Bangkok, Thailand — Southeast Asia and the long-troubled land of Kampuchea are facing new tests.
At stake is whether China, noncommunist Southeast Asia, the United States, and a just-concluded coalition of three Kampuchean nationalist forces can weaken Vietnam or even force it into retreat. The common goal goal is to prevent Vietnam from building an Indochinese empire based on occupation of Kampuchea.
The three Khmers who after 18 months of acrimonious negotiation have just formed a wobbly coalition government of ''Democratic Kampuchea'' have two things in common: opposition to the Vietnamese presence in Kampuchea and a profound dislike for one another.
The question is whether the common dislike of Vietnam shown by Prince Sihanouk, Son Sann, and the Khmer Rouge's Khieu Sampan will be enough to sustain a guerrilla war against Vietnam's military occupation of Kampuchea. Att stake is whether the new coalition will strengthen the United Nation's continued refusal to give Kampuchea's UN seat to the Vietnamese-backed government of Heng Samrin.
But experienced diplomats and journalists in the area harbor serious doubts on whether the coalition will hang together. Even if it survives on paper, it must prove that it is capable of effective cooperation in the military field.
The coalition's advocates, including China, the Association of Southeast Asian Nations (ASEAN), and, indirectly, the United States, hope that despite its weaknesses it will raise the price of Hanoi's efforts to dominate Kampuchea and Laos. The performance of the coalition will also be a political test for ASEAN. Its members (Thailand, Malaysia, the Philippines, Singapore, and Indonesia) played an important role in encouraging the partnership.
In the past ASEAN and the US said that it would only consider aiding the Khmer groups once they had to formed an alliance. In practise, however, Singapore and Malaysia have been giving Son Sann aid for some time now - perhaps to encourage him to compromise - and some of Singapore's aid has probably been in the form of weapons. China meanwhile has given small amounts of military aid to both Sihanouk and Son Sann. In the future, however, the noncommunists are likely to look to ASEAN, Japan, and the West for aid while the Khmer Rouge will continue to depend on Peking.
During a current tour of ASEAN capitals, Prince Sihanouk is gaining only mixed reactions. Indonesia, for example, has refused military aid for the new coalition.
The Khmers seem to view their coalition as a fighting alliance. But ASEAN declarations have stressed the need for a political solution.
In theory the new ''government'' will help convince Kampucheans and the world that there is, in fact, a broad-based Kampuchean opposition to Vietnam. The willingness of both Prince Sihanouk and Son Sann to work with the often-feared Chinese-backed Khmer Rouge is also hoped to strenghten the claim of the Khmer Rouge to continue to hold Kampuchea's UN seat.
Still the three factions make no secret of their contempt for one another. As an economics tutor, Sihanouk says, Son Sann was a bore; as a minister he was too conservative, pro-Western. Son Sann, on the other hand, clearly viewed the prince as unpredictable; today some of Son Sann's close associates make no effort to hide their near-hatred for the prince and what one person termed his ''frivolous'' decision to rally to the Khmer Rouge in 1970. That, they feel, contributed to the deaths of relatives and compatriots.
Both men agree, however, that the Khmer Rouge, whose titular leader is Khieu Samphan, another former Sihanouk minister, are mass murderers hated by the Khmer people.
When the three men finally joined forces in Kuala Lumpur, Malaysia, Prince Sihanouk found himself head of state for Democratic Kampuchea for the second time. His first term of office ended in house arrest after a year.
Khieu Samphan, whom the prince sometimes calls ''my jailer'' in less than fond remembrance of his days under house arrest, becomes vice-president of the coalition, and reportedly at Chinese insistence obtains the foreign affairs portfolio so vital to a government without territory of its own. Son Sann, who had held out for the foreign affairs spot, has to be satisfied with the premiership. The three form the coalition's inner cabinet.
Hammering out the coalition was a tense, painful affair. Aside from the inner cabinet, other portfolios are administered by troikas composed of a representative from each of the three factions. Given the government's lack of territory, most of the portfolios are of symbolic rather than real importance.
The political identities and even the armed forces of the three factions will remain separate. Perhaps most importantly each faction also retains the right to keep for itself any aid it might obtain.