The small town of Cuamato lies about 25 miles north of the Namibian border, set in the typical countryside of this almost invisible war -- a dense covering of scrubby trees, mostly little more than the height of a man but thick enough to provide good cover.

In the rainy season, which lasts, until April, a light sprinkling of grass emerges on the sandy soil. Cattle graze among the trees and in the occasionl clearings marsh birds pick their way delicately across temporary pools and swamps which the sun, even in the heat of the day, never quite manage to dry out.

In the late afternoon one day last month, the whir of rotor blades burst in on a settlement just west of Cuamato. from the air the stockade and half a dozen thatched huts must have looked like one of many similar settlements in a vast sea of green trees stretching to the horizon. But successful South African intelligence had pin-pointed a military camp around the stockade.

Churning up the powdery earth, six Puma helicopters machine-gunned the village and South African troops leaped to the ground in a blaze of firing.

Their work seems to have been brutally efficient. Visiting the camp a week later we saw the burned-out wrecks of seven trucks still close to their dugouts under charred branches, evidence that the defenders had been taken completely by surprise. boots lay at the entrace to foxholes where several men died as they took an affternoon nap. On a metal plate beside cooking pots there were two peeled onions.

A convoy of 100 Angolan troops in two Land Rovers and eight trucks, some of them equipped with antiaircraft guns, drove us for over an hour through the bush to reach the site. Our escorts were taking no chances. At dawn two days after the attack reinforcements sent to the scene had been attacked by another team of eight South African helicopters.

The Angolans were cagey about what happened next. they claim to have shot down three helicopters and an Impala Mark II fighter bomber, but when we asked to see the wreckage they said the South Africans had successfully winched it out by helicopter as they normally try to do to deny the Angolans a propaganda coup.

What was clear beyond doubt was that the camp attacked by the South Africans was entirely Angolan.

Teams of the Southwest Africa People's Organization (SWAPO) that South Africa is fighting in Namibia invariably cross the border into Namibia from their sanctuaries in Angola on foot. SWAPO is not motorized to the same extent as the Angolan Army and has no trucks so close to the border. Strewn around the the camp, dusty and partly burnt, we found handwritten letters and fragments of political pamphlets. Without exception the language was Portuguese, not English which is SWAPO's lingua franca.

From the evidence that is gradually accumulating it is clear that South Africa is conducting a systematic policy of striking economic and military targets in Angola. There can be no more doubt that the broad thrust of Angola's complaints that it is facing South African aggression is true, despite South African denials.

Officially South Africa only admits to occasional attacks within Angola. It says they are aimed exclusively at SWAPO.

Fifteen minutes drive away the Angolans took us the Roman Catholic mission of Cuamato, which was partly staffed by Irish missionaries until the fighting intensified two years ago. Two days after the attack on the settlement South African helicopter gunships swooped down and shot up the mission hospital without landing. All the patients had been evacuated the previous day after the attack on the nearby camp and only one person was wounded.

The Angolans say that South African forces operate regularly inside the country. For the last two months all civilian flights to Ngiva, the capital of Cunene Province have been suspended. Peasants are afraid to cultivate their fields and there are wide-spread food shortages in the entire border region.

Elswhere in Angola, guerrillas of UNITA, the South African-supported movement that was defeated in 1976, still make sporadic attacks. They depend on South African logistical aid.

Recently the South Africans have begun to concede in their communiques that they sometimes kill Angolans although they still say this happens during engagements against SWAPO. On July 31 last year a reporter for the Cape Times who has close contacts with the military high command wrote that the lesson of South Africa's three-week-long incursion into Angola in June was that an Angolan camp no longer meant "Auto-[TEXT OMITTED FROM SOURCE]

This was a change of policy, he said. In the past, he added, South Africa went to great lengths to avoid contact with "host country troops," dropping pamphlets that said South Africa had no quarrel with Angolan civilians and soldiers, only with SWAPO.

One of the many consequences of South Africa's attacks against Angola is that its figures of alleged SWAPO losses of men and equipment are valueless. Unlike the Rhodesians, whose communiques mentioned civilians killed when "caught in cross fire" -- often a euphemism for men and women and children indiscriminately gunned down -- the South Africans never admit that their attacks involve civilian deaths. This blurring of the distinction between civilian and military losses is compounded by failure to distinguish between SWAPO and Angolan casualties. What proportion of the 1,500 SWAPO people South Africa says it killed last year were really SWAPO military forces becomes impossible to know.

On their side, Angolans were told recently by their President Eduardo Jose dos Santos that more than 3,000 Angolans, military and civilian, have been killed by South Africa over the last four years. Angola argues that South Africa's attacks have no conceivable justification. Angolan forces are not fighting either in Namibia nor in South Africa itself.

True, Angola is giving aid and sanctuary to SWAPO and will continue to do so, the Angolans say. But then South Africa maintains forces in Namibia, which it is occupying in defiance of U.N. resolutions, and keeps these forces supplied with conscripts and weapons from across the border in South Africa.