Bangkok — The thre anti-Veitnamese Cambodian groups holding secret unity talks here are reluctant to admit it publicly, but they seem to be getting nowhere fast. The United States, the five-nation Association of Southeast Asian Nation (ASEAN), and, to a lesser degree, China, have all supported the idea of a united front to drive the Vietnamese out of Cambodia.
But, were it not for their prodding, the talks, whch have gone on for several weeks, might have been disbanded by now.
The main problem remains a profound lack of trust among the three groups.
The two weakest -- both noncommunitst -- fear that the well-armed Khmer Rouge , which has renounced its history of brutality and murder, would dominate any coalition of forces.
Western diplomats believe the Chinese-supplied Khmer Rouge have as many as 35 ,000 men, many of them with combat experience, under arms. While far from capable of driving the Vietnamese out of Cambodia, the Khmer Rouge have improved their leadership, organization, and communications over the past year.
In contrast, the contrast, the forces of the Khmer People's National Liberation Front (KPNLF) under former Premier Son Sann are believed to have only 3,000 to 5,000 soldiers, although one estimate now gives them 7,000.At any rate they are more lightly armed than the Khmer Rouge and have had much less combat experience.
The forces of yet a third faction, led by exiled Prince Norodom Sihanouk, are smaller still.
The Khmer Rouge, said a Western diplomat, "hold all the chips."
The Khmer Rouge are in no hurry to compromise, said an Asian observer, especially now that they feel they are growing stronger and have retained their seat at the United Nations for yet another year.
"The Khmer Rouge don't want to work with us," said a Son Sann follower in Bangkok. "They want to swallow us."
To make themselves more acceptable, the Khmer Rouge have proclaimed a seemingly moderate political program. According to a study by Steven Heder of Cornell University, who has interviewed hundreds of Cambodians along the Thai-Cambodian border, the Khmer Rouge have also significantly reduced their use of violence against the Cambodian people.
Son Sann has likened the forming of a coalition with the Khmer Rouge to the lashing together of an ox with a tiger: The tiger is bound to destroy the ox.
"The Khmer Rouge now say that they are not interested in building socialism or communism," A Sihanouk follower said. "But the communists never respect any international agreement. . . . When you enter an agreement with the communists, you lose every time."
A number of the negotiators from the Son Sann and Sihanouk factions now sitting down with the Khmer Rouge in Bangkok had relatives who were killed by the Khmer Rouge during their four-year reign of terror over Cambodia.
Sources say that the Bangkok negotiators are extremely polite to each other. But one gets the impression that they stay with the negotiations only because their powerful backers want it that way.
"We want to shoe the countries of ASEAN that we are not the stubborn ones," said a spokesman for the Son Sann group.
However, Son Sann is reported to have demanded at one point that the KPNLF be given most of the cabinet positions in any coalition government. He also has been asking for US and Chinese military aid.
China has supplied him with a relatively small number of arms. Thailand is also believed to have delivered a limited number of light infantry weapons to Son Sann forces.
A member of the Sihanouk group said that the three Cambodian factions are now arguing over political principles. They have apparently disagreed as well over how power would be divided and over who would control supplies.
The Sihanouk and Son Sann factions have argued with each other over questions of leadership. The Son Sann group accuses Prince Sihanouk of failing to stick with a promise of support for Son Sann. The Sihanouk group denies that this is the case.
Despite the obvious disunity of the unity talks. Western nations have continued to express support for the effort. In Peking on Oct. 8, West Germany's Foreign Minister Hans-Dietrich Genscher told China's Foreign Minister Huang Hua that Germany hopes a Cambodian united front will provide a democratic alternative to end foreign intervention in that Southeast Asian nation.