In January 1979, following the ouster of the Khmer Rouge from power by invading Vietnamese forces, hundreds of thousands of Cambodians sought food and shelter along the Thai-Cambodian border, triggering calls for international relief efforts.

Initially a consortium of international agencies known as the "Joint Mission" and consisting of UNICEF, the ICRC, UNHCR, and the WFP took responsibility for food distribution, health care, camp construction and sanitation along with considerable support from the Royal Thai Government.

[1][2] However it soon became clear that humanitarian aid provided at camps such as Sa Kaeo would permit the Khmer Rouge to recover from their near-defeat at the hands of the Vietnamese, with a protracted civil war as the likely result.

Because of this and ongoing conflicts with other aid agencies, ICRC and then UNICEF reduced their role in the management of refugee relief services on the border.

Because the operation had no staff at the beginning, UNICEF agreed to a six-month loan of its Kampuchean Emergency Unit until UNBRO could hire its own people.

While acknowledging that "physical safety is impossible to ensure and constantly at risk" in the border camps, UNBRO nevertheless outlined a broad definition of protection as a goal toward which all its activities would be oriented.

UNBRO took charge of food distribution to refugees along the border, where previously there had been widespread diversion of supplies to the Thai military and to Khmer resistance units.

[17] By the late 1980s UNBRO had standardized its basic weekly food ration so as to provide adequate daily caloric intake established by the World Health Organization.

[22] In addition, UNBRO supplied building materials to refugees and implemented an agricultural program to produce fresh vegetables in the camps.

[25] As of January 1982, UNBRO provided services to 290,000 beneficiaries in three groups: • 155,000 Cambodians in nine camps in the border's Central sector stretching from Ban Sangae to Tap Prik.

UNBRO also distributed food in two of the Khmer Rouge camps to the south of Aranyaprathet (Nong Prue and Tap Prik) although initially it was not permitted to carry out headcounts.

The Central sector also included NW82, a subcamp located at Nong Samet housing 800 Vietnamese land refugees assisted by ICRC.

In early 1983, Director Winston Prattley described the situation for donors in New York: Critics concluded that UNBRO served a purpose beyond humanitarianism—namely as a vehicle to deliver support to anti-Vietnamese factions operating out of the refugee camps located in UNBRO's area of operations, thereby complicating Vietnam's efforts to play a decisive role in Cambodia's internal politics.