus of the Congressional inquiry was the military’s disregard of the Foreign Assistance Act and the War Powers Act, which forbade the use of U.S. advisers or US. funds to support our ground forces in countries that bordered South Vietnam. Several witnesses gave testimony that they had participated in operations in Cambodia during 1972, evidence that supported the charge that the Acts had been violated.18 Other than disclosing the fact that the SOG and the U.S. Government had conducted covert operations in Cambodia in violation of Congressional legislation, the hearings did little to end the war in South Vietnam or to ease its trauma in the United States. The entire maneuver was a political exercise between the congressional doves and hawks; it had little constructive value.

Assessing the SOG’s  Contributions

It is difficult to make a complete assessment of the SOG’s contributions to the Vietnam war effort. However, from the data that is available, such as the U.S. Congressional Record, comments from SOG veterans, and in the remarks of a North Vietnamese journalist, one can attempt some analysis.

The NVA journalist, Tran Mai Nam, indicated that the NVA had a particular dread of the “unpredictable brushes with the enemy’s Special Forces” and was concerned about capture on the Ho Chi Minh Trail by “commando raids.”19 However, the fear and stress exhibited by NVA troops cannot form the sole basis for an evaluation of the SOG. One U.S. Department of Defense document that does comment on the SOG’s activities is A Study of Strategic Lessons Learned in Vietnam. The study indicates that—

SOG operations provided a considerable amount of intelligence data to Washington and Saigon on North Vietnamese troop movements along those portions of the Ho Chi Minh Trail that were patrolled by the OPS-35 forces. Because of these reconnaissance efforts, U.S. planners had a fairly clear picture of enemy forces in the sanctuaries and along the trail by early 1969.20

Another factor to consider in evaluating OPS-35’s operations in Laos and Cambodia were the political constraints that determined what they could do. The Prairie Fire operations were always subject to the approval or disapproval of the U.S. Ambassador in Laos, William H. Sullivan.21 Sullivan’s behavior and actions earned him some enmity from the U.S. military, and he was frequently referred to as “the field marshal.” General William Westmoreland noted an example of the difficulties experienced with the Ambassador when he said, “Bill Sullivan had a tendency to impose his own restriction[s] over and above those laid on by the Department of State. (We sometimes referred to the Ho Chi Minh Trail as Sullivan’s Freeway).22 Regarding Ambassador Sullivan and the SOG’s operations in Laos, one U.S. Special Forces officer commented that “often when intelligence would develop leads suggesting operations into certain areas, requests for authority to insert teams would be denied on the grounds that the CIA had teams in the area.23 When asked for a report on the area of interest, the CIA and Sullivan gave the SOG nothing. Sullivan’s concern about the SOG’s operations stemmed from his desire to ensure that civilians did not become casualties from any misdirected attacks. He was also concerned about how the Soviet Union might interpret America’s military actions. Sullivan enjoyed a close personal relationship with the Soviet Ambassador to Laos, Boris Kornissovsky.24

The Salem House operations were also subject to constraints due to the Department of State and Cambodia’s Prince Sihanouk’s desire to avoid incidents that might risk Cambodian lives. Although Sihanouk had severed diplomatic relations with the United States in 1965, informal contacts with the Cambodian leader continued. In 1968, Sihanouk told U.S. Presidential Emissary Chester Bowles: “...We are not opposed to hot pursuit in uninhabited areas. I want you to force the Viet Cong to leave Cambodia....”25 Even with Sihanouk’s tacit approval for hot pursuit, combat operations in Cambodia were also governed by a concern that public exposure of these activities would bring international protest and strengthen the anti-war movement in the United States.


A final judgment of the SOG’s activities would suggest that OPS-35’s cross-border operations were an unqualified success. This success was in part due to the fact that most of the U.S. and Asian troops were already combat veterans when they joined the SOG. A second factor was the peculiar nature of the OPS-35 missions. Although the missions were hazardous, they were of short duration (usually five days) and each team conducted only one mission per month. This system afforded the team greater recovery time and training opportunities to develop higher skill levels for its members. Another comment regarding these types of operations is that despite technological advances in surveillance equipment there is no substitute for the “man on the ground,” for intelligence requires judgment as well as observation.

Historically, the SOG’s activities were especially interesting because they were politically sensitive and clearly went beyond the scope of traditional U.S. Army missions. Moreover, SOG’s operations present the student of military history with a rare example of the successful employment and management of mercenary and regular forces in the role of strategic intelligence collection. SOG’s activities were of some importance to the Free World forces that fought in the Second Indochina War.


1. Hearing Before the Committee on Armed Services, U.S. Senate, Ninety-Third Congress, First Session July 16, 23, 25, 26, 30 and August 7, 8, 9, 1973 (Washington: U.S. Government Printing Office, 1973), pages 231-255. U.S. Congressional Record, Senate (Washington: U.S. Government Printing Office, 10 September 1973), pages 29046-29052. Stanton, Shelby I., Vietnam, Order of Battle (Washington: U.S. News Books, 1981), pages 239-253. Also see the following: Schemmer, Benjamin F., The Raid (New York: Harper & Row, Publishers, 1976), pages 39-47, 71, and 117-118.

2. Stanton, page 243.

3. Simpson, Charles N., Inside the Green Berets (Navato, California: Presidio Press, 1983), page 135.

4. Stanton, Vietnam, Order of Battle, page 251. Sutton, Horace, “The Ghostly War of the Green Berets,” Saturday Review, 18 October 1969, page 25. See also Westmoreland, William C., A Soldier Reports (Garden City, New York: Doubleday & Company, Inc., 1976), page 107. Maitland, Terrence, Weiss, Stephen (Editors), The Vietnam Experience, Raising the Stakes (Boston, Massachusetts: Boston Publishing Company, 1982), pages 144-145.

5. Colby, William, Honorable Men (New York: Simon & Schuster, 1978), pages 165 and 220.

6. Hearings: Committee on Armed Services, Senate, pages 231-255. Also see Meyer, Gerald, “U.S. Forces Operate in Laos,” St. Louis Post- Dispatch, 3 November 1972, page 1.

7. U.S. Congressional Record, Senate, 10 September 1973, pages 29051-29052. BDM, The Strategic Lessons Learned in Vietnam (McLean, Virginia: BDM Corporation, 1979), Volume 6, pages 8-38.

8. Meyer, Gerald, ”Former Green Berets Verify Raids in Laos,” Saint Louis Post-Dispatch, 10 November 1972, page 1. See also Westmoreland, pages 107-108.

9. Meyer, Gerald, “Report Killings, Sabotage in Raids by U.S. in Laos,” Saint Louis Post-Dispatch, 6 November 1972, page 1.

10. Branfman, Fred, The War is Not Over (Washington: The Indochinese Resource Center, 1973), page 57.

11. The New York Times, 26 October 1970, page 1.  

12. Ibid, 12 February 1971, page 4.

13. McChristian, Joseph A., The Role of Military Intelligence (Washington: U.S. Government Printing Office, 1974), page 109.

14. U.S. Congressional Record, Senate, 10 September 1972, page 29051. For details on Salem House missions, see Hearings Before the Committee on Armed Services, U.S. Senate, Ninety-Third Congress: Bombing Cambodia; July 16, 23, 25, 26, 30 and August 7, 8, 9, 1973, pages 231-255.

15. BDM, The Strategic Lessons, Volume 6, pages 4-43 to 4-54.

16. Shawcross, William, Sideshow: Kissinger, Nixon and the Destruction of Cambodia (New York: Simon & Schuster, 1981), page 24. Hearings: Committee on Armed Services, Senate, July-August 1973, page 236. U.S. Congressional Record, Senate, 10 September 1973, page 29052. U.S. Congressional Record, Senate, 25 July 1973, page 25881.

17. U.S. Congressional Record, Senate, 10 September 1973, page 29051. Hearings: Committee on Armed Services, Senate, July-August 1973, pages 232-255.

18. Hearings: Committee on Armed Services, Senate, July-August 1973, pages 232-255.

19. The New York Times, 27 July 1973, page 3. Also see MacLean, Michael, The Ten Thousand Day War (New York: St. Martin’s Press, 1981), page 214. Tran Mai Nam was a journalist for Quan Doi Nhan Dan (People’s Army) and spent several months on the Ho Chi Minh Trail in 1967. During that time, Hanoi published his dispatches.

20. BDM, The Strategic Lessons, Volume 6, pages 6-43, 9-18, and EX-19.

21. United States Chiefs of Mission, 1778-1982 (Washington: U.S. Department of State, 1982), page 140.

22. Westmoreland, A Soldier Reports, page 196.

23. Simpson, Inside the Green Berets, page 149.

24. Arthur J. Dommen, “Laos in the Second Indochina War,” Current History, December 1970, page 327.

25. Henry Kissinger, White House Years (Boston, Massachusetts: Little, Brown & Company, 1979), pages 250-252. See also BDM, The Strategic Lessons, Volume 6, page 4-43.

Lieutenant Colonel Turkoly-Joczik (U.S. Army Retired) is now assistant professor of history at Johnson and Wales University, Charleston, South Carolina. Most recently, he served in the Middle East as a Civilian Observer for the Camp David Accords. He is a veteran of the Korean War and served as a Special Forces battalion commander in Vietnam’s Delta (IV CTZ). LTC Turkoly- Joczik holds a Doctor of Philosophy degree in International Politics from the University of Wales, United Kingdom. He is an Arab linguist and a Command and General Staff College graduate. Readers may contact him via E-mail at