"We killed two Viets this morning. They were taking a bath, and our soldiers climbed up over them and opened fire." With obvious satisfaction, a Khmer Rouge officer, with a .45 pistol on his hip, reenacted the scene, first sighting along an imaginary rifle, then mimicking the Vietnamese raising their hands in terror and being shot through the chest.

The officer, probably a company commander judging by the fine cut and cleanliness of his black uniform -- squatted beneath a tree several hundreds yards inside Thailand and gazed toward a grove just across the border where the din of small arms and grenades indicated that the Khmer Rouge were again in contact with their adversary.

It was about 1 p.m. With him were half a dozen young men cradling AK47 automatic rifles. They listened without emotion to the fusillade but let slip soft chuckles when two journalists who joined them showed nervousness at being close to the fighting.

"Hear that?" the officer asked as a hollow report carried to us from the right. "That's one of ours, firing 60mm mortar. Wait a moment, and you'll hear the shell hit." He gestured toward Cambodia. After 10 seconds, an explosion was heard.

A mile-long walk through an uninhabited area on the Thai side of the border -- as well as a brief crossing into Cambodia -- led to encounters with about 100 Khmer Rouge soldiers camped out beneath bushes or marching with full packs.

Most were heavily armed and, with tube-like cloth bags of rice draped over their shoulders, well fed. Those who stopped to chat seemed confident they could take on troops of the Vietnamese-supported Heng Samrin government, who two weeks ago moved against Khmer Rouge settlements strung along the Cambodian side of the border and prompted more than 60,000 people to flee into Thailand.

"The Viets are just there," said a yound soldier encountered in a grove where about 30 soldiers were camped. "They've run out of rice. This morning a helicopter landed to bring in food for them, but we've got them surrounded." He stooped down to draw a rough map in the mud.

Behind him was the short barrel of a 60mm mortar. As he talked, a patrol of five men, one carrying a grenade launcher, strode quickly by toward the border.

Military analysts in Bangkok estimate that the Khmer Rouge army of fill our Pol Pot, driven from Phnom Penh by Vietnamese forces in January, still has about 25,000 men and women under arms. No one expects a battlefield defeat of the Vietnamese, who are believed to have between 150,000 and 200,000 troops deployed in Cambodia.

But if the discipline, health and weaponry of the Khmer Rouge encountered on the walk are at all representative, Pol Pot's army is still potent, capable of inflicting heavey casualties on the Vietnamese in the dryseason fighting ahead.

Continued access to havens in Thailand would further sharpen the Khmer Rouge's bite. Thai officials maintain that when soldiers -- of whatever side -- flee into Thailand, they are disarmed and asked to return to Cambodia. However, at Ban Khlong Wah and at another Khmer Rouge refugee encampment in Thailand further south, there were areas with hundreds of armed Cambodians and no sign of Thai troops.

Just across the border into Cambodia is Ban Rai Kluay, a settlement typical of those that the Khmer Rouge evacuated at short notice when Heng Samrin troops pushed into the Phnom Malai hills two weeks ago. The village is composed of several hundred tiny thatch huts raised a foot or two off the ground. Built on land cleared from thick jungle, the village is strung along a meandering stream that separates the two countries.

Like towns the Khmer Rouge emptied with its program of massive relocation 1975, Ban Rai Kluay was full of signs of a hasty departure. Huts were strewn with discarded rags and ashes from burnt-out cooking fires. Broken oxearts lay unended. One hut contained an empty Chinese ammunition box, highly valued as a rice storage box or stool.

But the village was not completely deserted. A ragged man tended one of many vegetable patches scattered between houses. From a hut several young men gazed listlessly at us as we walked toward them, then smiled when we used our words of Cambodian, the greeting, "Soke Sabai ."

"The fighting made it too hard to live here," said one of them in Thai. The village had contained 5,800 people. But Angka , the organization, as the Khmer Rouge government is known gave the order to move when Heng Samrin troops entered the area.

It turned out the languid men in the hut were sick soldiers, assigned to the rear to recover. The huts farthest from the stream were used at night by militia members now out in the field, the speaker explained. The Vietnamese were about four miles away.

At another nearby town, about 30,000 refugees from Khmer Rouge zones were camped out last week in forestland and open ground near a huge rock-faced mountain. Most of them appeared to be civilians, wearing ragged clothes and suffering heavily from disease and malnutrition.

From the main body of the camp a rough trail snakes up a wooded hill toward the border, which Thai officers said was about four miles away. The trail levels off after half a mile. There, hundreds of Khmer Rouge soldiers and their families -- well supplied with rice and in better health than the civilians -- had spread out their belongings last week.

A surprisingly affable, Thai-speaking soldier named Wol said he was a farmer from Battambang Province. Wol, 32, said he had been a member of the Khmer Rouge Angka since 1970. His wife sat on a mat by a log holding their 4-month-old baby. "Moving around like this is a real problem when you've got a child this young," he said with a laugh.

Conversation turned to a comparison of watches. Wol wore an old and bulky Omega, which he took off for inspection. Other soldiers who had wandered over to listen pulled pu their sleeves to reveal similar possesions, apparently Phnom Penh booty distributed to loyal servants of the revolution. Collective property or not, one watch was offered for sale.

There was other small talk, with Wol sometimes translating for the others, who seemed interested in what their foreign visitors had to say. They asked questions about the foreigners' lives and explained some of the relationships in the camp.

It was talk that one would expect with a contented Thai villager, not someone who had lived through one of the most cataclysmic wars and social upheavals in recent times and who may have had a personal role in atrocities of the Khmer Rouge government.

What were Wol's plans for the future? He gave with seeming full sincerity, as if no other were conceivable, the standard answer one hears from Khmer Rouge soldiers and cadre: "When the Vietnamese withdraw, we'll go back."

Hadn't he ever thought of settling in a third country? His answer was immediate: "How can we think of going elsewhere when the Viets are in Cambodia? They kill babies." He gestured at his child. "And old people." And if the war did end, no one would want to leave a country with so much good farmland.

These statements were delivered in measured tones. Wol mater-of-factly said the Vietnamese had killed many members of his family. "I've got no brothers or sisters left. The wife and kid are my only family."

It is clear that many of those civilians would desert the soldiers if given the chance. Journalists repeatedly have been approached by people complaining of Khmer Rouge oppression and asking for help to escape. The Thai government recently began moving refugees to more permanent camps and many civilians are expected to take the opportunity to apply for resettlement in the United States or other countries.

But up on the hill the sentiment is different. It is hard to understand how a cause that has brought year after year of unspeakable hardship could breed inflexible loyalty, but it seems clearly to have done that in Wol and many soldiers like him. People like them assure the Vietnamese face an enormous task in stamping out the Khmer Rouge movement.