Five Permanent members of the United Nations Security Council had a conversation in Paris in January 1990 and agreed that U.N. would control Cambodia and the Peace-Keeping Forces would be in charge of the security of Cambodia until the free election was carried out. It was August in the same year that the UN Security Council arranged measures to end the Cambodian civil war through the free general election. In accordance with the arrangement, The U.N. consisted the Supreme National Council in which 12 leaders including the Prime Minister Hun Sen supported by Vietnam and Sihanouk. Sihanouk became the chairman and Hun Sen the Vice-Chairman. Three Parties of the Coalition Cabinet agreed to the UN Plan but Hun Sen didn't, especially he strongly objected to Khmer Rouge's participating in the Coalition Cabinet.

Later, the 4 political parties were in the armistice state for the moment according as Supreme National Council resolved to make an indefinite armistice and not to receive any foreign assistance in Pattaya, Thailand, on June 24, 1991.

The Cambodian Civil War ended finally as four Cambodian political parties related to the Civil War and Minsters of Foreign Affairs from 19 countries attended Paris Conference as scheduled and signed Peace Pact.