After the Khmer Rouge regime was overthrown, a new Cambodian government supported by Vietnam, the People's Republic of Kampuchea (PRK), was established.
The Chinese leader, Deng Xiaoping, was unhappy with Vietnam's influence over the PRK government.
Deng proposed to Sihanouk that he co-operate with the Khmer Rouge to overthrow the PRK government, but the latter rejected it, as he opposed the genocidal policies pursued by the Khmer Rouge while they were in power.
In March 1981, Sihanouk established a resistance movement, FUNCINPEC which was complemented by a small resistance army known as Armée Nationale Sihanoukiste (ANS).
He appointed In Tam, who had briefly served as Prime Minister in the Khmer Republic, as the commander-in-chief of ANS.
The ANS needed military aid from China, and Deng seized the opportunity to sway Sihanouk into collaborating with the Khmer Rouge.
Sihanouk reluctantly agreed, and started talks in March 1981 with the Khmer Rouge and the Son Sann-led Khmer People's National Liberation Front (KPNLF) on a unified anti-PRK resistance movement.

After several rounds of negotiations mediated by Deng and Singapore's prime minister Lee Kuan Yew, FUNCINPEC, KPNLF, and the Khmer Rouge agreed to form the Coalition Government of Democratic Kampuchea (CGDK) in June 1982.
The CGDK was headed by Sihanouk, and functioned as a government-in-exile.
The UN defeated a resolution to expel Democratic Kampuchea and admit the PRK, effectively confirming Sihanouk as Cambodia's internationally recognized head of state.

As CGDK chairperson, Sihanouk unsuccessfully negotiated, over the next five years, with the Chinese government to broker a political settlement to end the Vietnamese occupation of Cambodia.
During this period, Sihanouk appointed two of his sons, Norodom Chakrapong and Norodom Ranariddh, to lead the ANS.
Chakrapong was appointed as the deputy chief-of-staff for the ANS in March 1985, while Ranariddh was minted to the twin positions of commander-in-chief and the chief-of-staff of the ANS in January 1986, replacing Tam.
In December 1987, the Prime Minister of the PRK government, Hun Sen, first met with Sihanouk to discuss ending the protracted Cambodian–Vietnamese War.
The following July, the then-foreign minister of Indonesia, Ali Alatas, brokered the first round of meetings between the four warring Cambodian factions consisting of FUNCINPEC, Khmer Rouge, KPNLF, and the PRK government over the future of Cambodia.
Two more rounds of meetings were held in February and May 1989; since all were held near Jakarta, they became known as the Jakarta Informal Meetings (JIM).

In July 1989, Ali Alatas joined French foreign minister Roland Dumas in opening the Paris Peace Conference, where discussions took place regarding plans for Vietnamese troop withdrawal and power-sharing arrangements in a hypothetical future Cambodian government.
The following month, Sihanouk resigned as president of FUNCINPEC but remained in the party as an ordinary member.
In September 1990, the United Nations (UN) sponsored the establishment of the Supreme National Council of Cambodia (SNC), an administrative body responsible for overseeing the sovereign affairs of Cambodia for an interim period until UN-sponsored elections were held.
The creation of the SNC was subsequently ratified with United Nations Security Council Resolution 668.
In July 1991 Sihanouk left FUNCINPEC altogether and was elected as the chairperson of the SNC.
After the Khmer Rouge regime was overthrown, a new Cambodian government supported by Vietnam, the People's Republic of Kampuchea (PRK), was established. The Chinese leader, Deng Xiaoping, was unhappy with Vietnam's influence over the PRK government. Deng proposed to Sihanouk that he co-operate with the Khmer Rouge to overthrow the PRK government, but the latter rejected it, as he opposed the genocidal policies pursued by the Khmer Rouge while they were in power. In March 1981, Sihanouk established a resistance movement, FUNCINPEC which was complemented by a small resistance army known as Armée Nationale Sihanoukiste (ANS). He appointed In Tam, who had briefly served as Prime Minister in the Khmer Republic, as the commander-in-chief of ANS. The ANS needed military aid from China, and Deng seized the opportunity to sway Sihanouk into collaborating with the Khmer Rouge. Sihanouk reluctantly agreed, and started talks in March 1981 with the Khmer Rouge and the Son Sann-led Khmer People's National Liberation Front (KPNLF) on a unified anti-PRK resistance movement.
After several rounds of negotiations mediated by Deng and Singapore's prime minister Lee Kuan Yew, FUNCINPEC, KPNLF, and the Khmer Rouge agreed to form the Coalition Government of Democratic Kampuchea (CGDK) in June 1982. The CGDK was headed by Sihanouk, and functioned as a government-in-exile. The UN defeated a resolution to expel Democratic Kampuchea and admit the PRK, effectively confirming Sihanouk as Cambodia's internationally recognized head of state.
As CGDK chairperson, Sihanouk unsuccessfully negotiated, over the next five years, with the Chinese government to broker a political settlement to end the Vietnamese occupation of Cambodia. During this period, Sihanouk appointed two of his sons, Norodom Chakrapong and Norodom Ranariddh, to lead the ANS. Chakrapong was appointed as the deputy chief-of-staff for the ANS in March 1985, while Ranariddh was minted to the twin positions of commander-in-chief and the chief-of-staff of the ANS in January 1986, replacing Tam. In December 1987, the Prime Minister of the PRK government, Hun Sen, first met with Sihanouk to discuss ending the protracted Cambodian–Vietnamese War. The following July, the then-foreign minister of Indonesia, Ali Alatas, brokered the first round of meetings between the four warring Cambodian factions consisting of FUNCINPEC, Khmer Rouge, KPNLF, and the PRK government over the future of Cambodia. Two more rounds of meetings were held in February and May 1989; since all were held near Jakarta, they became known as the Jakarta Informal Meetings (JIM).
In July 1989, Ali Alatas joined French foreign minister Roland Dumas in opening the Paris Peace Conference, where discussions took place regarding plans for Vietnamese troop withdrawal and power-sharing arrangements in a hypothetical future Cambodian government. The following month, Sihanouk resigned as president of FUNCINPEC but remained in the party as an ordinary member. In September 1990, the United Nations (UN) sponsored the establishment of the Supreme National Council of Cambodia (SNC), an administrative body responsible for overseeing the sovereign affairs of Cambodia for an interim period until UN-sponsored elections were held. The creation of the SNC was subsequently ratified with United Nations Security Council Resolution 668. In July 1991 Sihanouk left FUNCINPEC altogether and was elected as the chairperson of the SNC.
Norodom Sihanouk