to the Khmer Rouge, which in the 1980s proved to be the most capable insurgent force, while the U.S. publicly supported a non-Communist alternative to the PRK; in 1985, the Reagan administration approved $5 million in aid to the republican KPNLF, led by former prime minister Son Sann, and the ANS, the armed wing of the pro-Sihanouk FUNCINPEC party. The KPNLF, while lacking in military strength compared to the Khmer Rouge, commanded a sizable civilian following (up to 250,000) amongst refugees near the Thai-Cambodian border that had fled the KR regime. Funcinpec had the benefit of traditional peasant Khmer loyalty to the crown and Sihanouk's widespread popularity in the countryside. In practice, the military strength of the non-KR groups within Cambodia was minimal, though their funding and civilian support was often greater than the KR. The Thatcher and Reagan administrations both supported the non-KR insurgents covertly, with weapons, and military advisors in the form of Green Berets and Special Air Service units, who taught sabotage techniques in camps just inside Thailand. The end of the CGDK and Khmer Rouge A UN-led peacekeeping mission that took place from 1991 to 1995 sought to end violence in the country and establish a democratic system of government through new elections. The 1990s saw a marked decline in insurgent activity, though the Khmer Rouge later renewed their attacks against the government. As Vietnam disengaged from direct involvement in Cambodia, the government was able to begin to split the KR movement by making peace offers to lower level officials. The Khmer Rouge was the only member of the CGDK to continue fighting following the reconciliation process. The other two political organizations that made up the CGDK alliance ended armed resistance and became a part of the political process that began with elections in 1993. In 1997, Pol Pot ordered the execution of his right-hand man Son Sen for attempting peace negotiations with the Cambodian government. In 1998, Pol Pot himself died, and other key KR leaders Khieu Samphan and Ieng Sary surrendered to the government of Hun Sen in exchange for immunity from prosecution, leaving Ta Mok as the sole commander of the Khmer Rouge forces; he was detained in 1999 for "crimes against humanity." The organization essentially ceased to exist. Recovery and trials Since 1990 Cambodia has gradually recovered, demographically and economically, from the Khmer Rouge regime, although the psychological scars affect many Cambodian