Johannesburg — A powerful car bomb explosion has punctured the sense of near euphoria that has permeated South Africa in recent months. The bombing in the port city of Durban, South Africa, claimed three lives and served as an unpleasant reminder to this country's ruling whites that black guerrilla activity may slacken but is unlikely to disappear despite the government's regional gains in countering black insurgency. At its root, some analysts say, black guerrilla violence is an internal phenomenon and its causes remain basically unaddressed.
The explosion occurred Tuesday during Durban's morning rush hour. It is widely assumed that the sponsor of the bombing is the African National Congress.
The ANC, which is officially banned by the South African government, has vowed to step up its attacks in this country even though the organization is finding that black neighboring states which previously offered sanctuary now are less willing to offer this sort of cover.
The Durban attack found much of South Africa, particularly the whites, basking in a feeling of confidence that ANC violence had been shut off.
That confidence was born of the government's recent successes in neutralizing black neighboring states. Using military and economic pressures, South Africa has forced its neighbors to deny the ANC any bases for military activity against South Africa.
The white government's most dramatic achievement was the signing of a nonaggression pact last month with Mozambique, the source of the majority of ANC attacks in the past. More recently, South Africa disclosed that it has had a similar but secret security agreement with Swaziland for two years.
The South African government's strategy appears to be to make it impossible for the ANC to act militarily, thus hoping to reduce the group's sizable base of political support and sympathy among blacks in South Africa.
The weakness of the government's strategy is that it contains no political complement of reforms that would lessen black anger and frustration.
If anything, South Africa's internal policies seem to be hardening black resistance and generating more support for the revolutionary changes promoted by the ANC.
In the wake of the so-called Nkomati Accord between Mozambique and South Africa, Mozambique has raided the homes of ANC members.
The apparent Mozambique crackdown on the ANC has sent some rebel fighters fleeing into Swaziland in recent days, leading to detention of at least 16 suspected ANC members in that country.
South Africa's regional successes are seen by analysts here as by and large depriving the ANC of a regional infrastructure for funneling arms and men into South Africa and planning attacks against the country. The Durban bombing may be evidence of this.
''It was to be expected that the ANC would try to make a big impact with whatever local reserves it still has available,'' says Tom Lodge, a political scientist at the University of the Witwatersrand in Johannesburg.
But Professor Lodge has doubts that the creation of a regional buffer zone will completely seal off the ANC. Rather, he expects it will simply make sabotage attacks ''much more difficult'' and therefore less frequent.
Government sources say guerrilla attacks were at their highest level in 1983, with some 55 incidents recorded.
The as yet unanswered question is how the ANC will respond to regional developments. Sabotage attacks have served to inspire admiration among South African and southern African blacks since the ANC's attacks began in earnest in 1977. But given the new difficulties, the ANC may be forced to put more effort into direct political organizing, analysts say.
The Durban attack was only one of a handful of recorded sabotage incidents in 1984 - an apparent indication of the effectiveness of South Africa's regional strategy.
However, the Durban bombing is considered a major incident since it claimed civilian lives - something the ANC seemed to try to avoid in the past.
The attack is fueling speculation as to whether it fits a new pattern of the ANC being less concerned about civilian casualties.
Some experts feel the black nationalist organization established such a new approach with a bombing last May in downtown Pretoria that claimed 18 lives.
The main targets of the Durban bombing - government offices - are typical of the ANC.