Cambodian campaign
The Cambodian campaign was a series of military operations conducted in eastern Cambodia in mid-1970 by South Vietnam and the United States as an expansion of the Vietnam War and the Cambodian Civil War. Thirteen operations were conducted by the Army of the Republic of Vietnam between April 29 and July 22 and by U.S. forces between May 1 and June 30, 1970.
The objective of the campaign was the defeat of the approximately 40,000 troops of the People's Army of Vietnam and the Viet Cong in the eastern border regions of Cambodia. Cambodian neutrality and military weakness made its territory a safe zone where PAVN/VC forces could establish bases for operations across the border. With the US shifting toward a policy of Vietnamization and withdrawal, it sought to shore up the South Vietnamese government by eliminating the cross-border threat.
A change in the Cambodian government allowed an opportunity to destroy the bases in 1970, when Prince Norodom Sihanouk was deposed and replaced by pro-U.S. General Lon Nol. A series of South Vietnamese–Khmer Republic operations captured several towns, but the PAVN/VC military and political leadership narrowly escaped the cordon. The operation was partly a response to a PAVN offensive on March 29 against the Cambodian Army that captured large parts of eastern Cambodia in the wake of these operations. Allied military operations failed to eliminate many PAVN/VC troops or to capture their elusive headquarters, known as the Central Office for South Vietnam as they had left a month earlier, but the haul of captured materiel in Cambodia prompted claims of success.
Preliminaries
Background
The PAVN had been utilizing large sections of relatively unpopulated eastern Cambodia as sanctuaries into which they could withdraw from the struggle in South Vietnam to rest and reorganize without being attacked. These base areas were also utilized by the PAVN and VC to store weapons and other material that had been transported on a large scale into the region on the Sihanouk Trail. PAVN forces had begun moving through Cambodian territory as early as 1963.Cambodian neutrality had already been violated by South Vietnamese forces in pursuit of political-military factions opposed to the regime of Ngô Đình Diệm in the late 1950s and early 1960s. In 1966, Prince Norodom Sihanouk, ruler of Cambodia, convinced of eventual communist victory in Southeast Asia and fearful for the future of his rule, had concluded an agreement with the People's Republic of China which allowed the establishment of permanent communist bases on Cambodian soil and the use of the Cambodian port of Sihanoukville for resupply.
File:Mao Sihanouk.jpg|thumb|Meeting in Beijing in 1965: Mao Zedong, Prince Sihanouk, and Liu Shaoqi
During 1968, Cambodia's indigenous communist movement, labeled Khmer Rouge by Sihanouk, began an insurgency to overthrow the government. While they received very limited material help from the North Vietnamese at the time, they were able to shelter their forces in areas controlled by PAVN/VC troops.
The US government was aware of these activities in Cambodia, but refrained from taking overt military action within Cambodia in hopes of convincing the mercurial Sihanouk to alter his position. To accomplish this, President Lyndon B. Johnson authorized covert cross-border reconnaissance operations conducted by the secret Studies and Observations Group in order to gather intelligence on PAVN/VC activities in the border regions.
''Menu'', coup and North Vietnamese offensive
The new commander of the US Military Assistance Command, Vietnam, General Creighton W. Abrams, recommended to President Richard M. Nixon shortly after Nixon's inauguration that the Cambodian base areas be bombed by B-52 Stratofortress bombers. Nixon initially refused, but the breaking point came with the launching of PAVN's Tet 1969 Offensive in South Vietnam. Nixon, angered at what he perceived as a violation of the "agreement" with Hanoi after the cessation of the bombing of North Vietnam, authorized the covert air campaign. The first mission of Operation Menu was dispatched on March 18 and by the time it was completed 14 months later more than 3,000 sorties had been flown and 108,000 tons of bombs had been dropped on eastern Cambodia.While Sihanouk was abroad in France for a rest cure in January 1970, government-sponsored anti-Vietnamese demonstrations were held throughout Cambodia. Continued unrest spurred Prime Minister/Defense Minister Lon Nol to close the port of Sihanoukville to communist supplies and to issue an ultimatum on March 12 to the North Vietnamese to withdraw their forces from Cambodia within 72 hours. The prince, outraged that his "modus vivendi" with the communists had been disturbed, immediately arranged for a trip to Moscow and Beijing in an attempt to gain their agreement to apply pressure on Hanoi to restrain its forces in Cambodia.
National Security Advisor Henry Kissinger wrote in his memoirs that "historians rarely do justice to the psychological stress on a policy-maker", noting that by early 1970 President Nixon was feeling very much besieged and inclined to lash out against a world he was believed was plotting his downfall. Nixon had vowed to end the Vietnam War by November 1, 1969 and failed to do so while in the fall of 1969 he had seen two of his nominations to the Supreme Court rejected by the Senate. Nixon had taken the rejection of his nominations to the Supreme Court as personal humiliations, which he was constantly brooding over. In February 1970, the "secret war" in Laos was revealed, much to his displeasure.
Kissinger had denied in a press statement that any Americans had been killed fighting in Laos, only for it to emerge two days later that 27 Americans had been killed fighting in Laos. As a result, Nixon's public approval ratings fell by 11 points, causing him to refuse to see Kissinger for the next week. Nixon had hoped that when Kissinger secretly met Lê Đức Thọ in Paris in February 1970 that this might lead to a breakthrough in the negotiations and was disappointed that proved not to be so.
Nixon had become obsessed with the film Patton, a biographical portrayal of controversial General George S. Patton, Jr., which he kept watching over and over again, seeing how the film presented Patton as a solitary and misunderstood genius whom the world did not appreciate, a parallel to himself. Nixon told his chief of staff, H.R. Haldeman, that he and the rest of his staff should see Patton and be more like the subject of the film. Feeling that events were not working in his favor, Nixon sought some bold, audacious action that might turn his fortunes around.
In particular, Nixon believed that a spectacular military action that would prove "we are still serious about our commitment in Vietnam" might force the North Vietnamese to conclude the Paris peace talks in a manner satisfactory to American interests. In 1969, Nixon had pulled out 25,000 U.S. troops from South Vietnam and was planning to pull out 150,000 in the near future. The first withdrawal of 1969 had led to an increase in PAVN/VC activities in the Saigon area, and Abrams had warned Nixon that to pull out another 150,000 troops without eliminating the PAVN/VC bases over the border in Cambodia would create an untenable military situation. Even before the coup against Sihanouk, Nixon was inclined to invade Cambodia.
On March 18, the Cambodian National Assembly removed Sihanouk and named Lon Nol as provisional head of state. Sihanouk was in Moscow, having a discussion with the Soviet Premier Alexei Kosygin, who had to inform him mid-way in the conversation that he had just been deposed. In response, Sihanouk immediately established a government-in-exile in Beijing allying himself with North Vietnam, the Khmer Rouge, the VC and the Laotian Pathet Lao. In doing so, Sihanouk lent his name and popularity in the rural areas of Cambodia to a movement over which he had little control.
Sihanouk was revered by the Khmer peasantry as a god-like figure and his endorsement of the Khmer Rouge had immediate effects in rural areas. The reverence for the royal family was such that after the coup Lon Nol went to the Royal Palace, knelt at the feet of the queen mother Sisowath Kossamak and asked for her forgiveness for deposing her son. In the rural town of Kampong Cham, farmers enraged that their beloved ruler had been overthrown lynched one of Lon Nol's brothers, cut out his liver, cooked it and ate it to symbolize their contempt for the brother of the man who overthrew Sihanouk, who was viewed as the rightful once and future king.
Sihanouk was enraged by the vulgar media attacks by Lon Nol against himself and his family, saying in interview with Stanley Karnow in 1981 that despite the fact that the Khmer Rouge slaughtered much of the royal family including several of his children he still had no regrets about allying himself with the Khmer Rouge in 1970. His voice raising in fury, Sihanouk told Karnow: "I had to avenge myself against Lon Nol. He was my minister, my officer and he betrayed me". Sihanouk left Moscow for Beijing, where he was greeted warmly by Zhou Enlai, who assured him that China still recognized him as the legitimate leader of Cambodia, and would back his efforts at restoration.
Sihanouk went on Chinese radio to appeal to his people to overthrow Lon Nol, whom he depicted as a puppet of the Americans. Lon Nol was an intense Khmer nationalist, who detested the Vietnamese, the ancient archenemies of the Khmer nation. Like many other Khmer nationalists, Lon Nol had not forgotten the southern half of Vietnam was part of the Khmer empire until the 18th century nor had he forgiven the Vietnamese for conquering an area that historically was part of Cambodia.
Though Cambodia had a weak army, Lon Nol had given Hanoi 48 hours to pull its forces out of Cambodia and began the hasty training of 60,000 volunteers to fight the PAVN/VC. By late March 1970, Cambodia had descended into anarchy as Karnow noted: "Rival Cambodian gangs were hacking each other to pieces, in some instances celebrating their prowess by eating the hearts and livers of their victims."
The North Vietnamese response was swift; they began directly supplying large amounts of weapons and advisors to the Khmer Rouge and Cambodia plunged into civil war. Lon Nol saw Cambodia's population of 400,000 ethnic Vietnamese as possible hostages to prevent PAVN attacks and ordered their roundup and internment. Cambodian soldiers and civilians then unleashed a reign of terror, murdering thousands of Vietnamese civilians. Lon Nol encouraged pogroms against the Vietnamese minority and the Cambodian police took the lead in organizing the pogroms.
On 15 April for example, 800 Vietnamese men were rounded up at the village of Churi Changwar, tied together, executed, and their bodies dumped into the Mekong River. They then floated downstream into South Vietnam. Cambodia's actions were denounced by both the North and South Vietnamese governments. The massacres of Cambodia's Vietnamese minority greatly enraged people in both Vietnams. Even before the supply conduit through Sihanoukville was shut down, PAVN had begun expanding its logistical system from southeastern Laos into northeastern Cambodia.
Nixon was taken by surprise by the events in Cambodia, saying at a National Security Council meeting: "What the hell do those clowns do out there in Langley ?". The day after the coup, Nixon ordered Kissinger: "I want Helms to develop and implement a plan for maximum assistance to pro-U.S. elements in Cambodia". The CIA began to fly in arms for the Lon Nol regime, through the Secretary of State William P. Rogers told the media about Cambodia on March 23, 1970 "We don't anticipate that any request will be made". Realizing that he had lost control of the situation, Lon Nol did a volte-face and suddenly declared Cambodia's "strict neutrality".
On March 29, 1970 the PAVN launched an offensive against the Cambodian Khmer National Armed Forces, quickly seizing large portions of the eastern and northeastern parts of the country, isolating and besieging or overrunning a number of Cambodian cities including Kampong Cham. Documents uncovered from the Soviet archives revealed that the offensive was launched at the explicit request of the Khmer Rouge following negotiations with Nuon Chea. In early-April South Vietnamese Vice President Nguyễn Cao Kỳ twice visited Lon Nol in Phnom Penh for secret meetings to reestablish diplomatic relations between the two countries and agree on military cooperation. On April 14, 1970, Lon Nol appealed for help, saying that Cambodia was on the verge of losing its independence.
On April 17 the Khmer Republic announced that North Vietnam was invading Cambodia and appealed for assistance in countering North Vietnamese aggression. The U.S. responded immediately, delivering 6,000 captured AK-47 rifles to the FANK and transporting 3–4,000 ethnic Cambodian Civilian Irregular Defense Group program troops to Phnom Penh. On April 20 the PAVN overran Snuol, on April 23 they seized Memot, on April 24 they attacked Kep and on April 26 they began firing on shipping along the Mekong River, attacked Chhloung District northeast of Phnom Penh and captured Ang Tassom, northwest of Takéo. After defeating the FANK forces, the PAVN turned the newly won territories over to local insurgents. The Khmer Rouge also established "liberated" areas in the south and the southwestern parts of the country, where they operated independently of the North Vietnamese.