Green Beret Affair

Project GAMMA
Unofficial "War Patch" of Det B57 "Project GAMMA" 5th SFGA RVN 1968–70 & US Army Special Forces SSI c. 1970
Active	1968–1970
Country	United States of America
Branch	United States Army
Type	Covert Operations
Role	Intelligence
Size	Detachment, 6 US, 460 Indigenous personnel
Engagements	Vietnam War (Cambodia)

Project GAMMA was the name given in 1968 to Detachment B-57, Company E (Special Operations), 5th Special Forces Group (Airborne), 1st Special Forces, U.S. Army in Vietnam from 1967 to 1970. It was responsible for covert intelligence collection operations in Cambodia.

Detachment B-57 arrived in Vietnam in June 1967. On 26 February 1968 it was moved from Saigon to Nha Trang and it received the designation Project GAMMA on 1 April 1968, in conjunction with other special forces units such as Project DELTA (Detachment B-52) and Project SIGMA (Detachment B-56), both responsible for Special Recon. Members of the detachment operated from nine sites under the cover of civil affairs and psychological operations offices.

Project Gamma was responsible for obtaining intelligence on Cambodian support for the activities of both regular and irregular units of the Vietnam People's Army, as well as irregular camps in Cambodia. The top intelligence officer on General Abrams' staff stated in October 1968 that Project GAMMA was providing 65 percent of the known data on NVA base camps and strengths in Cambodia, as well as 75 percent of the same data on South Vietnam. According to historian Shelby Stanton, by early 1969 Detachment B-57 "had developed into the finest and most productive intelligence-collection operation the United States had in Southeast Asia". Stanton attributes this success to the South Vietnamese authorities not being aware of operations conducted by the detachment's indigenous agents.

One source claims GAMMA was responsible for intelligence operation against Prince Norodom Sihanouk.

In early 1969 some of Detachment B-57's sources of information started to disappear. This led the detachment's leadership to conclude that its intelligence agents had been compromised. In the spring of 1969, a MACV-SOG reconnaissance team operating in Cambodia captured photos showing Chu Van Thai Khac (AKA Thai Khac Chuyen), a South Vietnamese GAMMA agent, meeting with North Vietnamese intelligence officers. Chuyen was subsequently arrested and interrogated for ten days, with polygraph tests indicating that he had compromised security arrangements and was working with the Viet Cong. Various ways of dealing with Chuyen were discussed within Detachment B-57, including possibly killing him. While the 5th Special Forces Group's executive officer strongly opposed killing Chuyen, the detachment's commander and operations officer met with the CIA headquarters in Saigon who suggested that "elimination ... might be the best course of action".