The Khmer Rouge's links with China meant hostility between the Pol Pot government and Vietnam (soon to be briefly invaded by China for ill-treating Vietnam's ethnic Chinese). In 1978 Vietnam invaded Kampuchea and overthrew the Khmer Rouge. The guerrillas were driven into the western jungles and beyond to Thailand. Vietnam (now a communist republic forging links with the Soviet Union) set up a puppet government composed mainly of recent defectors from the Khmer Rouge. This new socialist government was comparatively benign, but found it hard to organise the necessary reconstruction programme: Pol Pot's policies had ruined the economy, there wasn't much foreign aid; all the competent professionals, engineers, technicians and planners had been killed.
The Khmer Rouge in retreat had some help from American relief agencies - 20,000 to 40,000 guerrillas who reached Thailand received food aid -and the West also ensured that the Khmer Rouge (rather than the Vietnam-backed communist government) held on to Cambodia's seat in the United Nations: the Cold War continued to dictate what allegiances and priorities were made.
The Khmer Rouge went on fighting the Vietnam-backed government. Throughout the 1980s the Khmer Rouge forces were covertly backed by America and the UK (who trained them in the use of landmines) because of their united hostility to communist Vietnam. The West's fuelling of the Khmer Rouge held up Cambodia's recovery for a decade.
Under international pressure, Vietnam finally withdrew its occupying army from Cambodia. This decision had also been forced by economic sanctions on Cambodia (the US's doing), and by a cut-off in aid from Vietnam's own backer, the Soviet Union. The last troops left Cambodia in 1989, and its name was officially restored. In the 1978-1989 conflict between the two countries (and their behind-the-scenes international string-pullers) up to 65,000 had been killed, 14,000 of whom were civilians.
In Cambodia, under a temporary coalition government, it was once again legal to own land. The state religion, Buddhism, was revived. In 1991 a peace agreement between opposing groups was signed. Democratic elections, and a peacekeeping force to monitor them, were arranged for 1993, and the former monarch, Prince Sihanouk, was elected to lead the new government.
The Khmer Rouge guerrillas, of course, opposed Cambodia's political reforms, but their organisation had begun to crumble. Many defected to the new government; many entered into deals to get immunity from prosecution. When Pol Pot accused one of his close aides of treachery, leading Khmers arrested him, and in 1997 staged a show trial. The government, meanwhile, made plans for a tribunal to bring former Khmer Rouge leaders to justice. Not surprisingly, those who have spoken publicly all lay the blame for genocide on Pol Pot, and claim no knowledge of the killing. They have also blamed people who are dead and can't argue, or accused 'enemy agents' from the American CIA, the Russian KGB, and Vietnam, all said to have organised the atrocity for obvious political reasons.
From 1995 mass graves began to be uncovered, revealing the genocide's horrifying extent. The resurrected bones and skulls have been preserved to create simple and potent memorials of the dead in 'the killing fields' where they died. At the torture centre in Phnom Penh, where the Khmer Rouge terrorised and murdered their own members, not only skulls but also identity photographs of the victims are displayed on the walls: this bleak, unhappy place has also become a memorial.
In 1998 Pol Pot died of natural causes. His last home in the jungle, a complex of huts and bunkers, which is also the site of his cremation, has become an attraction for visitors. The government has plans to create a fully equipped tourist resort there, in the hope of reviving a trade which had collapsed after the attacks on New York and Washington on September 11 2001.