CUITO CUANAVALE, ANGOLA -- Maj. Armindo Moreira strode to the center of a patched-together bridge and waved a hand toward a hillside of mud-and-thatch huts.

"We brought you here," said the Angolan Army officer to visiting reporters, "to show you that we still control Cuito Cuanavale."

Behind him, a dozen South African artillery shells screamed out of a dark cloud and raised great columns of white smoke on the valley floor less than a mile away. The bridge over the fast-flowing Cuito River reportedly has been bombarded so many times in recent weeks that the Angolans no longer rebuild it, crossing from the town to their forward positions on a catwalk.

Some of the civilian population still live in this tiny town, besieged for three months by the South African Defense Force and rebels of the Union for the Total Independence of Angola (UNITA). Women were lighting fires outside their huts Sunday, and children waved from cornfields at passing armored personnel carriers.

The town's size and shabbiness belie its importance. Although South Africa's troops, armor and artillery are the most sophisticated in the region, the South African Defense Force is said to lack air supremacy. Angola's modern MiG fighters, considered more than a match for South Africa's aging Mirages, are deployed at bases that extend across the southern portion of the country from the Atlantic Ocean.

The southernmost base is at Cuito Cuanavale, where the airstrip is paved and, owing to constant repairs, intact. Loss of the base to South Africa would put a major crack in Angola's defense perimeter.

Angolan and Cuban units, dug in along the 60 miles of paved road from here to the provincial capital of Menongue, are said to be bringing in reinforcements and bracing for a major attack.

The first foreign journalists to visit the area since the battle began in August traveled the route Sunday in Soviet-made helicopters and armored personnel carriers. We saw a column of tanks, mounted artillery and at least 300 supply trucks rolling toward the beleaguered town.

South African and UNITA forces, said to be at least 6,000 strong, reportedly have stepped up their daily air and artillery bombardments from a base 20 miles east of Cuito Cuanavale and they man forward positions behind a wooded ridge just five miles from the town. Moreira said his men repulsed a ground attack in a fierce firefight last Tuesday.

"The South Africans are concentrating in Cuando Cubango Province for a big attack," said provincial commissar Manuel Francisco Tuta, whose nom de guerre is "Battle of Angola." "The situation is still threatening, but . . . we're beating them."

Tuta's high morale appears to be shared by his troops. Though muddy and unshaven, they appeared well fed, well equipped and in high spirits. Many flashed the thumbs-up sign at the visitors' personnel carrier.

The siege of Cuito Cuanavale grew out of an offensive launched in August by Angolan troops, supported by their Soviet and Cuban allies. South African aircraft came to the defense of the UNITA base in Mavinga, which had been routed by the Angolans. The South Africans pursued the Angolans northward to Cuito Cuanavale. Here the Angolans dug in, backed by Cuban troops who, according to Tuta, have since assumed an active role in the fighting "at all levels."

Cuban-manned Pechora missiles and the heavy, truck-mounted rocket launchers, called "Stalin organs," with clusters of firing tubes, have inflicted severe damage on the South African Air Force, according to Angolan military officers. The Angolans claim to have shot down more than 20 fighter aircraft since the beginning of the advance on Cuito Cuanavale.

But Angolan losses apparently have been heavy as well. The bush on either side of the road to Cuito Cuanavale bristles with radar and dug-in tanks and artillery, and MiG21 and 23 fighters stand ready at Menongue Airport. But the roadside is also pocked with bomb craters and littered with the burned wreckage of oil tankers and supply trucks.

From a helicopter, the thick scrub forest and desolate marshlands of Cuando Cubano Province seem an unlikely prize to inspire such fierce fighting. The Portuguese colonialists called this sparsely populated region "lands at the end of the Earth."

But Cuito Cuanavale has assumed a symbolic significance even beyond its strategic value, with the Angolans vowing to hold it and the South Africans appearing determined to take it.

So this shell-shocked shadow of a former bustling farming center cringes at the focus of a growing conflict. People's Store Number Two is still intact, and the water tower proclaiming the town's name is unscathed, but most of the stucco colonial buildings that once lined the main street are bombed-out ruins.