THE SOUTH AFRICAN government, soliciting understanding for its punishing air strike into Mozambique, says it was responding to terrorism, specifically, to the car bomb that went off near air force headquarters in downtown Pretoria last Friday, killing 17 persons, many of them civilians and many blacks. But it deserves little sympathy. No act of terrorism can be justified. Yet plainly in South Africa special factors operate. The racist system by which the white minority rules is evil, and the blacks who are its principal victims have virtually no possibility of changing it peacefully. South Africa appeals for support on the basis that it is combating something, terrorism, to which all civilized peoples must be opposed. But terrorism is, in its South African incarnation, something the South Africans have created themselves.

The American government's response yesterday was unsatisfactory. The State Department said that "these acts"--the car bomb and the air strike-- made it necessary to halt the region's "escalating cycle of violence." But it is not a "cycle of violence," a back-and-forth thing where the two sides have similar responsibilities and similar political and moral weights. It starts in a single known place: in the particular pervasive form of white violence-- apartheid--that has driven some blacks to another, more dramatic form--terrorism.

Black nationalists necessarily have some links with countries on South Africa's borders. Those governments are not strong enough to prevent entirely the use of their territory for sanctuary, even if they wanted to.

The State Department, pointing to recent ministerial-level meetings between South Africa and Mozambique, suggests that "only through discussions among the states of the region" can the "underlying" tensions be reduced. That formulation goes a long way toward accepting South Africa's premises. In fact, though the administration's policy of "constructive engagement" may make it hesitate to so acknowledge, the primary tensions are not tensions of the region but tensions bred by apartheid within South Africa. Discussions among the states of the region have their usefulness and even their necessity, but the only discussions that can possibly start reducing the "underlying" tensions are those between the different groups within South Africa itself. As long as white South Africa rejects any sort of discussions at all with its black majority, it can probably expect no respite.