Introduction
The Cambodian Civil War was a conflict that pitted the forces of the Communist Party of Kampuchea (known as the Khmer Rouge) and their allies the Democratic Republic of Vietnam (North Vietnam) and the Viet Cong against the government forces of Cambodia (after October 1970, the Khmer Republic), which were supported by the United States (U.S.) and the Republic of Vietnam (South Vietnam).
The struggle was exacerbated by the influence and actions of the allies of the two warring sides. People's Army of Vietnam (North Vietnamese Army) involvement was designed to protect its Base Areas and sanctuaries in eastern Cambodia, without which the prosecution of its military effort in South Vietnam would have been more difficult. Then following the Cambodian coup of 1970, the North Vietnamese Army's attempt to overrun the entire country in March–April 1970 plunged Cambodia into civil war. The U.S. was motivated by the desire to buy time for its withdrawal from Southeast Asia, to protect its ally in South Vietnam, and to prevent the spread of communism to Cambodia. American and both South and North Vietnamese forces directly participated (at one time or another) in the fighting. The central government was mainly assisted by the application of massive U.S. aerial bombing campaigns and direct material
and financial aid.
After five years of savage fighting, the Republican government was defeated on 17 April 1975 when the victorious Khmer Rouge proclaimed the establishment of Democratic Kampuchea. Thus, it has been argued that the US intervention in Cambodia contributed to the eventual seizure of power by the Khmer Rouge, that grew from 14,000 in number in 1970 to 70,000 in 1975. This view has been disputed, with documents uncovered from the Soviet archives revealing that the North Vietnamese invasion of 1970 was launched at the explicit request of the Khmer Rouge following negotiations with Nuon Chea. The conflict, although an indigenous civil war, was considered to be part of the larger Vietnam War (1959–1975) that also consumed the neighboring Kingdom of Laos, South Vietnam, and North Vietnam. This civil war led to the Cambodian Genocide, one of the bloodiest in history.
The Cambodian coup of 1970
The Cambodian coup of 1970 refers to the removal of the Cambodian Head of State, Prince Norodom Sihanouk, after a vote in the National Assembly on 18 March 1970. Emergency powers were subsequently invoked by the Prime Minister Lon Nol, who became effective head of state. The coup led ultimately to the proclamation of the Khmer Republic (République khmère) later that year, and was a turning point in the Cambodian Civil War. Not a monarchy any longer, Cambodia received the semi-official appellation "État du Cambodge" (State of Cambodia) in the intervening six months after the coup, until the republic was proclaimed.
It also marked the point at which Cambodia became substantially involved in the Second Indochina War, as Lon Nol issued an ultimatum to Vietnamese forces to leave Cambodia.
Background
For more details on this topic, see Cambodia under Sihanouk (1954–1970).
Since independence from France in 1954, Cambodia had been led by Prince Norodom Sihanouk, whose Sangkum political movement had retained power after winning the 1955 parliamentary election.
In 1963, Sihanouk had forced the National Assembly to approve a
constitutional amendment that made him head of state with no fixed term
of office. He had retained domestic power through a combination of
political manipulation, intimidation, patronage, and careful balancing
of left- and right-wing elements within his government; whilst placating
the right with nationalist rhetoric, he appropriated much of the
language of socialism to marginalize the Cambodian communist movement,
who he proprietorially referred to as the Khmers Rouges ("Red Khmers").With the Second Indochina War escalating, Sihanouk's balancing act between left and right became harder to maintain. Cross-border smuggling of rice also began to have a serious effect on the Cambodian economy. In the Cambodian elections of 1966, the usual Sangkum policy of having one candidate in each electoral district was abandoned; there was a huge swing to the right, especially as left-wing deputies had to compete directly with members of the traditional elite, who were able to use their local influence.[3] Although a few communists within the Sangkum – such as Hou Yuon and Khieu Samphan – chose to stand, most leftists were decisively defeated. Lon Nol, a rightist who had been a longstanding associate of Sihanouk, became Prime Minister.
By 1969, Lon Nol and the rightists were growing increasingly frustrated with Sihanouk. Although the basis for this was partly economic, political considerations were also involved. In particular, the nationalist and anti-communist sensibilities of Lon Nol and his associates meant that Sihanouk's policy of semi-toleration of Viet Cong and Vietnam People's Army activity within Cambodian borders was unacceptable; Sihanouk, during his swing to the left in 1963–66, had negotiated a secret arrangement with Hanoi whereby in return for the guaranteed purchase of rice at inflated prices, the port of Sihanoukville was opened for weapons shipments to the Viet Cong. As well as the rightist nationalists, the liberal modernising elements within the Sangkum, headed by In Tam, had also become increasingly alienated by Sihanouk's autocratic style.
There is evidence that during 1969 Lon Nol approached the US military establishment to gauge military support for any action against Sihanouk. Lon Nol's appointee as deputy Prime Minister, Prince Sisowath Sirik Matak – a US-friendly nationalist and leader of the Cambodian business community – is thought to have suggested that Sihanouk should be assassinated, though Lon Nol rejected this plan as "criminal insanity".Sihanouk himself thought that Sirik Matak (who he characterised as a jealous rival claimant to the Cambodian throne) backed by the CIA, and in contact with exiled Sihanouk opponent Son Ngoc Thanh, had suggested the coup plan to Lon Nol in 1969. CIA involvement in the coup plot remains unproven, and Henry Kissinger later claimed that events would take the US government by surprise, but it seems likely that at least some military intelligence agents were partly culpable. It is also known that the US military had drawn up plans for an invasion of Cambodia in 1966-7, and were upset that Lyndon B. Johnson would not approve them. Declassified documents indicate that, as late as March 1970, the Nixon administration was hoping to garner "friendly relations" with Sihanouk.
