S. Africa thumps Botswana; cites insurgents as target. CROSS-BORDER STRIKE

South African commandos yesterday killed four people in a cross-border incursion into neighboring Botswana, the third attack on that country in three years. The raid was seen by diplomats as a fulfilment of a recent pledge by South African Minister of Defense Magnus Malan to pursue and destroy guerrillas of the outlawed African National Congress. ``Wherever the ANC is, we will eliminate it,'' General Malan said.

That declaration represented a perceptible hardening of attitude on regional issues and served as a kind of counterpoint to an ongoing domestic crackdown.

Acknowledging responsibility for Monday's attack, the South African military presented the raid as a ``hot pursuit'' operation after a clash on the Botswana border last Friday between a South African patrol and an ANC guerrilla unit.

``South Africa has shown its determination not to allow infiltration, as it sees it, from across the border, and to assert its right to hot pursuit,'' a well-placed diplomat here said. He dismissed speculation that the raid was timed to impress supporters of the ruling National Party in a by-election today.

Three guerrillas were killed in Friday's clash and, according to the military, information was obtained which identified another ANC target: a house on the outskirts of Gaborone, Botswana's capital. The house and its alleged ANC occupants was ``further evidence that ANC terrorists, originating from Zambia and Zimbabwe, use Botswana as a transit route to infiltrate into South Africa.''

Botswana officials confirmed that four people had been killed by the raiders but were unable to give further details immediately.

Diplomatic sources in Gaborone reported that there were five people in the house - four Botswana nationals and one South African refugee. The South African managed to escape, one embassy reported.

South Africa has been trying for years to persuade Botswana to sign a non-aggression pact along the lines of agreements signed with Mozambique in 1984 and with Swaziland in 1982. But Botswana has resisted, fearing that it will be dragooned into playing the role of Pretoria's policeman over its own territory.

South Africa has repeatedly accused Botswana of allowing ANC fighters to transit through its territory en route to or from South Africa. Botswana has countered that it does not give free passage to guerrillas, contending that if guerrillas entered South Africa from Botswana it is because they successfully evaded Botswana security forces in the same way as they slipped past South African patrols.

There were widespread fears three months ago that the ANC was planning an offensive from Botswana and that it could trigger a major counterattack on Botswana by South Africa security forces. A spokesman for the South African Department of Foreign Affairs confirmed that South Africa had formally warned Botswana of the consequences of an ANC attack from Botswana's soil.

The attack failed to materialize, perhaps because of stepped-up vigilance by South African border patrols, or perhaps - as the ANC insisted - because one was not planned from Botswana.

South Africa's raid was foreshadowed by several blunt warnings from Malan and, more recently, from Minister of Foreign Affairs, Roelof Botha. The latest warning came last month after a rocket attack on a farmhouse near South Africa's border with Zimbabwe.

Mr. Botha's role in echoing earlier warnings from Malan was seen as giving the imprimatur of his more dovish department to the bellicose stance of the military. Botha could hardly have put it more bluntly: ``Enough is enough. Next time we send in our troops.''