In October 1991, Cambodia's four warring factions signed the Paris Peace Accords, agreeing to end more than two decades of civil war and international isolation. The agreement assigned the United Nations an unprecedented role. For the first time in history, the UN would directly administer an independent country's government while preparing it for democratic elections.
The United Nations Transitional Authority in Cambodia (UNTAC) began operations in March 1992. At its peak, the mission deployed over 22,000 military and civilian personnel from 46 countries, making it the largest UN peacekeeping operation ever mounted at that time. UNTAC took direct control of five key Cambodian ministries and supervised all aspects of the transition, from demobilizing armed forces to organizing elections. The entire operation cost $1.6 billion.
In May 1993, Cambodians turned out in extraordinary numbers to vote. Despite Khmer Rouge attacks and intimidation campaigns, nearly 90 percent of registered voters participated in elections that UN observers declared free and fair. Prince Norodom Ranariddh's royalist party FUNCINPEC won the most votes with 45.47 percent, securing 58 seats in the National Assembly, while Hun Sen's Cambodian People's Party received 38.23 percent and 51 seats.
The CPP rejected the results. Rather than accept electoral defeat, Hun Sen and his supporters used threats of renewed violence to force their way into a power-sharing arrangement. The compromise created an unusual government with two prime ministers: Ranariddh as First Prime Minister and Hun Sen as Second Prime Minister. In September 1993, Cambodia adopted a new constitution establishing a constitutional monarchy with King Norodom Sihanouk as head of state. UNTAC withdrew, and Cambodia regained full sovereignty.
The coalition government proved unstable from the start. The CPP controlled most of the security forces and refused to share power at district and local levels. Opposition politicians faced harassment, detention, and assassination. By 1996, UN human rights monitors warned of a troubling return to authoritarian practices.
On July 5-6, 1997, fighting erupted in Phnom Penh. Hun Sen's forces used heavy weapons in urban areas to defeat FUNCINPEC troops, forcing Prince Ranariddh to flee the country. The coup violated Cambodia's constitution and overturned the results of the UN-sponsored election. Cambodia's brief democratic opening had ended. The pattern established in 1997 would shape Cambodian politics for decades to come, as Hun Sen consolidated single-party control over the country.