Having controlled the insurgencies within Thailand, in the early 1980s the government turned to protecting the country from outside aggression. Although Vietnamese forces in Cambodia were viewed as the primary external threat, border tensions, caused partly by ill-defined boundaries, between Thailand and Laos and between Thailand and Burma also created concern (see Boundaries , ch. 2). For the most part, diplomacy enabled the government to resist external pressures and to keep the use of armed force to a minimum, but the Vietnamese invasion and occupation of Cambodia in December 1978 caused severe tension along the Thai-Cambodian border. The Vietnamese stationed 140,000 troops along that frontier, along with 30,000 Cambodian troops, whom they trained, organized, and directed. The immediate presence of heavily armed and capable Vietnamese divisions on its border reinforced Thailand’s decision to improve its relations with China. In January 1979, Prime Minister Kriangsak Chomanand of Thailand and senior Chinese policy makers met secretly at Thailand’s Utapao Air Base to forge a Thai-Chinese cooperation policy. That meeting resulted in China’s halting moral and materiel support for the CPT and establishing Thailand as a conduit for Chinese support to the thailand/th_glos.asp#Khmer"> Khmer Rouge (see Glossary) faction of the Khmer resistance movement.
Thailand deployed elements of several divisions along the Cambodian border to deal with all aspects of the Vietnamese threat. There had been a history of strife along this border resulting from ethnic prejudices, poor demarcation of the boundary, and profitable cross-border smuggling, but the Vietnamese invasion of Cambodia seriously aggravated the situation. Vietnamese efforts to eliminate Cambodian resistance forces drove thousands of refugees into areas along the Thai border (see The Indochinese Refugee Question , ch. 2). Admitting large numbers of the refugees into Thailand posed severe problems for Thai authorities, not only because providing for the refugees strained the local economy but also because Khmer troops and some Vietnamese soldiers disguised as civilian refugees infiltrated Thailand. Thai security forces attempted to disarm all military infiltrators and return them to Cambodia.
Thailand supported Khmer resistance efforts as soon as the magnitude of the Vietnamese invasion became apparent in 1979. This resistance consisted of three major factions, the largest and most effective of which were remnants of the ousted communist Khmer Rouge. The noncommunist resistance groups--the forces loyal to Prince Norodom Sihanouk and the Khmer Peoples National Liberation Front (KPNLF)--also maintained their own armed combatants separate from the Khmer Rouge. All three groups, loosely aligned in the Coalition Government of Democratic Kampuchea, had their headquarters and primary bases just inside Thai territory. This situation allowed Thailand to exercise considerable control over the forces and their operations inside Cambodia, but it also provided targets for Vietnamese attack. Thailand viewed assistance to the resistance movements as essential to Thai security and, along with fellow Association of Southeast Asian Nations (ASEAN) members, waged a highly visible campaign for international assistance to Cambodian refugees and resistance forces (see Foreign Affairs , ch. 4). Assistance from China, ASEAN, the United States, and others was essential for continued viability of the Khmer resistance movement.
Vietnamese operations against the resistance along the Thai border provoked numerous clashes with Thai security forces, resulting in some casualties among Thai civilians living near the border, as well as among Thai forces. Vietnamese troops concentrated on trying to eliminate the Khmer resistance forces and to close resistance infiltration routes. They also conducted artillery attacks and made limited incursions, occupying small portions of Thai territory, notably in the border area where Thailand, Laos, and Cambodia meet.
The pattern of conflict along the Thai-Cambodian border showed little change between 1979 and 1984. Vietnamese forces conducted offensives against the Cambodian resistance forces during the dry season each year and then withdrew to consolidated positions and internal security operations well within the interior of Cambodia during the rainy season. This pattern changed with the major dry season campaign in 1984-85. In its largest and most successful series of operations, Vietnamese forces eliminated most major resistance bases along the Thai border and inflicted casualties on both refugees and armed resistance fighters. Following that offensive, Vietnamese forces remained deployed along the border during the rainy season and attempted to seal the border against the resistance forces. These efforts did not seriously hamper resistance infiltration, although they made movement into the interior of Cambodia more difficult. In the late 1980s, sizable Vietnamese forces with the limited support of units from the Khmer People’s Revolutionary Armed Forces continued to be deployed along the border.
Vietnam repeatedly assured Thailand and other ASEAN countries that it had no intention of invading Thailand, and contacts among these parties continued sporadically for several years as they explored the possibility of a political solution to the Cambodian conflict. Vietnam stated that it intended to withdraw the bulk of its forces by 1990, when it would have armed and trained the KPRAF into a credible national army. However, in mid-1987 observers doubted that the Vietnamese-supported Cambodian government would be able to assume the burden of its own defense by 1990. Even if Vietnam met its self-imposed 1990 deadline, observers expected that, as in Laos, a number of Vietnamese troops would remain in Cambodia to "advise" the KPRAF and secure Vietnamese interests in the country.
In mid-1987 the 800-kilometer Thai-Cambodian border was fully garrisoned by Vietnamese and Cambodian forces. An estimated three Vietnamese divisions and two Cambodian regiments were deployed along the northern Cambodian border adjacent to Ubon Ratchathani, Surin, Buriram, and Sisaket provinces. In the tightly contested region between Poipet in Cambodia and Aranyaprathet in Thailand’s Prachin Buri Province, there were parts of two Vietnamese divisions and three Cambodian regiments. In the former Khmer Rouge stronghold of the Phnom Milai Mountains south of Poipet, two Vietnamese divisions and one Cambodian regiment were deployed. From this region southward to the Gulf of Thailand, there were two Vietnamese divisions and three independent Vietnamese regiments. (A Vietnamese infantry division usually consists of about 10,500 officers and men; an independent regiment has a strength of about 3,000.)
Although the situation along the Cambodian border posed the greatest external threat to Thai security, other areas presented problems as well (see unavail.asp"> fig. 14). Thailand faced security challenges of varying intensity in each sector of its 2,800- kilometer border with Burma, Laos, and Malaysia. Sporadic clashes with Laos received publicity but did not pose major security threats. Armed clashes in the mountains of Nan and Uttaradit provinces were more serious but were contained by Thai security forces. This mountainous area suffered from a poorly demarcated border and was host to migrations of nomadic hill tribes and pockets of CPT resistance.
Thai security concerns along the lengthy border with Burma were complex and vexing. The numerous Burmese separatist movements posed a touchy diplomatic problem for Thailand. Annual Burmese government military operations against Mon, Karen, and Kayah separatist groups resulted in wholesale border crossings by fleeing insurgents and refugees. Thailand, however, was able to disarm and control these annual migrations. More serious were the activities of narcotics traffickers and the private armies that provided security for the narcotics trade. These elements operated along the northwestern Thai border and until the early 1980s encountered only weak response from Thai security forces. Thereafter, pressure from the United States, world opinion in general, and a new spirit of cooperation between the Thai and Burmese governments on the narcotics issue began to change the situation (see Criminal Activity and the Narcotics Trade , this ch.).
Faced with various threats along its borders, the Thai government attempted to apply the principles of its highly successful counterinsurgency program to the country’s external security problems. Encouraged by the success that road building had had in destroying the Khao Khor insurgent base, Thailand developed an extensive network of new roads along the Laotian border in Nan and Uttaradit provinces and along much of the length of the Burmese border. These roads provided easier access for security forces to remote border regions and served as a base for developing the local political, social, and economic infrastructure. Volunteer local security organizations established throughout the country in the 1980s played an important role both in containing insurgency and in enhancing security in border regions. Village security units were organized and trained by the army. Civilian agencies taught development techniques, safety measures, and village administration and provided improved health, agricultural, and educational facilities. The Rangers were locally recruited contract paramilitary forces trained in counterinsurgency and border security operations. They often joined with the army and the Border Patrol Police (BPP) to form units of forty to fifty called Santi Nimitr (Dream of Peace) teams, which carried out community development projects in remote villages where CPT front activities were reported or external threats detected. In 1987 there were more than 200 such teams operating throughout the country.
During the mid-1980s, the government continued to consolidate its political and military gains against insurgencies while turning its attention to the external threat. The government directed major efforts toward securing its borders, improving access to remote mountain regions, and strengthening domestic perceptions of the Vietnamese threat. The combination of army and BPP operations, road building and associated economic development, and resettlement resulted in a closer integration of formerly isolated areas with the rest of the country.