In the aftermath of the Tet Offensive a joint session of the South Vietnamese legislature agreed on a military mobilization law which was promulgated on 19 June 1968.

In addition, the legislation specified that youths of 17 and men between the ages of 39 and 43 could be conscripted for noncombat military service, and all other males between 16 and 50 were to serve in a new paramilitary organization, the People's Self-Defense Force, a part-time hamlet militia.

They were also organized into teams, sections, and groups but separated into different categories: elders, women, and teenagers, as dictated by traditional Vietnamese culture.

[2]: 68 In relatively secure areas, the PSDF could be employed to assist the National Police in maintaining law and order, defending against PAVN/VC sabotage and terrorist actions, and interdicting PAVN/VC penetrations.

They mounted guard, conducted patrols and supported the police or military forces by gathering intelligence, providing first-aid, assisting in medical evacuation, constructing defense barriers, installing simple booby traps, and acting as messengers.

Their capabilities were usually limited to warning the hamlet people and the nearest friendly force, and taking up concealed positions along the path of the PAVN/VC's approach, harassing and sniping at them.

In many cases of PAVN/VC penetrations, the hardy and more experienced PSDF members even violated the rule by joining the PF to fight back as a reaction force.

The training was performed in the hamlet for a few hours during the day and so arranged to avoid disrupting normal activities of PSDF members.