DESPITE breakthroughs in ending their 12-year civil war, Cambodia's warring leaders remain divided over how to make peace work.Last week in this Thai resort, the Phnom Penh regime and three resistance factions moved steadily toward a final peace settlement. An overall peace accord is predicted by the end of the year, say diplomats from the five permanent members of the United Nations Security Council which must approve a deal. Still, the compromises made at the talks have raised new conundrums, underscoring the complexities and deep divisions in ending Cambodia's ordeal. "After 12 years of war, all the wounds are not yet healed," says Prince Norodom Sihanouk, the country's hereditary monarch who now heads the interim Supreme National Council (SNC). The keystone agreement was a plan to demobilize 70 percent of Cambodia's armed troops. Yet, what will happen to the remaining 30 percent is an issue between the Cambodians and the five UN powers which gave a tentative go-ahead to the plan. The Cambodians left for the UN Security Council the unresolved issue of what to do with Phnom Penh's elite A-3 secret police, which have not been included in current demobilization plans. The Cambodian factions also jockeyed over election plans, opting for a multiparty system but failing to settle on how the poll would be conducted. Phnom Penh Prime Minister Hun Sen, whose government controls the majority of the towns and countryside, wants a Westminster-style system in which a single representative from a constituency is elected by a simple majority. The guerrilla factions, however, want a system of proportional representation under which voters choose their representatives through a party list of candidates. The factions will meet again in New York this month when the compromise council assumes Cambodia's seat at the United Nations in New York. "Hun Sen and Phnom Penh will have to do serious thinking about this," suggested a diplomat from the Soviet Union whose aid to Phnom Penh and its patron, Vietnam, fell off last year. Support for the Cambodian peace agreement by the UN Security Council masks doubts over whether the Cambodians can keep a fragile peace intact. The five permanent members, including the United States, Britain, China, the Soviet Union, and France, drew up a peace framework calling for a massive UN role to oversee Cambodia's administration during a transition period and to monitor a cease-fire, demobilization, and elections. The US grudgingly accepted compromises to the UN plan, backing off from its hard stance after Prince Sihanouk repeatedly charged that US officials were obstructing the peace process. A senior US official says the United States still wants to see total demobilization to ensure a free and fair election, saying that "we want to avoid the danger of Cambodia becoming a Lebanon after the elections." The US, which is believed to have instigated a coup to overthrow Sihanouk in 1970 and is accused of triggering 20 years of turmoil in Cambodia, also is uneasy about a decision to give the former monarch final say in any impasse between the interim council and the UN. "The US is hanging very tough and is acting holier than the pope on this," says a diplomat from another Security Council country at odds with the US. The Cambodian leaders have begun positioning themselves for an upcoming election. Prince Norodom Ranariddh, Sihanouk's son and leader of the former monarch's resistance faction, said the chance of a deal brokered by China and Vietnam outside the UN ambit has receded with rapprochement among the Cambodians as well as between the two regional rivals. Under this so-called "red solution," the Phnom Penh communists, backed by Vietnam, and the Khmer Rouge, radical Marxists supported by China, would dominate a future government, likely to be headed by Sihanouk. Khmer Rouge officials say they will take a wait-and-see attitude and not run their own candidates but back other parties. "For the time being at least, the Vietnam-China rapprochement has produced a good compromise rather than a red solution," Prince Ranariddh said. "But I'm afraid for the future if the noncommunists remain as political forces as weak as they are today," he continued. "It would be a problem if [the Khmer Rouge and Phnom Penh] got a majority in the future national assembly. Predicting that factional infighting and lack of support from Vietnam will split the Phnom Penh regime, the Sihanouk forces are trying to support the liberal Hun Sen against hard-liners in the Cambodian capital who resist compromise. "I think we have an interest in maintaining Hun Sen as prime minister because if one day he is toppled, you will have to replace him with hard-liners within the SNC," Sihanouk said in a radio interview.