Opinion: March 18, 1970: ‘Revolutionary’ Group Moves Against Sihanouk

On the morning of March 18, 1970, the Australian Embassy in Saigon flashed a highly classified message to Canberra reporting that it had learned in Saigon that an assassination attempt against Prince Norodom Sihanouk was being planned and that “reports of planned assassinations were not unusual per se but more attention was being given to this particular one.”


Since the beginning of March 1970, Cambodia had been shaken by anti-Vietnamese demonstrations directed against the Viet Cong and North Vietnamese who had abused the facilities given by the Cambodian government on their territory.

The demonstrations had been organized by Lon Non, brother of General Lon Nol, commander in chief of the Royal Cambodian Army (RCA) and his close friend, Colonel Les Kossem, who had previously served as liaison officer of the RCA with the Communist Vietnamese for the delivery of arms and equipment sent by China and other Communist nations. In the process, Les Kossem and other military leaders had made a handsome fortune by siphoning off part of the arms and selling them on the black market, often to the same Communist Vietnamese.

Lon Non and Les Kossem had used recently rallied Khmer Serei forces to orchestrate the demonstrations that had ended with the sacking of the embassies of the Provisional Viet Cong and North Vietnam. The Khmer Serei, composed mostly by Khmers from Southern Vietnam, or Khmer Kampuchea Krom, formed part of the U.S. Army cover operations deep inside Cambodia with the help of the South Vietnamese Army.

The U.S. Army had a group known as Studies and Observation Group (SOG) and shared a base with South Vietnamese intelligence, in Long Hai, Tay Ninh province, known as SOG B-36, where they hosted Lon Nol several times prior to the 18 March 1970 Coup.

On March 15, information reached Queen Mother Sisowath Kossamak at the Royal Palace that events had reached a turn for the worse and that Lon Nol and those who wanted Sihanouk out of the political fray were prepared to assassinate him. Indeed, a tunnel had been excavated on the road to Pochentong Airport, where the airport road crosses the road to Stung Meanchey. A bomb was to be placed in the tunnel that would explode as the motorcade bringing Prince Sihanouk from the airport to the Royal Palace passed through.

At 11 p.m. that day, the Queen Mother summoned Um Sim, director of the Post/Telegraph service, and asked him: “Can we entrust you with a confidential task?” Um Sim replied without hesitation: “yes.” The Queen Mother then proceeded to dictate a message in Khmer to her son, warning him about the plot and advising against his return to Cambodia.

Um Sim transcribed the dictation in Roman characters and then read it back to her. After a minor correction, he took the message himself to his office and sent it himself to Moscow, where Prince Sihanouk was negotiating with his host the exit of Communist forces from Cambodia. Um Sim then brought back to the Queen Mother the original text and the punched tape of the telegram.

Lon Nol had been involved in the arrangements for the coup from the beginning but had delegated his brother, Lon Non, to be his representative in the so-called “Revolutionary Committee.” Lon Nol had agreed to accept the leadership of Cambodia if the group was successful but participated in none of the Committee’s activities.

From early 1960, the Cambodian head of state, Prince Sihanouk, had ruled Cambodia with the support of two main teams of trusted advisers: the “Economic/ Financial team” led by Samdech Penn Nouth and Samdech Son Sann and the “Defense and National Security team” led by Samdech Nhiek Tioulong and Lon Nol.

When Prince Sihanouk embarked on a program of economic reform in 1965, he relied on the Economic/Financial team, plus a few left-wing personalities such as Chau Seng and Hu Nim, to effect the reforms. This caused further resentment in the army.

In late 1968, Lon Non and Tep Kunnah, an influential businessman with many links to the financial and business community in Phnom Penh, decided to form a cohesive anti-Sihanouk movement. Thus, the Revolutionary Committee was born.

Their basic objection to Prince Sihanouk was that the Prince believed that a Communist victory in Southeast Asia was inevitable, and while he did not have a particular liking or tolerance for Communism, Sihanouk felt that Cambodia had to live with such eventuality and be good friends with a unified Communist Vietnam. The “Revolutionary Committee” felt that Prince Sihanouk “was compromising the future of Cambodia” by adopting a friendly attitude toward Communist Vietnam.

Membership of the Committee was kept to a minimum for security reasons. Lon Non, who had been a professional intelligence officer since 1954, served as Committee chairman and assured the clandestine aspects of the Committee’s activities. Other members were Les Kossem; Colonel Hou Hangsin, Phnom Penh’s Garrison Commander; Tep Kunnah, who provided financial guidance and support to the Committee as well as penetrating the Palace’s circles; Lieutenant Colonel Vong Sarendy, chief of the Cambodian Navy; Lieutenant Colonel Chhim Chhuon, chief of the Military Police, who was responsible for providing security for Committee members and was Les Kossem’s deputy for military planning (without his support the coup could not have succeeded); Lieutenant Colonel Lim Sisaath, who was in charge of the Cambodian Army’s ordnance and, therefore, assured that an adequate ordnance supply was available to loyal units the day of the coup; and lastly, Hang Thun Hak, minister for community development in the Lon Nol government, who organized the support of the students.

The Committee’s original intent was to gain control of the government by ensuring the election of persons who would take their lead from the Committee after becoming parliamentarians. They also wanted to place some restraints on Prince Sihanouk and to control him through their own manipulation of the National Assembly.

By October 1969, a majority of key Cambodian government officials had been contacted by the Committee and had agreed to support it. Seventy percent of the Council of Ministers was also cooperating and Prince Sihanouk’s Office had been infiltrated and thus, the Committee knew in advance all of Prince Sihanouk’s plans.

In January 1970, the Revolutionary Committee decided to implement its plans at the end of 1971 and even after the departure of Prince Sihanouk for France, the Committee continued to believe that it should delay final action to gain control of the government until the end of 1971.

However, the Committee took advantage of events and decided to organize the March 11, 1970 riots against the North Vietnamese and Viet Cong embassies in Phnom Penh. The date of March 11 was selected because on March 11, 1965 there were riots in Phnom Penh against U.S. government installations, sending a signal to the U.S. that they had friends within Cambodia.

The Committee also wanted to alert the Cambodian population to the danger to Cambodia that existed as a result of the Vietnamese Communists’ presence on Cambodian soil. Lastly, the Committee was attempting to force Prince Sihanouk to take a stand against the Vietnamese Communists’ continued presence in Cambodia.

However, the Committee’s fixation with the Vietnamese Communists’ presence on Cambodian soil was a mere excuse to overthrow the Prince, as the latter had made numerous complaints about North Vietnamese and Viet Cong encroachment on Cambodian territory, particularly between June 1969 and his deposition on March 18, 1970.

In June 1969, for instance, Prince Sihanouk had claimed that Ratanakkiri province was practically North Vietnamese territory and had noted the presence of Viet Minh (North Vietnamese) and Viet Cong troops inside Cambodia’s borders, particularly in Svay Rieng province.

But by March 16, 1970, most members of the Committee concluded that they should take advantage of the prevailing situation to depose the Prince and align Cambodia with the American effort against the Communists in Vietnam. This change of position was not fully understood, however, by some of the rioters and supporters of the Committee who continued to publicly state that they desired the return of the Prince to Cambodia as head of state.

When the Committee decided to move against the Prince, prior to the March 18 meeting of the National Assembly, their supporters in the Assembly moved for a closed session, in order to encourage members to speak in favor of the deposition of the head of state. It was the only way to ensure the success of the “legal” facade of the coup and the removal of Prince Sihanouk. At the same time, the National Assembly was surrounded by the tanks and armored vehicles of Phnom Penh’s garrison and deputies were warned that if they did not support the motion ousting the Prince as head of state, they would never see their families again.

The coup happened exactly a year after the departure from Cambodia of Australian Ambassador Noel Deschamps, who, as representative of the U.S. in Cambodia, from May 1965 until March 18, 1969, had worked hard to prevent such an occurrence because he knew well that if there was a coup against Prince Sihanouk, the unity of the country would be broken and Cambodia would be engulfed by the Vietnam War. In the end, he felt that Canberra had given him up due to pressure from Washington and that was why he was withdrawn from Cambodia and sent to a less-controversial post: Chile.

Julio Jeldres is the official biographer for the late King Father Norodom Sihanouk and a research fellow at the Monash Asia Institute at Monash University in Melbourne.

Disclaimer: The views and opinions expressed in this article are those of the author and do not necessarily reflect the views of The Cambodia Daily.

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