Military Assistance Command, Vietnam – Studies and Observations Group (MACV-SOG) was a highly classified, multi-service United States special operations unit which conducted covert unconventional warfare operations prior to and during the Vietnam War. Established on 24 January 1964, it conducted strategic reconnaissance missions in the Republic of Vietnam (South Vietnam), the Democratic Republic of Vietnam (North Vietnam), Laos, and Cambodia; took enemy prisoners, rescued downed pilots, conducted rescue operations to retrieve prisoners of war throughout Southeast Asia, and conducted clandestine agent team activities and psychological operations. The unit participated in most of the significant campaigns of the Vietnam War, including the Gulf of Tonkin incident which precipitated increased American involvement, Operation Steel Tiger, Operation Tiger Hound, the Tet Offensive, Operation Commando Hunt, the Cambodian Campaign, Operation Lam Son 719, and the Easter Offensive. The unit was downsized and renamed Strategic Technical Directorate Assistance Team 158 on 1 May 1972, to support the transfer of its work to the Strategic Technical Directorate of the Army of the Republic of Vietnampart of the Vietnamization effort. Foundation The Studies and Observations Group (also known as SOG, MACSOG, and MACV-SOG) was a top secret, joint unconventional warfare task force created on 24 January 1964 by the Joint Chiefs of Staff as a subsidiary command of the Military Assistance Command, Vietnam (MACV). It eventually consisted primarily of personnel from the United States Army Special Forces, the United States Navy SEALs, the United States Air Force (USAF), the Central Intelligence Agency (CIA), and elements of the United States Marine Corps Force Reconnaissance units. The Studies and Observation Group, as the unit was initially titled, was in fact controlled by the Special Assistant for Counterinsurgency and Special Activities (SACSA) and his staff at the Pentagon. This arrangement was necessary since SOG needed some listing in the MACV table of organization and the fact that MACV's commander, General William Westmoreland, had no authority to conduct operations outside territorial South Vietnam. This command arrangement through SACSA also allowed tight control (up to the presidential level) of the scope and scale of the organization's operations. Its mission was: ...to execute an intensified program of harassment, diversion, political pressure, the capture of prisoners, physical destruction, acquisition of intelligence, generation of propaganda, and diversion of resources, against the Democratic Republic of Vietnam. These operations (OPLAN 34-Alpha) were conducted in an effort to convince North Vietnam to cease its sponsorship of the Viet