As our strange convoy, a white Mercedes sedan sandwiched between two jeeploads of soliders, bumped along Route 7 headed for the Vietnamese border, I remembered what I had been told before leaving Washington.

U.S. analysts attempting to figure what was really happening in the current was between Vietnam and Cambodia had suggested that I ask Cambodian officials to take me back to Krek, Snoul or Mimot-three towns near the Vietnamese border.

"They won't take you there," one official had asserted. "The whole area is in the hands of the Vietnamese."

While the analysts may be correct that some border areas of Cambodia are under Vietnamese control. I can report conclusively that Krek was not in Vietnamese hands at the time of our visit.

My request that we be permitted to visit the other border towns was declined on grounds that the road was within range of Vietnamese artillery and the trip was "too dangeous."

But here we were on a bright December morning on our way from Kompong Cham, an old provincial city on the Mekong River, to Krek.

As we drove past farmers harvesting in fields of ripening rice, the only guns to be seem were the automatic weapons of our escort.

I told Pin, the Cambodian commader who was our guide that morning how Western experts felt that Vietnamese forces were in control of much of this area.

"I know what they think," he said with a smile. "A friend told me he heard over the radio that the Vietnamese hold positions in Kompong Cham city."

When we arriced at the village of Suong, our convoy stopped at an official government house where the three of us-British scholar Malcolm Caldwell, Richard Dudman of the St. Louis Post-Dispatch and I-were given a military briefing.

Pin laid out a map of the region on the table, and told us that Vietnamese forces had overrun a large part of this area a year ago. "The Viet namese killed 200 or 300 and kidnapped 300 or 400," Pin said.

Cambodian forces ultimately drove the Vietnamese troops back following that offensive, he said, and beat back a second Vietnamese attack during the summer.

Now, Pin said, the Vietnamese were trying again. He claimed that this time Vietnamese warplanes had bombed three border willages. But the fround fighting this time was lighter, he said.

"They launch an attack, we concentrate on their flanks, kill a few of them, and they go back," he declared.

Following the briefing, we resumed the journey to Krek. As we neared the border town, I could hear for the first time the thump of artillery and the sound of a jet flying overhead.

"Enemy," Pin declared.

We got our of the car in Krek, and soliders fanned out in all directions to provide protection. But there was no sign of the three Vietnamese Army divisions Pin said were massed across the border, just over a mile away.

The only indication that the Vietnamese army might be near was an occasional puff of smoke in a distant field, which Pin claimed was caused by incoming Vietnamese artillery shells.

Our visit to Krek-the closest I got to the front during my two-week journey-illustrates the difficulty the world has had in following this strang war between two former allies.

Western military analysts have found it almost impossible to evaluate the conflicting claims of invasion and counterinvasion emanting from Hanoi and Phnom Penh.

Unlike during America's Indochinese war, there are no Western reporters keeping track of the ebb and flow of this war from either side of the border.

We were, in fact, the first non-communist Western reporters allowed in Cambodian-Democratic Kampuchea, as it is noe spelled here-since the outbreak of the current fighting in December 1977.

Beyond the problem of figuring out what is actually going on, most Americans find it equally hard to understand the basis of the current fighting.

But the Communist rulers of Cambodia and Vietnam now greely admit that they were wary allies even as they both sought to topple the U.,S. backed governments of in Saigon and Phnom Penh.

Each country recently has published reports describing how the Khmer Rouge and Vietcong forces fought each other as they both battled the United States.

That war was barely over, Phnom Penh further charges, when Vietnam began trying to turn Cambodia into another client state like Laos as part of an effort to link all Indochinese states in a federation controlled from Hanoi.

"Vietnam has the ambition to swallow Kampuchea," Prime Minister Pol Pot said in an interview. "Vietnam wants to take Kampuchea as part of its Indochina federation scheme."

Western concern over the war between Vietnam and Cambodia also focused on the fact that each of the countries is backed by one of the Communist superpowers.

Canbodia has charged that Vietnam, which only a month ago signed a 25-year friendship treaty with the Soviet Union, has become the "Cuba of Southeast Asia"-a stalking horse for extending Soviet influence.

"If we were to become a satellite of Vietnam, it would be a danger to Southeast Asia and the world, because Vietnam is a Soviet puppet and carrying out the strtegy of Soviet international expansionism," Pol Pot told me.

The feat of falling under Vietnamese domination clearly weighs heavily on Cambodia's leaders. Pol Pot turned our entire 90-minute interview into a nonstop polemic against Vietnam, and later submitted written answers to my other questions.

But in its battle to remain independent, Cambodia relies heavily for military support on China.

On the road one day to Kompong Som, Cambodia's only deep-water seaport, we passed dozens of new Chinese-made military trucks. When we reached the harbour, we found a Chinese freighter tied up at the dock.

Cambodia obtains all the weapons and ammunition it is using in its war with Vietnam from Peking, but the leaders in Phnom Penh flatly refuse to talk about the amount or source of any military aid.

"We accept all unconditional foreign aid which is useful for our task of defending our national independence, sovereignty and territorial integrity," Pol Pot said in a written answer to one of my question.

While my two-week journey does not enable me to provide a definitive report on the military situation throughout Cambodia, I was given a remarkable new document in which Cambodia confirms for the first time the extent to which the Vietcong used the country for sanctuary during the early 1970s.

The 94-page "Black Paper," which bitterly details instances of Vietnamese aggression and perfidy dating back to 1471, reports that "in 1970, the figure of Vietcong in Kampuchea reached 1.5 million to 2 million."

The "Black Paper" also discloses that when former president Richard Nixon ordered the invasion of Cambodia in 1970, there were in fact some 200,000 to 300,000 Vietcong in the northeastern region of Cambodia including "the Central Committee of the Vietnamese Party-the long sought COSVN.

"In fact, the Vietcong had no territory in South Vietnam," a high-ranking official told me one night. "They has to come here. We had to provide them with food, hospital care, transportation for their military. At that time, there were 80,000 wounded VC in our hospitals."

When I asked why Cambodia had never disclosed this information-which closely paralleled U.S. intelligence estimates at the time-he remarked:

"Because we wanted to be in solidarity with Vietnam. In life, we can choose many things but we cannot choose our neighbors."

Today, Cambodian make it plain their chief concern is whether their large neighbor will let them continue to live as an independent state.