The South African government has called on its Defense Force to try to help break the black unrest that has claimed more than 80 lives since it first erupted in early September.
A combined contingent of 7,000 police and Defense Force troops rumbled into the Sebokeng township south of Johannesburg early Tuesday morning, effectively putting the community under armed rule as police conducted house-to-house searches. By late in the day the operation had been expanded to include two other townships in the area, Sharpeville and Boipatong. About 350 blacks have been arrested so far, according to the South African police.
Such blatant and apparently sizable use of the Defense Force in what would usually be a police responsibility is a new development in the government's battle to end the current black unrest, although it was hinted at earlier.
The use of Defense Force troops in a domestic situation is not unprecedented for South Africa, but it has not been necessary in recent times. For instance, during the black uprising in Soweto in 1976 - considered the country's worst internal security crisis - police were apparently able to handle the situation on their own.
Political analysts here do not believe the South African police are stretched beyond their limits in the present circumstances. Use of Defense Force troops may signal the government has crossed an important threshold, deciding that heavier force is the only answer to current black unrest and that the white electorate by and large supports this approach even if it means using Defense Force troops.
Analysts see the heavy security operation in Sebokeng, Sharpeville, and Boipatong as having two messages:
* Reassuring the country's white minority that the government is moving decisively to end the spate of black unrest that recently claimed its first white victim.
* Telling blacks in effect that the government is fed up with the unrest and will apply ever-increasing force to stop it.
In explaining the initial crackdown on Sebokeng, South African Minister of Law and Order Louis Le Grange said ''criminal and revolutionary elements'' had created a situation of ''lawlessness'' in certain black areas that ''must be curbed with all available means.''
A police spokesman said Sebokeng had been targeted because it was an area where black unrest has been most serious since disturbances began last month. The spokesman said the Defense Force troops were being used only in a ''supportive'' role in the operation in Sebokeng and did not conduct the house-to-house searches.
Sebokeng was one of the worst-hit of five black townships that erupted in riots in September. All the areas affected are in a major industrial complex about 35 miles south of Johannesburg. Destruction in Sebokeng was severe and the community has yet to return to normal.
A police spokesman explained the expansion of the operation into Sharpeville and Boipatong this way: ''Owing to the fact we had the manpower available,'' the police and army also poured into the townships of Sharpeville and Boipatong, about six miles from Sebokeng.
''It's the same operation as in Sebokeng,'' Col. Jaap Venter said.
Unrest has flared in a number of other black areas, most of them in the general vicinity of Johannesburg, since early September. Hardly a day goes by without South African police using tear gas and rubber bullets to disperse small mobs of blacks - usually youths - in one or another township in the area.
South Africa's blacks are in severe economic straits. Unrest is apparently being fueled by black students boycotting classes to protest the segregated education system.
Recent constitutional changes bringing Coloreds (persons of mixed race) and Indians into central government while still excluding the black majority have also angered blacks.
Black community leader Nthato Motlana, chairman of the Soweto Civic Association, said the use of troops in Sebokeng is proof the government has not ''learned the lesson of '76,'' referring to the Soweto uprising of that year. He says the government continues to refuse to talk to the ''authentic leaders'' of blacks and instead locks them up, ''leaving the field to mob rule.''
Mr. Motlana said that if, by sending in troops, the government ''thinks it will pacify the situation, they are making a very stupid mistake.'' He expected the heavy security force action to exacerbate tensions.
The United Democratic Front, a predominantly black organization that opposed the government, said the action in Sebokeng amounted to a ''civil war.'' The front said the action would worsen ''the crisis'' in black townships.
According to the South African police, the 350 people arrested in Sebokeng Tuesday were charged with a variety of offenses ranging from possession of stolen goods and firearms to violation of influx control laws.