Military history of Cambodia

History attests to Cambodia's martial origins. In antiquity Cambodia, having conquered Laos, parts of Thailand, and the Malay Peninsula, held power over a vast area of Southeast Asia.

Khmer martial prowess waned in the early 15th century, however, and Cambodia subsequently endured periods of colonisation, occupation, and vassalage by its more militarily powerful neighbours, Thailand and Vietnam. This long period of decline reached its nadir in the early 19th century, when Cambodia nearly ceased to exist as a sovereign state as the result of encroachments by its neighbours. In 1863 the Cambodian king acquiesced in the establishment of a French protectorate over his nation, to preserve it from extinction. The protectorate's authority was extended often by force of arms, and ultimately Cambodia became a de facto colony that eventually gave birth to a modern state with its own armed forces and military doctrine.

Since World War II, Cambodia has enjoyed few strife-free periods. Its people have suffered colonisation, prolonged civil war, and occupation by a foreign power almost continuously. During this time, it has been ruled by three authoritarian governments of differing ideological orientations and varying degrees of repression.

American military aid to Cambodia began indirectly in 1950 in the form of a security assistance program for the French forces in Indochina, that enabled them to expand a recently created indigenous army. In 1955 the United States agreed to continue this aid to the independent kingdom of Cambodia. The program, which included military training and a resident Military Assistance Advisory Group (MAAG), lasted until terminated by the Cambodian government. Security assistance was again extended to the Khmer Republic from 1970 until that government fell in 1975 to the Khmer Rouge. After 1975 the United States extended humanitarian assistance through United Nations (UN) agencies to Cambodian refugees on the Thai border and gave non lethal aid, only, to the two non communist components of the Coalition Government of Democratic Kampuchea.

In 1987 Cambodia was the reluctant host to a substantial Vietnamese military presence, reinforced by its Cambodian surrogate army. History thus appeared to be repeating itself, and foreign observers and Cambodian nationalists feared that the country eventually might become part of a Hanoi-dominated Indochinese federation. The UN recognised the tripartite CGDK as the legitimate government of Cambodia. The insurgent forces of the coalition were capable only of conducting guerrilla raids and sabotage missions within Cambodian territory, against the Vietnamese occupation forces and the Kampuchean (or Khmer) People's Revolutionary Armed Forces of the Phnom Penh government, the People's Republic of Kampuchea. A number of foreign observers assessed the military situation as a stalemate and doubted that Hanoi would, or could, fulfil its public commitment to withdraw its forces by 1990 from a Cambodia that was becoming a "strategic appendage" of the "indivisible strategic unit of Indochina" claimed by Vietnamese military doctrine.

Khmer Empire

Khmer army going to war against the Chams

Bas-relief in galleries of the Angkor complex in Siem Reap depict Cambodia's land and naval conquests during the Angkorian Period, which spanned from A.D. 802 to 1431. During this time, the Khmer Empire, by force of arms, extended its dominions to encompass much of Southeast Asia. The warrior kings, who actually led troops in battle, did not customarily maintain standing armies but raised troops as necessity required. Historian David P. Chandler has described the relationship between the monarch and the military:

Though the king, who led his country into battle, sometimes engaged his chief enemy in single combat, Khmer military strength rested on the junior officers, the captains of militia. These men commanded the loyalty of peasant groups in their particular locality. If the king conquered a region, a new captain of militia would be enrolled and put under an oath of allegiance. The captains were simply headmen of the outlying regions, but their connection with the king enhanced their status. In time of war they were expected to conscript the peasants in their district and to lead them to Angkor to join the Khmer army. If the captains disobeyed the king they were put to death. The vast majority of the Khmer population were of the farmer-builder-soldier class.

Little is known conclusively about warfare in early Cambodia, but much can be assumed from the environment or deduced from epigraphic and sculptural evidence. The army was made up of peasant levies, and because the society relied on rice cultivation, Khmer military campaigns were probably confined to the dry season when peasant-soldiers could be spared from the rice fields. Battles were fought on hard-baked plains from which the paddy (or rice) had been harvested. Tactics were uncomplicated. The Khmer engaged their foes in pitched frontal assaults, while trying to keep the sun at their backs. War elephants were widely employed, for both tactical and logistical purposes. Late in the Khmer Empire, the ballista (a kind of catapult, often shaped like a giant crossbow) took its place in regional warfare. It probably was introduced to the Cambodians by Cham mercenaries, who had copied it earlier from Chinese models.

Ballista war elephants attacking the Chams

The Khmer Empire's principal adversaries were the Siamese, the Vietnamese, and the Cham from the powerful kingdom of Champa in central Vietnam. Warfare, seemingly, was endemic, and military campaigns occurred continuously. The Chams—attacked by land in 1177 and again by water in 1178—sacked Angkor twice. In 1181 a young nobleman who was shortly to become Jayavarman VII, emerged as one of the greatest of the Khmer kings, raised an army and defeated the Chams in a naval battle. After his death, ca. 1218, Kampuja entered a decline, resulting in eventual disintegration.

Dark ages

Scholars frequently assert that the decline of the Khmer Empire was precipitated by the drain on its economy, and on the morale and energy of its people, caused by the continual and monumental construction program at Angkor. Dynastic rivalries took their toll, and slave rebellions are also thought to have hastened the demise of the empire.

Ayutthaya invaded Cambodia in the Siamese–Cambodian War (1591–94).

The Cambodians defeated the Spanish in the Cambodian–Spanish War.

The Cambodians defeated the Dutch East India Company in a war from 1643-44 on the Mekong River.

Over the centuries, the Khmer kings never completely pacified the countryside. Khmer martial spirit survived, as was demonstrated by uprisings and rebellions, either spontaneous or contrived, throughout periods of foreign encroachment and domination. Among the significant rebellions was one that occurred beginning in 1840 which resulted in Cambodia's being placed under the joint suzerainty of Thailand and Vietnam.

Colonial Cambodia

Following entreaties that had been made a decade earlier by Cambodian King Ang Duong to Napoleon III for protection from the Vietnamese, his "traditional enemies", a delegation of French naval officers in 1863 proceeded to Phnom Penh from Saigon to conclude a treaty with Duong's son, now King Norodom (1859–1904), that created a French protectorate. It is generally accepted by historians that only the intervention of the French prevented the extinction of Cambodia.

Heavy taxation as well as resentment against foreign domination and the puppet rulers who sat on the throne in Phnom Penh were the causes of the intermittent rebellions that marked the colonial period. Revolts erupted in 1866 and in 1870 that attracted considerable support in the countryside. They were quelled by the French, assisted by Norodom's half brother (the future king), Sisowath, who led his troops alongside the French in the suppression of both rebellions.

Another serious rebellion occurred in 1884, when the French forced upon King Norodom a new treaty that tightened their control over Cambodia. The reforms stipulated in the new accord, such as the abolition of slavery and the nstitutionalisation of land ownership, struck at the very heart of the privileged status enjoyed by the Cambodian elite in the countryside. The result was a widespread insurrection evoking such support that a local French official in Kampong Cham noted in 1886 that "...the entire Cambodian population acquiesces in the revolt." Quelling the rebellion took one and one-half years, and it tied down some 4,000 French and Vietnamese troops that had been brought in from Cochinchina (the southern part of Vietnam).

Unrest surfaced periodically before World War II, and various episodes of Cambodians' defying colonial rule were recorded. Reports by French officials also hinted at widespread insecurity in the countryside, where peasants frequently were at the mercy of bandit gangs. The colonial military forces in Cambodia, which were available to quell potential insurrections during this period, consisted of a light infantry battalion (Bataillon tirailleurs cambodgiens) and a national or native constabulary (Garde nationale, also called Garde indigène).

The light infantry battalion, a Khmer unit with French officers, was part of a larger force, the third brigade, which had responsibility for Cambodia and for Cochinchina. In addition to the Cambodian battalion, the brigade was composed of French colonial and Vietnamese light infantry regiments and support elements. The brigade, headquartered in Saigon, was ultimately responsible to a supreme military command for Indochina located in Hanoi.

Under the French pre-World War II colonial regime, the constabulary consisted of a force of about 2,500 men and a mixed Franco–Khmer headquarters element of about forty to fifty officers, technicians, and support personnel. The force was divided into about fifteen companies deployed in the provinces. Control of the constabulary was vested in the colonial civil administration, but in times of crisis, command could pass quickly to military authorities in Saigon or in Hanoi. Service in the constabulary theoretically was voluntary, and personnel received a cash salary. Enlistments, however, were rarely sufficient to keep pace with personnel requirements, and villages occasionally were tasked to provide recruits.

Japanese occupation (1941-1945)

In 1940 the Japanese government, after negotiating a treaty of friendship with Thailand, sought special concessions in Indochina from the French colonial authorities. The Vichy administration in Hanoi, under pressure from the German government, signed an agreement with Tokyo that permitted the movement of Japanese troops through the transportation hubs of Indochina.

Thailand subsequently sought to take advantage of both its friendship with Tokyo and French military weakness in the region by launching an invasion of Cambodia's western provinces. Although the French suffered a series of land defeats in the skirmishes that followed, a unique twist in the confrontation came from a naval battle that ensued near the Thai island of Ko Chang. A small French naval force intercepted a Thai battle fleet, en route to attack Saigon, and sank two battleships and other light craft. The Japanese then intervened and arranged a treaty, signed in Tokyo in March 1941, compelling the French to concede to Thailand the provinces of Batdambang, Siemreab, and parts of Kampong Thum and Stoeng Treng. Cambodia thus lost one-third of its territory and nearly half a million citizens.

The Japanese, while leaving the Vichy colonial government nominally in charge throughout Indochina, established in Cambodia a garrison that numbered 8,000 troops by August 1941. Preservation of order on a day-to-day basis, however, continued to be the responsibility of the colonial authorities, who were permitted to retain the constabulary and the light infantry battalion. These forces were sufficient to quell the first stirrings of nationalistic unrest in 1941 and in 1942.

Anti-French agitation assumed a more overt form, in July 1942, when early nationalist leaders Pach Chhoeun and Son Ngoc Thanh organised a demonstration in Phnom Penh over an obscure incident involving Cambodian military personnel. In this occurrence, a monk named Hem Chieu attempted to subvert some Khmer military personnel by involving them in vague coup plotting against the colonial administration. The plot was discovered, and the monk was arrested; Chhoeun and Thanh, believing they had tacit Japanese support, staged a march on the French residency by some 2,000 people, many of them monks. The repressive reaction by the colonial authorities resulted in many injuries and in mass arrests. Although the Japanese failed to support Thanh as he had expected, they spirited him away to Japan, where he was trained for the next three years and was commissioned a captain in the Japanese army. Chhoeun was arrested and sentenced to life imprisonment.

Flag of the short-lived Cambodian pro-Japanese puppet state (March–October 1945)

On 9 March 1945, Japanese forces in Indochina, including those in Cambodia, overthrew the French colonial administration; and, in a bid to revive the flagging support of local populations for Tokyo's war effort, they encouraged indigenous rulers to proclaim independence. During this period of Japanese-sponsored independence, the fate of the constabulary and of the light infantry battalion remained uncertain. The battalion apparently was demobilised for the most part, while the constabulary remained in place but was reduced to ineffectuality. Presumably both forces were leaderless because their French officers were interned by the Japanese for the remainder of the war.

Tokyo, however, did not plan to leave the Indochinese countries without a military force following the 9 March coup. Plans had been prepared for the creation of 5 volunteer units of 1,000 troops each. There was no thought that such a native force would fight alongside Japanese troops, but rather that it would be used to preserve public order and internal security. It was intended that recruitment of indigenous personnel for the volunteer units would be through physical and written exams. Before the plan could be implemented in Cambodia, however, the war ended, and the concept died without further action.

The conclusion of World War II caused considerable turmoil in Cambodia: a defeated Japanese military contingent waited to be disarmed and repatriated; French nationals newly released from internment sought to resume their prewar existence; diverse Allied military units returned to Phnom Penh to reimpose a colonial administration. In the countryside there were two sources of unrest. On the western fringes of the country, the Khmer Issarak, nationalist insurgents with Thai backing, declared their opposition to a French return to power in Cambodia, proclaimed a government-in-exile, and established a base in Batdambang Province. On the eastern frontier, the Vietnamese communist forces, or Viet Minh infiltrated the Cambodian border provinces, organised a "Khmer People's Liberation Army" (not to be confused with the later Cambodian force, the Kampuchean People's National Liberation Armed Forces, which is sometimes called the Khmer People's National Liberation Army), and began seeking a united front with the Khmer Issarak.

First Indochina War (1945-54)

It was under such exigencies that a Cambodian army was created, primarily by Prince Monireth, the heir to the throne, who earlier had been passed over by the French in favour of Prince Norodom Sihanouk, who was considered more pliable. In the fall of 1945, Monireth gained the concurrence of returning French authorities in his plan to raise an indigenous military force to fill the vacuum left by the defeated Japanese and to counter mounting internal disorder. On 23 November, in his capacity as defence minister, he made public two decisions concerning this issue. The first was to form the first battalion of a nascent Cambodian army, and he invited former noncommissioned officers (NCOs) of the demobilised colonial light infantry battalion to join the new unit. The second was to open an officer-candidate school, and he extended an invitation to young men between the ages of eighteen and twenty five with a junior high-school education to apply for admission. The school duly opened on 1 January 1946, and part of it was reserved for NCO training.

Two important agreements between Phnom Penh and Paris gave the Cambodian military forces a firmer official footing in 1946. The first, the Franco–Cambodian Modus Vivendi of 7 January 1946, for the most part concerned political matters. In military affairs, however, it gave official recognition to the existence of a Cambodian army, although it placed French advisers in the Cambodian Ministry of Defense and declared that French authorities had responsibility for maintaining order in Cambodia.

The second agreement, the Franco–Cambodian Military Convention of 20 November 1946, was more significant in Cambodian military history because it established the organisation and the mission of the nation's armed forces. The pact affirmed that Cambodia, as an autonomous state within the French Union, would have at its disposal indigenous forces, the missions of which were to uphold the sovereignty of the king, to preserve internal security, and to defend the frontiers of the country. The accord also noted that Cambodia participated in the defence of the French Union by placing its military units at the disposal of the French High Commissioner for Indochina, and that, reciprocally, other French Union forces helped to defend Cambodia. The Cambodian forces were to be composed of units with a territorial responsibility and a mobile reserve. The supreme commander would be the king, who would exercise his powers through a Ministry of Defense assisted by a Franco-Khmer general staff. The Cambodians also were granted the responsibilities of recruiting, of determining obligatory military service, of designating unit tables of organisation and equipment, and of deploying troops internally. The stationing of Cambodian units outside the country, however, was to be based on mutual understanding between the king and the French High Commissioner for Indochina (see The Struggle for Independence, ch. 1).

In 1947 the Cambodian government faced a mounting threat from several thousand Khmer Issarak combatants, whose numbers would swell to around 10,000 by 1949. In an effort to keep pace with their domestic adversaries, the Cambodian military forces slowly but inexorably grew in numbers as the months and years passed. In January 1947, the effective strength of the Cambodian military stood at about 4,000 personnel, of which 3,000 served in the constabulary. The remainder were in a mobile reserve of two battalion-sized units (one of them newly formed) named, respectively, the First Cambodian Rifle Battalion and the Second Cambodian Rifle Battalion (Bataillon de Chasseurs Cambodgiens). These first Cambodian military units went into action in 1947 against the Khmer Issarak. During the next two years, two more rifle battalions were added, bringing total strength up to 6,000 personnel, with about half serving in the Garde Nationale and half in the mobile reserve. The latter at this time comprised three rifle battalions (one battalion had been allocated to French Union forces elsewhere in Indochina).

In July 1949, in another military agreement with France, Cambodian forces were granted autonomy within operational sectors in the provinces of Siemreab and Kampong Thum, which had been part of the territory returned to Cambodia by Thailand in early 1947. Under an additional protocol signed in June 1950, provincial governors were assigned the responsibility for the pacification of the territories under their jurisdictions; to accomplish this mission they were each given a counterinsurgency force consisting of one independent infantry company.

The early 1950s were marked by further milestones in the development of the Cambodian military forces. In the fall of 1950, a military assistance agreement between the United States and France provided for an expansion of indigenous forces in Indochina, and by 1952 Cambodian troop strength had reached 13,000 personnel, greater than that of French forces in the country. In the meantime, more rifle battalions were formed, combat-support units were established, and a framework for logistical support was set up. Cambodian units were given wider responsibility: protection of the rubber plantations in the area of the middle Mekong, and, to prevent infiltration by the Viet Minh, surveillance of the coastal areas of the southern provinces and of the eastern frontier with Cochinchina.

In June 1952, Prince Sihanouk – determined to transcend his figurehead role – seized power, staging what was termed a "royal coup d'état." He suspended the constitution "to restore...order and security throughout the country." Taking command of army operations, he led his troops against Son Ngoc Thanh's Khmer Issarak forces in Siemreab Province, where he announced that he had driven "700 red guerrillas" across the border into Thailand. As the year wore on, the French returned to Cambodian control the battalion that had been assigned to the French Union forces since the late 1940s. The unit returned ceremoniously to Phnom Penh in October. In December the Cambodian operational sector of Siemreab was enlarged by the addition of Batdambang Province, and the subsector of Batdambang City came under the command of a previously obscure lieutenant colonel, Lon Nol. The operational sector of Kampong Thum was given its own combat element, the Third Cambodian Rifle Battalion, an elite unit that was subject to the direct orders of the monarch.

In early 1953, Sihanouk embarked on a world tour to publicise his campaign for independence, contending that he could "checkmate communism by opposing it with the force of nationalism." Following his tour, he "retired" to Batdambang Province, which was declared a "free zone of independence" and where he was joined by 30,000 Cambodian troops and police in a show of support and strength. Elsewhere, Cambodian troops under French officers staged slowdowns or refused the commands of their superiors, as a demonstration of solidarity with Sihanouk. Full independence was granted by France in November 1953, and Sihanouk, returning to Phnom Penh, took command of the army of 17,000 troops, which had been renamed the Royal Khmer Armed Forces (Forces armées royales khmères – FARK – see Appendix B).

In March 1954, combined Viet Minh and Khmer Issarak forces launched attacks from Vietnam into northeastern Cambodia. Sihanouk personally directed a sustained counterattack. Conscription was instituted for men between fifteen and thirty-five years of age, and national mobilisation was declared. Following the conclusion of the Geneva Conference on Indochina in July, Viet Minh representatives agreed to withdraw their troops from Cambodia. After a brief rebellion by the Khmer Issarak in late 1954, one of its principal leaders, Son Ngoc Thanh, surrendered in response to an amnesty decree, but, upon denial of an audience with Sihanouk, he departed for Thailand. FARK force levels were 47,000, but, with demobilisation after Geneva, this dropped to 36,000, the approximate level at which it was to be maintained for the next fifteen years except during periods of emergency.

The Second Indochina War (1954-75)

In May 1955, the United States and Cambodia signed an agreement providing for security assistance and for the establishment of a thirty-person MAAG. During the next eight years, until the assistance program was discontinued at Cambodian request in November 1963, FARK received from the United States supplies and equipment worth approximately US$83.7 million, in addition to military budget support. In the meantime, the French also retained a military training mission in Cambodia that was to remain until 1971. FARK traditions and doctrine remained French, and there was some incompatibility with United States military doctrine and outlook.

Cambodia supported the United Front for the Liberation of Oppressed Races during the FULRO insurgency against Vietnam against both South Vietnam and the Vietnamese Communists.

Although the United States undertook a substantial security assistance program in Cambodia, and the kingdom was included as a "protocol state" in the Southeast Asia Treaty Organization (SEATO), failure to obtain more concrete assurances of defence assistance motivated Cambodia to adopt a neutralist foreign policy. Subsequently adopted as law, this policy declared that Cambodia would "abstain from military or ideological alliances" but would retain the right to self-defense. Cambodia continued to be aware of the serious threat to its independence posed by the Democratic Republic of Vietnam (North Vietnam).

FARK's mission thus became a defensive one, that is, to insure Cambodia's territorial integrity within the framework of neutrality. The FARK high command remained fairly stable, staffed by a limited number of well-trained personnel, many of whom had been educated abroad. Ranking officers, however, became highly politicised, if not subservient, because they were more or less compelled by Sihanouk at his whim to perform active roles in national political life. Throughout the years that followed the Geneva Conference, Sihanouk, supreme commander of FARK, controlled national policies affecting the military establishment, and FARK's operational parameters were circumscribed by his frequent policy vacillations. Because of this, FARK never developed as an effective or viable military organisation.

In addition to the Vietnamese threat, the Cambodian government perceived a menace to internal stability from Son Ngoc Thanh's resurgent antimonarchist Khmer Serei (see Appendix B). Although contemporary observers suggested that the Khmer Serei seemed "to be more of a nuisance... than a genuine threat", the group's insurgent activities and subversive efforts were viewed with increasing alarm by Phnom Penh. In March 1959, for example, the provincial governor of Siem Reap, General Dap Chhuon, a former Khmer Issarak leader who once had fought alongside Sihanouk, was implicated in an attempted Khmer Serei uprising (known at the time as the Bangkok Plot) and was executed. Sihanouk believed the United States had been behind the plot, and his proclivity for assuming complicity between Washington and the Khmer Serei became a particularly significant factor a few years later. In approximately 1965 to 1966, the United States Military Assistance Command—Vietnam (MACV) began recruitment for the Studies and Operations Group and civilian irregular defence groups of Khmer Krom (see Appendix B) living in the Mekong Delta, many of whom were Khmer Serei members. In his public pronouncements regarding Khmer Serei activity, Sihanouk charged that the group had originated in South Vietnam and Thailand, and had the backing of both governments. Over the years, there were countless Khmer Serei incidents, followed by amnesties, surrenders, executions, and acrimonious Cambodian charges against South Vietnam, Thailand, and the United States. After Sihanouk was deposed in 1970, the Lon Nol government pardoned some 500 political prisoners, the majority of whom were Khmer Serei. Charges surfaced in 1987 that during his rule Sihanouk had executed as many as 1,000 Khmer Serei suspects.

In the uneasy peace between the First Indochina War and the Second Indochina War, a number of incidents occurred on Cambodia's border with South Vietnam. In June 1958, two South Vietnamese battalions briefly occupied a village in Stoeng Treng Province, and Sihanouk appealed for United States intervention. Receiving no response that satisfied him, Sihanouk established diplomatic relations with China and announced that this action was a direct consequence of South Vietnam's violation of Cambodian territory. Cambodia was also not silent during the early stages of border violations by North Vietnam. In 1959 Phnom Penh complained that North Vietnamese regulars were using northeastern Cambodia to infiltrate South Vietnam. Cambodia made concerted efforts to demonstrate that it was policing its eastern borders, but, although the incursions were publicly admitted, the existence of base areas was not. By the mid-1960s, sites along Cambodia's eastern borders were serving as bases for North Vietnamese and for South Vietnamese communist, or Viet Cong (see Appendix B) forces fighting the South Vietnamese government. FARK, restrained by Sihanouk's policies, which, in effect, constituted a modus vivendi with the intruders, could do little more than monitor these activities. The continuation of border incidents, and Sihanouk's repeated charges of United States complicity with the Khmer Serei, led to a steady deterioration in Cambodian–American relations.

In November 1963, after the clandestine Khmer Serei radio resumed anti-Sihanouk broadcasts that the Cambodian government alleged were beamed from Thailand and from South Vietnam with transmitters supplied by the United States, Sihanouk terminated the economic and security assistance agreements with Washington. He also demanded the departure from Cambodia of all non-diplomatic United States government personnel. The final rupture in diplomatic relations came two years later, after Cambodia filed a complaint in the UN Security Council against the United States and South Vietnam for their "repeated acts of aggression against Cambodia." Relations were formally terminated 3 May 1965.

Although still receiving French military assistance and training (a program that was to continue until 1972), Cambodia began soliciting and accepting military assistance from communist countries as well, after the termination of United States aid. In 1963 FARK received four Soviet MiG aircraft at the beginning of a program in which China also joined. The inevitable results of a variety of suppliers were mixed equipment inventories.

In 1966 Sihanouk secretly granted access to the deep-water port of Sihanoukville (later called Kompong Som), in western Kampot Province, to the North Vietnamese. With the complicity of ranking FARK officers, Sihanoukville became a main entrepôt for North Vietnamese military supplies from China and from the Soviet Union. Armaments were then transported to North Vietnamese and Viet Cong sanctuaries on the border with South Vietnam, ironically over the "Friendship Highway" built with United States aid and sometimes in FARK trucks supplied as part of the United States security- assistance program. This effective supply route enabled the North Vietnamese and the Viet Cong to stockpile substantial amounts of armaments and equipment for the 1968 Tet Offensive against the Saigon government. FARK profited from armaments pilfered from the Vietnamese shipments, and suborned FARK officers derived personal advantage from the Sihanoukville traffic through fees, bribes, and other special arrangements.

In 1967 a peasant uprising broke out in the Samlot district of Batdambang Province. Its significance was not appreciated immediately. At the time, Sihanouk attributed the attacks, which first occurred in about January, to the 'Khmer Viet Minh', whom he also labelled "Khmer Rouge" to distinguish them from the "Khmer Bleu" (see Appendix B). Sihanouk vacillated in placing the blame for the unrest, however, and later charged the "Thai patriotic front" with being its instigators. Acting on his orders, FARK harshly suppressed the Batdambang insurgents, who had acted spontaneously, and not at Khmer Rouge direction. Although Sihanouk announced two months later that the Batdambang rebellion was "completely at an end", there were subsequent references to continuing Khmer Rouge activity in the countryside.

The uprising convinced the Khmer communists (including a former school teacher named Saloth Sar, later to emerge under the alias Pol Pot) who earlier had gone underground, that the time was at hand to escalate the armed struggle against the Phnom Penh government. Shortly thereafter, the Revolutionary Army of Kampuchea (RAK – see Appendix B) came into being. The Khmer Rouge dated its own founding from 17 January 1968. RAK leaders, including Pol Pot, who had just returned from a prolonged visit to China, retreated to the jungle and mountains of Ratanakiri Province (Ratanakiri) in northeastern Cambodia. There they hoped to exploit the disaffection of the Khmer Loeu (see Appendix B) over the policies of the Phnom Penh government concerning taxation, corvée labour, and the resettlement of lowland Khmers in the Khmer Loeu areas. For the next two and one-half years, the newly formed RAK remained small (estimates varied from 400 to 2,000 personnel), and poorly equipped with captured weapons. The Khmer Rouge found that, in spite of the Samlot rebellion, discontent against the government in Phnom Penh was then insufficient to attract large numbers of people to the rigors of an armed insurgency. As for external support, there was no move on the part of Hanoi to provide military assistance to the Khmer Rouge because such action would have alienated Sihanouk's government and would have imperiled continued North Vietnamese and Viet Cong access to Cambodian territory as well as their use of the port of Sihanoukville.

In 1969 the United States undertook the first of two bombing campaigns against enemy targets in Cambodian territory. Code-named the Menu series, these air operations consisted of tactical strikes against North Vietnamese and Viet Cong base areas on the Cambodian- Vietnamese border. They partially dislodged the North Vietnamese and the Viet Cong and drove them more deeply into Cambodia in quest of safer havens. This brought FARK elements into more frequent hostile contact with the communists, and there were reports of FARK forces' being involved in joint operations with South Vietnamese forces against the North Vietnamese and the Viet Cong. Sihanouk became increasingly distressed with these developments; his attitude toward the communist Vietnamese changed, and authorisation for continued use of Sihanoukville was terminated. In April, speaking in Ratanakiri Province, Sihanouk stated that "to deal with the Viet Cong and Viet Minh", he had ordered General Lon Nol "to give up the defensive spirit and adopt an offensive spirit." Sihanouk announced during a press conference on 11 June 1969 that "...at present there is war in Rotanokiri [province] between Cambodia and Vietnam."

Sihanouk left Cambodia for medical treatment in France in January 1970. Citing disagreement over economic and administrative matters, after week-long anticommunist rioting in Phnom Penh, the Cambodian National Assembly on 18 March passed a unanimous vote of nonconfidence in Sihanouk and replaced him as chief of state (see The March 1970 Coup d'État, ch. 1). Although Sihanouk's deposition was nominally a parliamentary action, the leaders of the participants consisted primarily of FARK officers, headed by Lon Nol, who had been the prime minister since the previous August (and who, Sihanouk had once suggested, would be his likeliest successor). The coup was bloodless, although FARK contingents were on the alert in Phnom Penh and took control of key installations, such as the airport and the radio station.

At the time Sihanouk was deposed, FARK, soon to be renamed the Khmer National Armed Forces (Forces armées nationales khmères – FANK – see Appendix B), had 35,000 to 40,000 personnel, organised for the most part as ground forces. The Lon Nol government repeatedly sought negotiations for a peaceful withdrawal of the North Vietnamese and the Viet Cong forces from its territory. These overtures were rejected, and in April the Vietnamese communists began moving out of their sanctuaries and deeper into Cambodia, in efforts to preserve their lines of communication and to maintain the corridor to the port of Sihanoukville. President Richard M. Nixon spoke on 30 April 1970 to the American nation, and said that "thousands of their [North Vietnamese and Viet Cong] soldiers are invading the country from the sanctuaries and they are encircling the capital." Lon Nol, in the meantime, had called up military reserves, had requested UN intervention, and, while reiterating Cambodia's position of neutrality, had issued a call for international assistance.

Between 29 April and 1 May 1970, South Vietnamese and United States ground forces drove into Cambodia's border areas in a determined bid to overrun and to destroy North Vietnamese and Viet Cong logistical depots and sanctuaries. There also was hope at United States MACV headquarters that the offensive would result in the capture of the Central Office for South Vietnam, the Viet Cong headquarters for directing the war against the Saigon government. The operation resulted in the capture of vast quantities of enemy matériel and it bought time for Washington and Saigon to proceed with "Vietnamization", the process of turning over the conduct of the war to the South Vietnamese government. For the shaky Lon Nol government in Phnom Penh, however, the results of the incursion were destabilising and far-reaching. In retreating before United States and South Vietnamese troops, North Vietnamese and Viet Cong forces penetrated farther west into Cambodian territory, over-running government outposts as they went. Soon all of northeastern Cambodia had fallen to the North Vietnamese or to the Viet Cong, who then proceeded to turn the captured areas over to the Khmer insurgents and to forge them into a full-fledged revolutionary army.

To help hard-pressed FANK, Nixon laid down guidelines for United States assistance to Cambodia, promising, among other things, to turn over to the government in Phnom Penh equipment captured during the incursion, and to "provide military assistance...in the form of small arms and relatively unsophisticated equipment in types and quantities suitable for their army." Thus began a structured military assistance program, supplementing the ad hoc support begun shortly before the incursion, that was to total US$1.18 billion by the fall of the Lon Nol government in April 1975. Although all United States troops were withdrawn from Cambodian territory, South Vietnamese forces were accorded "automatic authority" to operate in Cambodia in a sixteen-kilometer corridor along the frontier.

The Lon Nol government very shortly afterwards declared martial law and total mobilisation, and it began expansion of its army. United States government studies conducted shortly before Sihanouk's deposition had expressed serious reservations about the capabilities of the government forces, noting the "lack of combat experience, equipment deficiencies,... lack of mobility", and citing "incompetent and corrupt officers" as the "greatest shortcoming."

The same officers were, however, retained by FANK and their inadequacy rapidly became apparent as military rosters were padded with non-existent "phantom troops." United States advisers attempting to keep track of FANK's development were constantly hampered by the difficulty of accurately estimating the number of Cambodian troops. (Accurate numbers were important because the United States was then providing assistance for FANK's military pay and allowances.) United States Senate staff investigators reported that United States officials acknowledged in January 1972 that the Khmer Republic's military strength figures were "grossly exaggerated" by at least 10 percent. The Senate report concluded there was "no greater mystery in Cambodia than the size of the Cambodian Government's armed forces." In December 1972, the information minister of the newly proclaimed Khmer Republic announced that 100,000 troops were found to be "nonexistent." According to the United States secretary of state's report to the Congress for the years 1969 and 1970, FANK grew "from under 40,000 in March 1970 to some 200,000 in January 1971." In reality, FANK levels probably never reached such a high number, and many of its new soldiers were youthful and inexperienced.

Limited basic training of the inductees, some of it in Thailand and in South Vietnam, began almost immediately after the introduction of martial law. Such training, however, could not satisfy FANK's pressing need to teach peasant farmers to man the equipment provided by the United States, to fight effectively in sizeable units, and to comprehend modern military doctrine.

In spite of a steady infusion of United States security assistance and the influx of new FANK personnel, the government forces were unable to hold their own against their adversaries. Because much of the country remained under North Vietnamese control after the withdrawal of United States and South Vietnamese troops, initial FANK strategy focused on holding the heartland of Cambodia south of a line of demarcation dubbed the "Lon Nol Line." This strategy conceded about half the country to the enemy, but it was the heavily forested, sparsely populated, northern half. If the Lon Nol Line could be held, the government would control the southern half with most of the population and all of the rich, rice-growing areas.

To defend this territory, FANK unleashed its two most ambitious offensives: Chenla I, in August 1970, and Chenla II, in August 1971. Both had as their objectives the reopening of National Highway 6 to Kompong Thom and the reassertion of government control over this fertile agricultural area. Both operations failed. Chenla I stalled short of its objective in the face of fierce resistance from the North Vietnamese Ninth Division. FANK units were then withdrawn to protect the capital from enemy commando teams. Chenla II was successful in securing its initial goals, and FANK columns from north and south met jubilantly on Route 6 along the way to Kompong Thom. As the government forces celebrated, however, their old nemesis, the North Vietnamese Ninth Division, tore into the extended FANK lines with ferocity, slaughtering many of them and leaving the rest cut off and compelled to fight their way back to their own lines as best they could. Former FANK commander General Sak Sutsakhan noted ruefully about Chenla II after the war that, "In this operation FANK lost some of its best units of infantry as well as a good part of its armor and a great deal of transport, both military and civil."

The North Vietnamese, however, were neither the only, nor the most determined adversary with whom FANK had to deal. A far more lethal threat was soon posed by a revitalised Khmer Rouge-dominated force that had evolved considerably since its days as the ragtag, poorly armed band of irregulars known then as the RAK. The development of the RAK had owed much to the opportunism of the Khmer Rouge leaders, who had been able to transform a forlorn communist insurgency with no chance of succeeding in the late 1960s, into a war of national liberation headed by the country's most eminent nationalist, Sihanouk.

From Beijing, where he had been stranded by the coup that deposed him, Sihanouk in 1970 announced the formation of a Royal Government of National Union of Kampuchea (Gouvernement royal d'union nationale du Kampuchéa – GRUNK – see Appendix B). This government, he said, would be under the leadership of a broad umbrella organisation, the National United Front of Kampuchea (Front uni national du Kampuchéa – FUNK). The prestige of Sihanouk's name thus helped the Khmer Rouge in their recruitment effort. Rural peasant volunteers believed they were joining a broad-based national resistance movement, headed by the prince, against an ineffectual puppet regime in Phnom Penh. Several groups also rallied to the broad appeal of the GRUNK/FUNK. Such groups included the pro-Sihanouk Khmer Rumdo (see Appendix B), the Khmer Viet Minh, and the Khmer Loeu.

To accommodate the disparate elements that were rallying to the resistance cause, the RAK was renamed the Cambodian People's National Liberation Armed Forces (CPNLAF – see Appendix B). As this force grew in size and in proficiency, it was able to relieve North Vietnamese units of their combat burden in Cambodia. By 1973 there were reportedly no more than 5,000 North Vietnamese combat troops in Cambodia, and of this number only 2,000 to 3,000 were deployed against FANK units.

After the Chenla campaigns, FANK was unable to regain the offensive, and its operations became a series of hard-fought defensive actions against an enemy whose momentum could not be stayed. Individual unit valor and fleeting tactical successes did little to relieve the unbroken string of FANK setbacks – overrun outposts, annihilated battalions, cut-off columns, plummeting morale, exhausted supplies, steadily shrinking government territory, and enemy units that were drawing ever closer around Phnom Penh. A harbinger of future trends was discernible as early as November 1972, two-and-a-half years before the final defeat. FANK strategists at that time acknowledged the waning capability of their armed forces and redrew the Lon Nol Line. The new line of demarcation signified a profound strategic realignment because it conceded most of the country, including the rich rice-growing areas around the Tonlé Sap, to the enemy. In accordance with the redrawn Lon Nol line, FANK was committed to defend no more than the triangular corner of southeastern Cambodia, which held a majority of the population and was bounded generally by Route 4 from Phnom Penh to Kampong Saom on the west, and by Route 1 from Phnom Penh to the Vietnamese border on the east. The apex of the triangle passed just north of Odongk, the former royal capital that was to be the scene of heavy fighting later in the war. Even this retrenchment, however, turned out to be impractical, as successive engagements failed to dislodge the enemy troops south of the new defence line, and FANK increasingly found itself hard pressed from that direction as well.

By 1973 United States Department of State sources, possibly underestimating, noted that the Khmers rouges–dominated CPNLAF controlled about 60 percent of Cambodia's territory and 25 percent of the population. Despite a sustained United States bombing campaign that year to blunt the steady advance of the CPNLAF and to relieve pressure on FANK, the Khmers rouges insurgent forces were able to absorb their losses, to maintain the initiative, and to subject an increasingly demoralised and cornered FANK to unremitting pressure.

The denouement for FANK and for the Khmer Republic began on New Year's Day 1975 when the CPNLAF unleashed its final offensive. As winter turned into spring, the enemy battered the defences of Phnom Penh from every direction. Routes into the city were cut, reopened, and cut again; river convoys were forced to run a gauntlet of hostile fire to reach the beleaguered capital and finally could no longer break through; United States aircraft, in a forlorn attempt to maintain a lifeline into the city, set up an airlift from bases in Thailand. The effort worked briefly, until the airport itself was interdicted by hostile rocket fire. By early April, Phnom Penh was surrounded on all sides, and its defences were crumbling. FANK attempts to break out of the encircled city stalled in the face of intense Khmers rouges firepower. Government units were decimated, exhausted, and out of supplies; finally, they were unable to hold out any longer. The fall of the capital on 17 April, marked the demise of the Khmer Republic and the total defeat of FANK, which in the end had been totally outclassed and outfought, not by an army of guerrillas – that phenomenon so intensively studied during the period, but by a tough, disciplined, regular force in a conventional war of movement, by fire and by manoeuvre.

Cambodian Civil War

Khmers rouges' armed forces

Aircraft roundel of the Revolutionary Army of Kampuchea (RAK), 1975 to 1979.

The 68,000-member Khmers rouges–dominated CPNLAF force that completed its conquest of Cambodia in April 1975 was a highly dedicated and disciplined peasant army, trained in the rigors of guerrilla warfare as well as in full-scale combat. Its shadowy intellectual leaders, adhering to the Maoist principles of guerrilla warfare, had taken their core "fish" from only three scattered companies, when optimum conditions had been presented to them in 1970, and had propelled them through the "water" of the people in the countryside, while collecting thousands of proselytes on the way. These leaders were fiercely independent, at first grudgingly accepting training and arms from the Vietnamese – the hated traditional enemy – while on occasion violently turning on these nominal allies, behaviour that presaged the fatal conflict that was to come. When most North Vietnamese and Viet Cong combat divisions had withdrawn from the field in Cambodia at the end of 1972, the RAK had experienced phenomenal growth, reaching an estimated 50,000. Its personnel continued to arm themselves by capturing or purchasing weaponry from FANK. The insurgents marched under the banners of nationalism, of legitimacy, and of national preservation – the escutcheon of Sihanouk. In the end, they defeated an army which had a strength on paper of 230,000, but which possibly numbered as few as 150,000. FANK had been armed by the United States with military weaponry and equipment worth $US1.18 billion, an abundance of matériel that now fell into the hands of the CPNLAF.

At the beginning of the regime of Democratic Kampuchea, the CPNLAF – now renamed the RAK once again, under its long-time commander and then Minister of Defense Son Sen, had 230 battalions in 35 to 40 regiments and in 12 to 14 brigades. The command structure in units was based on three-person committees in which the political commissar ranked higher than the military commander and his deputy. The country was divided into zones and special sectors, the boundaries of which changed slightly over the years. Within these areas, the RAK's first task upon "liberation", as a calculated policy, was the peremptory execution of former FANK officers and of their families, without trial or fanfare.

The next priority was to consolidate into a national army the separate forces that were operating more or less autonomously in the various zones. The Khmers rouges units were commanded by zonal secretaries who were simultaneously party and military officers, some of whom were said to have manifested "warlord characteristics." Troops from one zone frequently were sent to another zone to enforce discipline. It was such efforts to discipline zonal secretaries and their dissident or ideologically impure cadres that gave rise to the purges that were to decimate RAK ranks, to undermine the morale of the victorious army, and to generate the seeds of rebellion. As journalist Elizabeth Becker noted, "in the end paranoia, not enemies, was responsible for bringing down the regime."

Cambodian–Vietnamese border tensions

Border tensions between Cambodia and Vietnam (aside from traditional Khmer fear and hatred of the Vietnamese) goes back to the controversy over the Brévié Line, drawn in 1939 by French colonial administrators and considered by Vietnam to be the official international boundary between the two countries. For years after the French departure, various Cambodian governments attempted to negotiate the return of Cochinchina – known in Cambodia as Kampuchea Krom, which they maintained was a French colony, not a protectorate, that had been promised to Cambodia by early French colonial authorities. Negotiations to solve the border dispute were held between 1975 and 1977, but they made no progress and were suspended. The Khmers rouges also felt an abiding distrust of the Vietnamese, who, they believed, had never renounced their determination to incorporate Cambodia into a larger, Hanoi-dominated Indochina federation.

Clashes between the RAK and Vietnam People's Army began in Cambodia as early as 1970, when there were reported incidents of Khmer Rouge units firing on North Vietnamese. Reports continued of engagements of growing intensity, particularly after 1973. The North Vietnamese, because they urgently needed sanctuaries in Cambodia to pursue their war in South Vietnam, chose to ignore the incidents and were still prepared, at the end of Cambodia's long civil war, to send sapper and artillery groups to help the Cambodian People's National Liberation Armed Forces (CPNLAF) take Phnom Penh. After the communist victories of April and May 1975, clashes between Vietnamese and Khmer Rouge units centred on the border. Skirmishing began about a month after the fall of Phnom Penh, when Hanoi accused the Khmers rouges of trying to seize Phú Quốc Island and of making forays into several Vietnamese border provinces.

Ironically, some analysts believe that the Khmer Rouge would have made more noise about their offshore claims had it not been for the destruction by the United States of their air force and much of their navy during the Mayagüez incident. On 12 May 1975, a Khmer Rouge sector commander, zealously asserting Cambodia's territorial rights in the Gulf of Thailand, boarded and captured the American container ship S.S. Mayagüez, which carried a crew of forty, near the island of Wai (which later fell under Vietnamese jurisdiction). Failing to receive a timely response to demands for return of the ship, Washington notified the UN and invoked the right to self-defense under Article 51 of the UN Charter. The ensuing four-day engagement involved US bombing raids on the airfield at Ream and on the port of Kompong Saom, as well as naval barrages and a Marine assault on the nearby island of Kaoh Tang. On orders from the Khmer Rouge leadership, the Mayagüez crew was released unharmed and was returned to United States custody.

Deteriorating relations between Cambodia and Vietnam reached a crescendo of recrimination when, on 31 December 1977, Radio Phnom Penh, citing "ferocious and barbarous aggression launched by the 90,000 Vietnamese aggressor forces against Democratic Kampuchea", denounced the "so-called Socialist Republic of Vietnam" and announced the "temporary severance" of diplomatic relations. Rhetorical exchanges between the two sides became more acrimonious, and border skirmishes involving Cambodian and Vietnamese units erupted into pitched battles in the summer and the fall of 1978. Major engagements were reported in the Parrot's Beak (part of Svay Rieng Province), in the Fishhook (part of Kampong Cham Province), and in Ratanakiri Province. In an effort to court world public opinion, in September 1978 the Ministry of Foreign Affairs of Democratic Kampuchea published its so-called "Black Book", the Black Paper: Facts and Evidence of Aggression and Annexation against Kampuchea. The tract denounced Vietnam's "true nature" as that of "aggressor, annexationist and swallower of other countries' territories."

In November 1978, rhetoric was succeeded by full-scale action: Vietnamese forces launched a sustained operation on Cambodian soil in the area of Snuol and Memot (both in Kratié Province). This action cleared a liberated zone where anti-Khmer Rouge Cambodians could launch a broad-based political movement that would offer an alternative to the odious Pol Pot regime. Proclamation of this movement, the Kampuchean (or Khmer) National United Front for National Salvation (KNUFNS), took place in a rubber plantation clearing on 2 December 1978, amid rigid security provided by heavily armed Vietnamese units reinforced with airdefense weapons.

Vietnamese invasion of Cambodia

The public unveiling of the KNUFNS dashed any remaining expectations that Cambodian-Vietnamese disagreements could be solved without further armed conflict, because the Hanoi-backed front openly called for the ouster of the "reactionary Pol Pot–Ieng Sary clique." Because the KNUFNS was far too weak to topple the regime of Democratic Kampuchea, virtually the entire combat burden would fall on Vietnamese forces, which, for this purpose, had been steadily building up troop strength on the border during the preceding months.

Nervous Khmer Rouge leaders in Phnom Penh did not have long to wait after the KNUFNS announcement, for, on 25 December 1978, Hanoi launched its offensive with twelve to fourteen divisions and three Khmer regiments (that later would form the nucleus of the KPRAF), a total invasion force comprising some 100,000 people. Vietnamese units struck across the Cambodian frontier in five spearheads that thrust initially into northeastern Cambodia. One task force drove west from Buon Me Thuot (in Dac Lac Province, Vietnam) along Route 13 and Route 14 to capture Kracheh City (the capital of Kracheh Province). A second column attacked west from Pleiku (in Gia Lai–Cong Tum Province, Vietnam), and followed the circuitous Route 19 to capture Stoeng Treng City (the capital of Stoeng Treng Province). In thus concentrating its initial thrusts in the northeast, Hanoi may have had several objectives. One of these may have been to capture quickly substantial expanses of the Cambodian territory that had been an early spawning ground for the Khmer Rouge and its fledgling RAK in the late 1960s. The remoteness of this region would have rendered it difficult to dislodge Vietnamese forces, no matter what the outcome of the war. An early occupation also would have preempted Khmer Rouge units, if they were pressed harder elsewhere, from falling back to this area where they might have enjoyed a measure of public support. The attacks in the northeast also may have been intended to confuse the leadership of Democratic Kampuchea about where the full brunt of the Vietnamese offensive would fall.

Khmers rouges commanders were not deceived by the Vietnamese thrusts toward Kratié and Stung Treng, however, and made no attempt to reinforce the northeast. Instead, they erected their main defence line in an arc across the flat, rice-growing plains of southeastern Cambodia, astride the most probable Vietnamese axes of advance. Their calculation of Vietnamese intentions proved correct, as Hanoi's forces unleashed the full weight of their offensive in this area. From Vietnam's Tây Ninh Province, heavily armed Vietnamese units drove along the axis of Route 7 toward their objective, the river port of Kampong Cham. Farther south, Vietnamese units with air support attacked along Route 1, in the direction of Prek Khsay (near Neak Luong), the Mekong River gateway to Phnom Penh. The fifth and final Vietnamese spearhead drove west from Ha Tien, Vietnam, to capture the ports of Kampot and Kompong Som, and thus to prevent the resupply by sea of retreating Khmer Rouge forces.

Resistance to the invading Vietnamese units by the RAK could have been suicidal, given the disregard for human life previously displayed by the forces of Democratic Kampuchea. Instead, heavy fighting was localised. Major engagements were fought before Kampong Cham and Prek Khsay and at Tani, inland from the coast of Kampot Province. RAK units, already deprived of experienced commanders by party purges, withered under sustained pounding by Vietnamese artillery and air strikes, and many of them simply scattered before the Vietnamese offensive, some to regroup later in western Cambodia.

By 5 January 1979, the main Vietnamese spearheads had driven to the eastern banks of the Mekong River. Incomplete evidence hints that the Vietnamese offensive originally may have intended to go no farther. The way to Phnom Penh lay open, however, because the Khmer Rouge units were falling back. Vietnamese forces paused briefly, perhaps to wait for bridging and ferrying equipment and the latest orders from Hanoi, then proceeded to carry out the final assault on Phnom Penh. Khmer Rouge leaders elected not to defend the city, and it fell on 7 January.

After the fall of the capital, Vietnamese units continued their advance in two columns into western Cambodia, capturing Battambang and Siemréap. The columns met at Sisophon and drove on to the Thai border, where there was heavy fighting in March and in April. In the meantime, some remaining Khmers rouges units offered scattered resistance before they melted away into less accessible areas. There the Khmer rouges leaders soon rekindled an insurgency against the new government in power, just as they had in the late 1960s, and insecurity persisted in the countryside in spite of the continued Vietnamese presence.

On the diplomatic front, Vietnam, maintaining it had no troops in Cambodia and attributing the lightning-like victory to the KNUFNS, at first denied responsibility for the invasion. When called before the UN Security Council, however, Hanoi's representative, tacitly admitting the presence of Vietnam and citing numerous Western press reports of Pol Pot's genocidal actions, implied that his country had overthrown the Pol Pot regime in the name of humanitarian and human rights.

The Vietnamese sweeping through Cambodia produced an unprecedented level of turmoil on the Thai border, as disorganised and by-passed Khmers rouges units and civilian refugees fled before their advancing enemy. Amid this chaos, in 1979, two anti-Vietnamese insurgent movements, besides the Khmer rouges, came into being. The first of these was the Khmer People's National Liberation Armed Forces (KPNLAF – see Appendix B), the armed wing of the Khmer People's National Liberation Front (KPNLF – see Appendix B), which gave allegiance to Son Sann, a non-communist, perennial cabinet minister in successive Sihanouk administrations. The other was the Sihanouk National Army (Armée nationale sihanoukiste – ANS – see Appendix B), the armed wing of the National United Front for an Independent, Neutral, Peaceful, and Co-operative Cambodia (Front uni national pour un Cambodge indépendant, neutre, pacifique, et coopératif – FUNCINPEC – see Appendix B), which owed allegiance to Sihanouk. Fighting independently, these noncommunist guerrilla movements and the Khmers rouges fomented continuous rebellion in the early 1980s that could not be quelled, despite a substantial Vietnamese military commitment to this purpose. Operating from refugee camps on the Thai frontier, the insurgents made forays into the Cambodian border provinces and kept the countryside in a permanent state of insecurity.

In the 1984 to 1985 dry season, the Vietnamese military command in Cambodia, frustrated because of depredations by the guerrillas, undertook a sustained offensive to dislodge them from their sanctuaries in the refugee camps. These installations were pounded by artillery and were overrun by Vietnamese tactical units. The operation, which was intended to cripple the Khmers rouges guerrillas, had the opposite effect, however. It drove them away from the border, and they undertook prolonged forays deeper into the Cambodian interior.

To restrict guerrilla activity, the Vietnamese erected a physical barrier on the Thai-Cambodian border. Code-named Project K-5, the effort consisted of clearing jungle growth; of erecting obstacles, such as ditches, barbed wire, and minefields; and of building a road parallel to the border. Construction of the project, which began in 1985, was performed by corvée labour. All districts in Cambodia were tasked to provide able-bodied males for tours of duty on the project that ranged from three to six months. Living conditions were primitive in the construction camps, and the diet was inadequate; the area was malarial, and unexploded ordnance from past conflicts was a constant threat. The barrier was completed in 1987 at an unrecorded cost in Cambodian lives. Preliminary indications shortly thereafter revealed that it was having little effect on guerrilla movements to and from the Cambodian interior.

Military developments in postwar Cambodia

Tenuous security

In the late 1980s, a Vietnamese military contingent of 140,000 troops, and a Cambodian force – a surrogate for the Vietnamese – of 30,000 to 35,000 troops, which comprised the KPRAF of the new government in Phnom Penh, maintained tenuous control over the heartland of Cambodia. This territory included the population centres, the fertile rice-growing area around the Tonlé Sap, and the main arteries of communication (see Population, ch. 2; Agriculture, and Transportation and Communications, ch. 3). The combined Vietnamese–KPRAF military effort was opposed by disunited and factious but persistent insurgent forces belonging to each of the three components of the tripartite Coalition Government of Democratic Kampuchea (CGDK – see Coalition Government of Democratic Kampuchea, ch. 4). The insurgents had the capability to conduct long-range combat or reconnaissance patrols with as many as 100 troops. They could engage in small-scale propaganda missions, raids, and ambushes against poorly armed targets, such as militia outposts, and in sabotage against stationary, infrastructural objectives, such as bridges and railroad tracks. They lacked sufficient troop strength, heavy weapons, trained leadership, and dependable logistical support, however, for sustained combat operations. From their jungle havens deep within the country and from their bases near the Thai border, the insurgents were reputed to range widely throughout Cambodia. Verifiable guerrilla actions, however, were confined to the northwestern provinces of Battambang and Siemreáp–Oddar Meanchey (the two provinces were combined into one by the government of the People's Republic of Kampuchea prior to 1980), which continued to be the centres of insurgent activity. Most foreign observers in the late 1980s assessed the military situation as being at a stalemate. The rebels lacked the capability, actual or potential, to drive out the Vietnamese occupation force, while the combined Vietnamese–KPRAF armies, at foreseeable force and equipment levels, were incapable of destroying the CGDK guerrilla units.

Coalition government resistance forces

The tripartite CGDK opposed both the Vietnamese military presence in Cambodia and the government of the People's Republic of Kampuchea that had been installed in Phnom Penh by Hanoi. Each component of the coalition maintained its own force of armed combatants (see fig. 13). Divided by deep-seated animosities among their leaders, these three distinctive and autonomous military forces were brought into a reluctant and uneasy coalition as a result of diplomatic activity by the Association of Southeast Asian Nations (ASEAN). The common goal of contesting the Vietnamese occupation, however, could not bridge the noncommunist coalition partners' deep suspicion toward the renascent Khmer Rouge. Throughout the 1980s, the three combatant forces remained unintegrated, and each maintained separate bases, command structures, and operational planning. An effort by ASEAN to unite the three resistance forces on the Thai border resulted, in May 1984, in the creation on paper of the Permanent Military Coordinating Committee, which apparently never functioned.

Limited tactical co-operation, however, occasionally was reported among the various coalition partners. In one rare example, the three forces participated jointly in a major operation in Batdambang Province in early 1986. Usually, Khmer Rouge units, under their shadowy zonal commanders, remained aloof from their coalition partners and, on occasion, even attacked their military forces and inflicted casualties. Such interfactional clashes were the subject of several complaints by Sihanouk, who charged over the years that Khmer Rouge guerrillas had "repeatedly ambushed and killed [his] troops." These allegations were the principal reason why he chose to step down from the presidency of the CGDK on a leave of absence in May 1987.

National Army of Democratic Kampuchea

The National Army of Democratic Kampuchea (NADK – see Appendix B) was the successor to the RAK of the Khmer Rouge, the name change having gone into effect in December 1979, in an apparent public relations effort that later saw the dissolution of the Kampuchean (or Khmer) Communist Party (KCP – see Appendix B), (replaced by the Party of Democratic Kampuchea, or PDK – see Appendix B) and the purported retirement of Pol Pot to an advisory role in 1985. NADK forces consisted of former RAK troops – large numbers of whom had escaped the 1978 to 1979 Vietnamese invasion of Cambodia – as well as conscripts coerced into submission during the Khmer Rouge retreat and new volunteers or recruits either pressed into service during in-country raids or drawn from among refugee groups. The New York Times reported in June 1987 that "the Khmer Rouge army is believed to be having some success in its recruitment, not only among the refugees in its camps but within Vietnamese-controlled Cambodia." The NADK did not make personnel figures public, but estimates by military observers and by journalists generally ranged between 40,000 and 50,000 combatants.

In 1987 the opinion that the NADK was "the only effective fighting force" opposing the Vietnamese was more often expressed by foreign observers. In an interview published in the United States in May 1987, Sihanouk reportedly said, "without the Khmer Rouge, we have no credibility on the battlefield... [they are]... the only credible military force."

During the 1980s, the Khmers rouges leadership, composed of party cadres who doubled as military commanders, remained fairly constant. Pol Pot retained an ambiguous but presumably prominent position in the hierarchy, although he was nominally replaced as commander-in-chief of the NADK by Son Sen, who had also been a student in Paris, and who had gone underground with him in 1963. There were reports of factions in the NADK, such as one loyal to Khieu Samphan, prime minister of the defunct regime of Democratic Kampuchea, and his deputy Ieng Sary, and another identified with Pol Pot and Ta Mok (the Southwestern Zone commander who conducted extensive purges of party ranks in Cambodia in 1977 to 1978). Although led by party and military veterans, the NADK combatants were reportedly "less experienced, less motivated, and younger" than those the Vietnamese had faced in previous encounters. Nevertheless, the new Khmer Rouge recruits still were "hardy and lower class", and tougher than the noncommunist combatants.

During forays into Cambodia, NADK units employed terror tactics against Khmer civilians, including murder and destruction of economic resources. Such success as they achieved in recruiting was apparently owed to traditional Cambodian hatred of the Vietnamese invader, although there were reports that some of the peasantry would have preferred to endure a continued Vietnamese occupation rather than to suffer a return to Khmer Rouge rule.

The Khmers rouges divided the country into four military zones that functioned virtually autonomously under their respective commanders. Within these four zones, three areas – the provinces around the Tonlé Sap, the western border of Cambodia, and the remainder of the country – were sites of NADK tactical operations. It was the first area, the heartland of Cambodia, that the NADK viewed as the "Achilles' heel of the Vietnamese enemy", where NADK military efforts were concentrated.

NADK units managed to keep the main routes linking Phnom Penh to western Cambodia "in a permanent state of insecurity", according to a senior Vietnamese military observer; traffic to and from the seaport of Kampong Saom was obliged to move in convoys. Both highways and railroads from the capital were interdicted intermittently because of guerrilla activity. Officials in Phnom Penh told a Western correspondent in 1987 that the Khmer Rouge were then operating in small insurgent groups inside Cambodia in a battle for the villages, rather than fighting from the Thai border area, as had been the case prior to the 1984 to 1985 Vietnamese dry season offensive. In carrying the war to the countryside, the NADK demonstrated that it had gone on the strategic defensive, that is, that it would adhere to a doctrine of guerrilla warfare until the balance of forces was about equal. If this parity were to be achieved, NADK strategists presumably would then switch to offensive operations.

In carrying on its protracted insurgency, the NADK received the bulk of its military equipment and financing from China, which had supported the previous regime of Democratic Kampuchea. One pro-Beijing source put the level of Chinese aid to the NADK at US$1 million a month. Another source, although it did not give a breakdown, set the total level of Chinese assistance, to all the resistance factions, at somewhere between US$60 million and US$100 million a year.

The Chinese weaponry observed in the possession of NADK combatants included Type 56 assault rifles, Type 56 light machine guns, RPG (rocket-propelled grenade) launchers, recoilless rifles, and anti-personnel mines. NADK guerrillas usually were seen garbed in dark green Chinese fatigues and soft "Mao caps" without insignia. No markings or patches were evident on guerrilla uniforms, although the NADK had promulgated a hierarchy of ranks with distinctive insignias in 1981.

To keep troops and supplies moving into the combat zone, the NADK, according to Vietnamese sources, followed two infiltration routes. One of them ran south from Thailand through the Dangrek Escarpment into Cambodia. The second ran north from Tra, a minor Thai seaport that may have been an unloading point for Chinese supplies for the Khmer Rouge. In spite of substantial Chinese material assistance, however, the NADK could not maintain the logistical supply line needed to conduct a sustained military campaign.

Khmer People's National Liberation Armed Forces

The Khmer People's National Liberation Armed Forces (KPNLAF), the military component of the Khmer People's National Liberation Front (KPNLF), was formed in March 1979 from various anticommunist groups concentrated near the Thai border with Cambodia, which were opposed to Pol Pot's Democratic Kampuchea. Many had become essentially warlord bands, engaging more in trade and in internecine fighting than in combat operations. They were brought together by General Dien Del, a former career officer of the Khmer Republic, who became chief of the KPNLAF General Staff.

The KPNLAF was loyal to Son Sann, a former Sihanouk minister and the founder of the KPNLF political movement. Because of Son Sann's noncommunist credentials, the KPNLAF offered an alternative to those Cambodians who could support neither Hanoi nor the Khmer Rouge, and it quickly became the second largest guerrilla force in the country. By mid-1981, with about 7,000 personnel under arms, it was able to protect its refugee camps and occasionally to conduct forays into Cambodia.

Two developments in the mid-1980s, however, greatly diminished KPNLAF capabilities as a fighting force. The first of these was the Vietnamese dry season offensive of 1984 to 1985, which dislodged these guerrillas from their havens on the Thai–Cambodian border. All three insurgent forces were affected by this setback, but the KPNLAF proved less able than the others to sustain the reversal and less flexible in adapting to new conditions. Critical sources noted that the KPNLAF had "made no significant contribution to the [1984-85] dry season fighting against the Vietnamese" and that its combatants had been "virtually immobilized by the loss of their camps." The second development, equally harmful to the KPNLAF cause, was the dispute that broke out among the top leaders. Following the loss of the border camps, contemporary reports noted that "open revolt" had broken out among guerrilla commanders over the "dictatorial ways" of Son Sann, who had continued as president of the KPNLF, and his "interference in military matters." The crisis resulted in the virtual paralysis of the KPNLAF on a temporary basis.

Observers also reported that, as a result of the KPNLAF leadership dispute, members of guerrilla units had returned to the Thai border from the Cambodian interior to await the outcome of the controversy. There were desertions, and discipline became an increasingly serious problem. KPNLAF soldiers became suspect when it was reported that gangs of Khmer bandits had attacked Thai vehicles and buses, and had sometimes abducted or abused passengers. There had long been allegations that Khmer insurgents on the border engaged in black marketing and in other criminal activity.

In 1987 estimates of KPNLAF strength varied widely. At the upper limit, a widely quoted total was 14,000 personnel. In view of the leadership dispute that debilitated the movement in 1985 and in 1986 and prevented its subsequent growth, this figure probably was a considerable exaggeration. A more realistic total was about 8,000 combatants, and KPNLAF leaders expressed the hope that an earnest recruitment drive then beginning might increase the movement's strength to 18,000 by the end of the year.

In accordance with its recruitment and reorganisation plans, the KPNLAF divided Cambodia into nine military regions, or operational zones. The force's chain of command was headed by a general officer (in 1987, by General Sak Sutsakhan) who functioned as commander in chief. Reporting to him was a chief of staff, who exercised responsibility over four deputy chiefs of staff. Each of these latter officers was in charge of one of four sections dealing respectively with military operations, general administration, logistical affairs, and planning/psychological operations. At the next subordinate echelon were two or three assistant chiefs of staff, whose functions were undefined. Military units of the KPNLAF were described as battalions, regiments, and brigades, operating presumably from semi-permanent camps in inaccessible areas. Combat elements reportedly, were operating in three provinces of western Cambodia: Battambang, Siemréap–Oddar Meanchey, and Pursat. Actual deployment in the latter province, long a Khmer Rouge stronghold, however, was in question.

The KPNLAF, like the NADK, received most of its military assistance from China. Some aid and training was granted by ASEAN nations, however, especially by Singapore and by Malaysia. In late 1986, the Chinese reportedly delivered a shipment of rocket launchers; this was the first time the KPNLAF was equipped with effective antitank weapons.

KPNLAF combatants sometimes were garbed in camouflage fatigues and combat boots, both probably of noncommunist origin. At other times, they were observed, while on operations, to be wearing merely odds and ends of clothing, gleaned in refugee camps, rather than uniforms. No rank or branch insignia were discernible, but KPNLAF troops frequently wore plastic-laminated chest pocket badges with a photo of Son Sann and the noncommunist Cambodian flag.

Armée nationale sihanoukiste

The smaller of the two non-communist resistance groups, the Armée national sihanoukiste (ANS) owed allegiance to Sihanouk. It was the armed adjunct of FUNCINPEC, which rallied Sihanouk supporters clustered on the Thai border. The force was formed in June 1981, by consolidating the Movement for the National Liberation of Kampuchea (Mouvement pour la libération nationale du Kampuchea – MOULINAKA – see Appendix B) and at least two other armed groups of Sihanouk supporters grouped on the Thai border. These groups existed at first in conditions of near penury, their members poorly armed and equipped as well as half starved. Following the proclamation of the Coalition Government of Democratic Kampuchea, international support consisting of armaments, supplies, and other nonlethal aid, principally from the ASEAN countries and from China, began to transform the ANS into a more effective movement. In about 1986 to 1987, it became the principal noncommunist insurgent force by default when the KPNLAF slipped from that position because of its internal leadership dispute.

No authoritative figures for the personnel strength of the ANS were available in the late 1980s. The most frequently cited totals ranged from a low of 7,000 to a high of 11,000 combatants. The former figure was quoted by Sihanouk, the latter by Sihanouk's son, Prince Norodom Ranariddh, some time afterward. In late 1987, Sihanouk also declared that the ANS maintained "8,500 fighters permanently inside Cambodia." (This number would not necessarily include headquarters, staff, and support elements on the Thai border.)

The ANS was organised into a command structure and manoeuvre elements. The command structure was headed by the commander in chief of the ANS, who was assisted by both a chief and a deputy chief of staff. In 1987 the positions of commander and of chief of staff were held concurrently by Prince Norodom Ranariddh, and that of deputy chief of staff by Major General Prince Norodom Chakrapong, both middle-aged sons of Sihanouk. Maneuver elements consisted of battalions, grouped under the first through the sixth brigades. There were, in addition, four independent regiments, at least one reportedly composed of Khmer Rouge deserters who had rallied to Sihanouk's cause, and five independent commando groups, each composed of about seventy personnel.

Following the Vietnamese dry season offensive of 1984 to 1985, the ANS made a major effort to deploy its fighters away from the border camps and more deeply into Cambodia. In 1987 according to Sihanouk, ANS combatants were deployed in five Cambodian provinces, including Batdambang and Siemreab-Otdar Meanchey on the western border with Thailand. Limited deployments also were reported as far east as Kampong Thum.

Photographic evidence indicated that the ANS, like the KPNLAF, was equipped principally with Chinese weapons. This included Type 56 assault rifles, light machine guns, RPG (rocket-propelled grenade) launchers, and recoilless rifles. ANS combatants were dressed in a panoply of uniforms, some of them of ASEAN origin. These included camouflage fatigues and (T-shirts), visored caps, and combat boots. Indications of rank were not evident on uniforms; however, ANS members sometimes wore plastic-laminated chest pocket badges bearing a photograph of Sihanouk and a noncommunist Cambodian flag.

Kampuchean, or Khmer, People's Revolutionary Armed Forces

The Kampuchean (or Khmer) People's Revolutionary Armed Forces (KPRAF) constituted the regular forces of the pro-Hanoi People's Republic of Kampuchea (PRK). Soon after the downfall of the Khmer Rouge, two reasons for the necessity of such forces became apparent to the PRK's Vietnamese mentors when they installed the new Cambodian government in early 1979. First, if the new administration in Phnom Penh was to project internationally the image of being a legitimate sovereign state, it would need a national army of its own apart from the Vietnamese forces. Second, if the People's Army of Vietnam was not to have to shoulder indefinitely its internal security mission in Cambodia, it would need to develop a Khmer military force that could be put in place as a surrogate for Vietnamese troops. Raising such an indigenous force presented no insurmountable obstacle for Hanoi at the time because several precedents already had been established. In Laos, the Vietnamese armed forces maintained a close training and co-ordinating relationship with their Laotian counterparts as a result of Hanoi's military presence in the country. In Cambodia, Vietnam had been a mainstay for Khmer communist factions since 1954. The People's Army of Vietnam also had helped train Pol Pot's RAK and its successor, the CPNLAF, following the coup that deposed Sihanouk in 1970. More recently, Hanoi had helped raise and train a few, probably battalion-sized, regiments of Khmer troops that had fought alongside the Vietnamese during the invasion of Cambodia. With further Vietnamese tutelage, these Khmer units became the nucleus of a national army. From such ad hoc beginnings, the KPRAF grew as a military force and eventually gained its position as an instrument of both the party and the state. This development, however, was carefully shielded from the scrutiny of outsiders, and much that could be concluded about the armed forces of the PRK was based on analysis rather than incontrovertible hard data.

Foreign troops and advisers

In the late 1980s, Vietnamese units stationed in Cambodia represented a military force that had broken away from its revolutionary tradition and had become an army of occupation, a dramatic role change in view of the fact that its most formidable adversaries, the Khmer Rouge, were fellow communists and former allies. Consistently designated by Hanoi as "the Vietnamese volunteer army in Kampuchea", the Vietnamese force, comprising some ten to twelve divisions, was made up of conscripts who supported a "regime of military administration."

Military units totalling as many as 200,000 troops invaded Cambodia at the end of 1978 to eradicate the Khmer Rouge regime of Democratic Kampuchea and to install a more pliant government in Phnom Penh. After several years, Vietnam ostensibly began to decrease the size of its military contingent in Cambodia. The first recorded, but unannounced, withdrawal occurred in June 1981, when Vietnam's 137th Division returned home. In July 1982, Hanoi announced publicly that as an "act of goodwill" it would withdraw an unspecified number of troops from Cambodia. These withdrawals became annual occurrences. In 1986 Vietnamese sources announced a pullout of 12,000 troops. In November 1987, an additional 20,000 Vietnamese military personnel were withdrawn. These retrenchments were conducted with considerable publicity and fanfare, including departure ceremonies in Phnom Penh and featuring medals for commanders and citations for units. Skeptics, however, contended that these movements were merely troop rotations. A 1987 study conducted by Chulalongkorn University in Bangkok reached the same conclusion, after its researchers interviewed groups of Vietnamese defectors.

Hanoi publicly committed itself to withdraw its occupation forces by 1990. It first announced this decision following an August 1985 meeting of Vietnamese, Laotian, and Cambodian foreign ministers. The commitment to a pullout engendered continuing discussion, both by foreign observers and by Indochinese participants. What emerged was the clarifying qualification that a total Vietnamese military withdrawal was contingent upon the progress of pacification in Cambodia and upon the ability of the KPRAF to contain the insurgent threat without Vietnamese assistance. Prime Minister Hun Sen declared in a May 1987 interview that "if the situation evolves as is, we are hopeful that by 1990 all Vietnamese troops will be withdrawn ... [but] if the troop withdrawal will be taken advantage of, we will have to negotiate to take appropriate measures...." Shortly thereafter, a KPRAF battalion commander told a Phnom Penh press conference that "Vietnamese forces could remain in Cambodia beyond 1990, if the Khmer Rouge resistance continues to pose a threat." In an interview with a Western correspondent, Vietnamese Foreign Minister Nguyen Co Thach repeated the 1990 withdrawal pledge, insisting that only foreign military intervention could convince Hanoi to change its plans. Some ASEAN and Western observers greeted declarations of a total pullout by 1990 with incredulity. Departing Vietnamese units reportedly left equipment behind in Cambodia, and it was suggested that they easily could return if it looked as though a province might be lost.

As Hanoi's military presence in Cambodia approached its ninth year, it appeared that the Vietnamese troops stationed there were not frontline veterans. Most of Vietnam's main force units and its best troops were deployed in the Red River Delta or on Vietnam's northern border to contain any armed threat from China. Units in Cambodia were composed of conscripts from the southern provinces of Vietnam, or, according to refugee accounts, of military misfits and "troublemakers." Some Vietnamese defectors in Thailand declared that they had volunteered for military service to get out of Vietnam and to have an opportunity for resettlement in third countries.

Vietnam's presence in Cambodia reportedly consumed 40 to 50 percent of Hanoi's military budget. Although substantial portions of the cost had been underwritten by Soviet grant aid, Vietnamese troops in Cambodia apparently were on short rations. Radio Hanoi reportedly commented on troops "dressed in rags, puritanically fed, and mostly disease ridden." The parlous state of Vietnamese forces in Cambodia also was the subject of a report by the director of an Hanoi military medical institute. According to media accounts, the report acknowledged that Vietnamese troops in the country suffered from widespread and serious malnutrition and that beriberi occurred in epidemic proportions.

The Vietnamese military headquarters in Cambodia was located at Chamka Morn in Phnom Penh. In the mid-1980s, it was responsible to the Vietnamese Fourth Corps commander, at that time General Le Duc Anh (subsequently promoted to minister of national defence). Vietnamese military authorities divided Cambodia into four military regions. These areas probably coincided with KPRAF regions. Each of these regions, in turn, corresponded to a Vietnamese military front that exercised tactical responsibility over it. The four Vietnamese military fronts were Front 479, headquartered at Barai Toek Thla Airport, Siemreab-Otdar Meanchey Province; Front 579, at Stoeng Treng City, Stoeng Treng Province; Front 779, at the Chhupp rubber plantation, Kampong Cham Province; and Front 979, at Somrong Tong, Kampong Spoe Province. Front 479 was considered the most critical because of heavy insurgent activity in the area. A Special Military Administrative Zone was also created, comprising the vital heartland of the country around the Tonlé Sap and the alluvial plain to the southeast. The relationship of the zone to the military regions and to the fronts was undetermined. Along the Cambodian coast, the Vietnamese established another type of military jurisdiction. Naval Zone Five comprised the shore lines of Kaoh Kong and Kampot provinces and their contiguous territorial waters. The headquarters of the naval zone was at Kampong Saom.

Vietnamese military advisers also were detached to serve with KPRAF main and provincial forces down to the battalion, and perhaps even the company, level. The functions and the chain of command of these advisers remained unknown, except that it could be assumed that they reported to the Vietnamese military region or front headquarters.

References

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