A FEW weeks ago, in a little village in the contested Cambodian province of Kompong Thom, I watched United Nations officials try to explain democracy to bemused villagers. It was moving. Now those villagers are in a war zone. Under the trees on the river bank, with the help of a television, a video, a loudspeaker and copies of ballot papers showing the symbols of the 20-odd parties that have registered in the election, UN officials repeated that villagers had to put a mark against just one party, whichever one they wished. Again and again they emphasised: your vote will be secret. Their message must be hard for ordinary people to believe. No such thing as a secret ballot or an election to transfer power has happened in Cambodia. Bullets, not ballots, have usually established or maintained power. Today Cambodians are due to vote in what was to have been the first free election in this beautiful but benighted country. In many places they will have to brave gunfire, grenade and mortar attacks to do so. The election was to have been the climax of the largest and most expensive UN peace-keeping effort undertaken. Its purpose was to bring Cambodia out of the cold and back into the international community. That entire effort is being threatened by merciless Khmer Rouge attacks on the entire peace-keeping process - and by the brutality of the Phnom Penh Government. Cambodia's central dilemma is that it is a small nation between two giants: nine million Cambodians are overshadowed to the west by 60 million Thais and to the east by 70 million overcrowded Vietnamese. When the Khmer Rouge was in power from 1975-78, it probably caused the deaths of more than a million of its own people. At first Hanoi dismissed as propaganda the horror stories refugees took to Thailand, but then the Khmer Rouge attacked across the Vietnamese border, and at the end of 1978 Vietnam invaded. For Cambodians, Vietnam's arrival was a liberation from the tyranny of the Khmer Rouge. But to the dismay of many, that liberation fast became an occupation. The Vietnamese installed a Marxist government made up in large part of Khmer Rouge defectors, and declared that it was all ''irreversible''. China, the United States and other Asian countries - and a majority of the UN - found Vietnam's conduct unacceptable. They built up opposition to the Vietnam regime, in the form of the Khmer Rouge and two non-communist groups, one led by Prince Norodom Ranariddh, the son of former Cambodian ruler Prince Norodom Sihanouk, and the other by former prime minister Mr Son Sann. A coalition of these three kept Cambodia's seat at the UN throughout the 1980s. For a long time Hanoi remained intransigent. Its regime in Phnom Penh, led by Mr Hun Sen (an effective prime minister), was less brutal than the Khmer Rouge, but it was dogmatic, corrupt, cruel and tainted by its association with Hanoi. For 10 years Vietnam resisted the rest of the world, but with the rise of Soviet leader Mr Mikhail Gorbachev, Hanoi lost Soviet support and in 1989 withdrew its troops. At last a settlement became possible. In October 1991, after an enormous international effort, the Cambodian peace agreement was signed in Paris. This provided that the UN would administer Cambodia until elections for a constituent assembly. All sides were to disarm. The four factions - the government, the Khmer Rouge, the Sihanoukists and the Son Sann group, and the Khmer People's National Liberation Front - were all to be on a Supreme National Council chaired by Prince Sihanouk. Until the election produced a new government, the SNC would embody Cambodia's sovereignty. The UN Transitional Authority in Cambodia has had some notable successes: it repatriated the 350,000 refugees who had fled to the Thai border; and registered about 95 per cent of the eligible voters to whom it had access. But, as always in Cambodia, political brutality towers over everything. Six months ago, the favourite to win the election was FUNCINPEC, the main opposition party, which is led by Prince Ranariddh. Its popularity is based on both its anti-communism andits royal status. The government declared war on it; at least 100 FUNCINPEC officials have been murdered or wounded by government agents. The Khmer Rouge has been playing to Cambodians' hatred of the Vietnamese, and has murdered innocent Vietnamese residents. The core of its ideology is still a fanatical, murderous nationalism. Polling is forbidden at this stage of the elections, but many UN officials believe Mr Hun Sen's party may win, through violence and intimidation. The position of Prince Sihanouk is both crucial and unpredictable. Although chairman of the SNC, he has spent much of recent months in China. Assuming the election is completed, in what UNTAC officials call ''minimally reasonable'' conditions, then in the three months the new constituent assembly has to create a constitution and appoint a government, the Khmer Rouge will try to maximise chaos.They will try to push Prince Sihanouk to come back and take power, and to construct a government of national reconciliation that includes them. If Prince Sihanouk rejects the results, he could provoke a widened civil war, as happened after 1970 when he was overthrown in a right-wing coup. Alternatively, he could do his country the greatest service of his long leadership and help build a more representative and honourable government than Cambodia has known. The overriding question will be what to do with the Khmer Rouge. Prince Sihanouk, Prince Ranariddh and other non-communist politicians in Phnom Penh argue that some of them should be included in the new government. These people are seeking reconciliation, not further war. But in my view the Khmer Rouge's present behaviour shows that reconciliation with it is a contradiction in terms. It must be defeated. What the Khmer Rouge fears most is that the election will produce an effective coalition between the best of the Hun Sen regime and FUNCINPEC. Such a government would get international support and its army would at once be built up by perhaps France or Australia. It could withstand the Khmer Rouge. Khmer Rouge members are not goliaths. They are ruthless and terrifying but they are thought to have only about 10,000 troops. They have not been able to take, let alone hold, any major target. They control only about 10 per cent of the population. Abroad they have lost the support of China. The only external support they have (and it is important) is from the corrupt Thai generals who enable them to sell Cambodian timber and gems through Thailand. After the election, unless they decide to compromise and unless Prince Sihanouk brings them back, they will be outlaws. Their only support will come from their Thai friends. They could, over years, be defeated. No wonder the Khmer Rouge feels there is an international conspiracy against it. There is. But its eventual defeat depends on the political behaviour as well as the military might of any new government. Ninety per cent of Cambodians are subsistent farmers: the average annual income is less than US$200 (HK$1,560). The new government must wage war on corruption and use the wealth that will come into the country for the benefit of all - not just the urban elite. That, alas, is a revolutionary thought for all Phnom Penh politicians. Enlightened political and social policies by a new government would have to be allied to a tough military policy designed to push the Khmer Rouge back to the borders where bandits have always flourished. It can be done. Its threat can be contained. The question is whether Phnom Penh's politicians have the will and the wisdom to do it. William Shawcross is the author of Sideshow and The Quality of Mercy, both about Cambodia.