Instead, they received operational orders from the CIA Station Chief in Saigon and through the agency's satellite office in Nha Trang.

It was responsible for obtaining intelligence targeting the North Vietnamese activities and camps in Cambodia supporting both regular and irregular units of the People's Army of Vietnam (PAVN).

[3] Colonel Robert B. Rheault commanded a combined force of Green Berets and South Vietnamese commandos who entered “neutral” Cambodia to gather intelligence and destroy Communist infiltration, transportation, and storage sites.

[4] When Project GAMMA identified a target that was too big for them to hit, B-52 bombers struck those sites in technical violation of the guarantee of security the US gave to those neighboring countries.

[3] Historian Shelby Stanton wrote that by early 1969 Detachment B-57 "had developed into the finest and most productive intelligence-collection operation the United States had in Southeast Asia".

The detachment's leadership concluded that its intelligence staff had been compromised by a mole.196 Rheault had been in command of the 5th Group for only a few weeks when the suspected spy was uncovered.

A cover story claiming that Chuyen had failed to return on a mission that was a test of his loyalty was later approved by the 5th Special Forces Group's commanded by Rheault.

He quickly ordered all of the officers and men involved including Colonel Rheault arrested and confined to Long Binh Jail.

[10] The CIA issued a statement denying they knew of Chuyen when the soldiers asked them for input and that they strongly urged the Green Berets not to kill him.

[13] An official Army history of the Green Berets, published after the Vietnam War,[14] does not mention Project GAMMA or Detachment B-57.

Although the Pentagon has declassified much of the material about Green Beret operations inside Laos and Cambodia, as of 2007[update], nothing on Project GAMMA has been made available.