There had been military observers in South Vietnam since the early 1950's following the flood of American funds and equipment to the French expeditionary army during its war in Indochina. When France left for good in 1955, the United States took over to help South Vietnam prepare itself from a possible invasion by North Vietnam.

The first advisors to South Vietnam were sent there by the Eisenhower administration and the task was to re-organize, re-equip and modernize the South Vietnamese Armed Forces after their American counterpart. Since the task was to prepare them for an invasion from the north, the focus was entirely on conventional strategies and conventional tactics - something that would backfire on them when the insurgency flared up in the late 1950's.

The role of an advisor in South Vietnam is very easy to define: they were there to help the ARVN (Army of the Republic of Vietnam) to be self-efficient and shape them into a modern army of the 20th century. After the insurgency flared up and the ARVN was put into action, many advisors accompanied units in the field to show and instruct officers and soldiers in how to face the realities of combat and how to act under it (not to mention all the other realities of soldiering).

The CIA and US Special Forces began to build up the CIDG (Civilian Irregular Defense Group) at the same time and provided the means for select villages to protect themselves from the growing insurgency. While this worked very well the short duration it lasted, the CIDG was then turned into a more offensive program, which completely defeated the purpose of its existence, since the US Army commanders saw little use in a program that wasn't offensive. They saw the purpose of the Green Berets as being gimmicky with its unconventional means as opposed to the more conventional doctrine of the US Army.