Any fears the world may have had of a united, communist Indochina toppling the pro-Western governments of Southeast Asia like dominoes have been laid to rest along the Vietnamese-Cambodian border.

A federation of Indochinese states - Vietnam, Cambodia and Laos - was the dream of the late Ho Chi Minh.

It was not to be.

Having turned the once-gentle land of Combodia upside down, the renegade communist leaders of Democratic Kampuchea are now engaged in a major war with the vastly superior Vietnamese army. There is no solution in sight. Nor is there likely to be a decisive conclusion.

Rather, in the view of some leading specialists, the fighting is likely to continue indefinitely. China, which is the only major nation with any degree of influence in Phnom Penh, has counseled caution. Similarly, the Soviet Union, which wields considerable power in Hanoi, has advised Vietnam to contain itself.

The Chinese don't want to see Cambodia dismembered, a not unlikely prospect given the disproportionate superiority of Vietnam's manpower and arms stockpile and three decades of combat experience in the jungle.

The Soviet Union is more concerned with not wanting Vietnam to appear to be an aggressor in the eyes of the world at a time when the Hanoi government has begun a major campaign to raise funds in non-communist capitals.

This aspect is only slightly less important to Peking. The Chinese and the Soviet Union both are pumping vast amounts of aid into war-devastated Vietnam, and would like to share the burden with as many other donors as possible.

What an extraordinary turn of events this border war between the Indochinese communists is! Who could have foreseen in April 1975, when the victorious jungle fighters rolled first into Phnom Penh and then into Saigon, that they would be killing each other today?

But so much of what has happened in Indochina, in Cambodia especially, could not have been foreseen.

Nobody in the West really understood the motivation, the commitment, the compulsions of those men and women from the jungles.

Now, it's become somewhat more clear. Those Cambodians who learned communism in Paris, then spent years nurturing their bitterness in the jungles, in Hanoi and Peking, had, by the time they reached Phnom Penh, formulated very definite ideas about what kind of country theirs should be.

Compact, homogeneous, fertile, inherently rich, it could become the most self-reliant state in Southeast Asia. So, immediately, the new rulers sealed Cambodia's borders as best they could.

Thousands did manage to spill across the frontiers in the first months after the war. The bulk fled to Thailand; others slipped into southern Vietnam. Infuriated by what they viewed as foreign complicity, the Cambodian communists lanched intese ground attacks on Thai border outposts and villages.

For awhile, before Phnom Penh and Hanoi announced a month ago that they had broken diplomatic relations, it appeared that the Cambodians hostility was directed almost exclusively against the capitalist Thais.

When Foreign Minister Ieng Sary made a speech before the United Nations and condemned those who coveted Cambodian territory and allowed foreign military bases on their soil, it seemed he was condemning Thailand.

It now appears that he was also attacking Vietnam and Laos, which has turned into nothing more or less than a protectorate of its vietnamese big brother.

Although sporadic border clashes still continue along the Thai frontier, they are not nearly as bloody or intense now. China, which wants to assert its influence among the non-communist states of Southeast Asia, has seen to that.

Why Cambodia and Thailand should squabble is perfectly understandable. Aside from the their total ideological differences, the Thais, according to Cambodia, have been funding and fueling whatever resistance has been organized against the Phnom Penh regime.

But why Cambodia and Vietnam should be at dagger points seems at least at first flance, puzzling. After all, they're both Indochinese, both former French colonies, allies, communists.

But this is modern history. Vietnamese and Cambodians have been enemies since emerging from the mists of time. Their ancient animosity is based on racial hatred and mutual claims of territorial encrochment.

When the xenophobic leaders of the new Cambodia felt themselves coming under pressure from Hanoi to suppress their burning ambition for total independence in favor of an alien dream of a unified Indochina, they went to war once again. And except for a reprieve in 1976, the fighting has gone to since mid-1975.

There is no clearcut aggressors, no obvious victim.Some might see Vietnam as the bully, an ironic surrogate for the United States. But even these observers would find it difficult to sympathize with the brutal Cambodian regime.

Yet for us in the West, in the United States especially, Indochina has become a minor curiosity, - a non-event.

Indochina, all of Southeast Asia, has already slipped into the tertiary position it held in U.S. foreign policy, before our first troops landed in South Vietnam.

Ambitious American diplomats and military officers no longer want to serve in the area. "It's all over," a young military attache said in Bangkok recently. "Anyone who wants to build his career has to get out of Southeast Asia now."

Southeast Asia is no longer news.

"Look," a State Department official said the other day, "we lost Indochina and so, naturally, we lost interest.

But many of those Americans who struggled most bitterly against U.S. involvement during all those bloody years now insist that United States make amends. This is in response to the "heal the wound of war" demands of the Vietnamese and the Laotians.

What about the property that was destroyed? They ask. The thousands that were maimed? The children that were orphaned. The women that were widowed. Doesn't the United States have a moral obiligation beyond politics? they ask.

Two of these people, Douglas Beane of the New York-based National Council of Churches and William Herod of the Disciples of Christ, stopped in Bangkok last year after visiting Saigon, now called Ho Chi Minh City, and Hanoi.

The economy in both parts of Vietnam was "quite difficult," the two men said, and economic decline or advance would directly influence the continuing flow of refugees.

"more people will stick it out. If they get worse, more will try to leave. That's natural."

Beane and Herod said that during their visit, they "tried to look at things through Vietnamese eyes as well as your own." From this perspective, they concluded that Hanoi regime's policy on religion in the south was "not repressvie."

Contrary to continuing reports that Christian and Buddhist leaders are being arrested, their churches and temples closed, they said all evidence they saw indicated that the regime and the church were trying to determine a "constructive role" for religious groups.

More recently, three other American church workers discussed their visit to the bomb-devastated Plain of Jars in Laos. They reported that while all Buddhist temples in the area had been destroyed by U.S. bombing, they saw "several" monks in saffron robes.

These observations suggest that communists are not simply wiping out organized religion and other characteristics of traditional life in Vietnam and Laos.

Cambodia, clearly is in a class by itself. So sweeping and so consistent have been the reports of brutality and repression from refugees and political escapees, as well as a handful of communist defectors, that no reasonable person can easily dismiss them. But things might, just might, be starting to change.

Prime Minister, Pol Pot recently made note of the "helpful" role of Prince Norodom Sihanouk during the five-year war. Sihanouk 57, a devout Buddhist and avowed anticommunist who had been treated by his subjects as a demigod, is understood to be a virtual captive in Phnom Penh.

The first public mention of his name by the mysterious Pol Pot would seem to suggest, however faintly, that the Cambodian communists are finally beginning to moderate their image, if not their performance within the hermit state.

This view is partially supported by the visit to Phnom Penh of Thailand's foreign minister and, before that, by the president of adamently neutralist Burma and the foreign minister of Malaysia, a prosperous, capitalist member of the non communist Association of Southeast Asian Nations.

The pressure of China on the Cambodians coupled with the pressure of war with Vietnam may yet force the Phnom Penh radicals to emerge from their shell.

There is already good reason to believe that the Cambodians, as well as the Vietnamese, would like to broaden their contacts with the non-communist world, if for no other reason than to temper the leverage brought to bear on them by China and the Soviet Union.

"Say what you like," commented an Asian diplomat in Bangkok not long ago, "but these people are trying to run their own countries. They fought like hell for all those years and they're not going to be happy about seeing the Americans replaced by the Russians and the Chinese."

Similarly, the noncommunists in the region, now that they realize fully that the United States has taken the Southeast Asian pot off the stove, are doing their best to build working relations with their neighbors. So far, it seems to be working.

Next: The noncommunists