The Studies and Observation Group was established 24 January 1964 as a joint service subsidiary branch of the Military Advisory Command Vietnam. Despite the rather unassuming name the M.A.C.V.-S.O.G. was actually a high command unconventional warfare task force with intelligence gathering responsibilities throughout South-East Asia, including Burma, Cambodia, Laos, North and South Vietnam, and the provinces of Yunnan, Kwangtung and Hainan islands of China.
Working in conjunction with the C.I.A. the Studies and Observation Group would commence covert cross-border reconnaissance and intelligence missions from US Special Forces bases in Vietnam into neighbouring Laos from September 1965 under the code name of Project SHINING BRASS,1 and following the severing of diplomatic relations in May 1965 into Cambodia from May 1967 under the code name Project DANIEL BOONE2
As US involvement in Vietnam intensified the US and ARVN Special Forces employed would increasing be despatched on reconnaissance missions into neighbouring Laos to carry out tasks aimed at interrupting North Vietnam supplies and manpower reaching South Vietnam along the ‘Ho Chi Minh’ trail. Such operations could be Linear, Area, Point and Route Reconnaissance, Route Mining, Road, trail and river watch, Interdiction and ambush, Capture of prisoners, Bomb damage assessment, Ground photography, Wiretap, Directing artillery and airstrikes against targets of opportunity, Limited direct ground assault as a part of the mission, Crash site inspection and recovery of allied/friendly prisoners held by the enemy. A typical SOG mission would commonly comprise a Spike team of three Americans and about nine indigenous Special Forces commandos.
Missions into Cambodia were restricted to a depth of 20 km (later increased to 30 km) and were divided into two zones Zone Alpha stretched from the town of Snuol north to the Laos border, and Zone Bravo from Snuol south to the Gulf of Thailand (this latter requiring presidential approval for the mission). Air interdiction missions (FREEDOM DEAL) were also permitted beyond Zone Alpha as far as Kompong Thom city. Personnel for these highly dangerous missions into Laos and Cambodia were supplied by the 5th Special Forces Group utilising US army Special Forces, ARVN Luc Luong Dac Biet (LLBE), Navy SEALs, Marine Recon, and the Air force special operations pilots of the 90th Special Operations Wing, and at its peak the MACV-SOG had some 2,000 Americans and over 8,000 indigenous personnel assigned. Many members of 1st S.F. Group on Okinawa served in SOG along with substantial numbers from 7th SF Group. There was never a lack of volunteers.
The number of MACV-SOG missions conducted with Special Forces reconnaissance teams into Laos and Cambodia numbered 117 in 1966, 258 in 1967, 327 in 1968 and 452 in 1969 earning the Special Forces no less than five Medals of Honour, two of which were posthumous awards. After April 1971 US Special Forces were prohibited from crossing into Laos by the US Congressional Cooper-Church amendment although ARVN Special Forces continued to do so until the end of the second Indochina war (1975).