IN ITS far-flung campaign to stem the tide of black majority rule, South Africa has often turned to covert operations. In recent years, it has backed guerrilla armies in Angola and Mozambique, launched periodic commando raids on neighboring capitals and disrupted vital rail and fuel lines throughout the region. But another dimension to South Africa's war against its neighbors is less well known. It is a subtle, cynical strategy of tinkering with ethnic tensions -- an international version of apartheid's domestic system of divide and rule. The consequences of this strategy, at least in neighboring black-ruled Zimbabwe, provide a sobering reminder of the lethal potential of ethnic and racial politics in southern Africa at a time when talk in the region is shifting toward accommodation. A series of recent Zimbabwean court cases have disclosed evidence of South African penetration at the highest reaches of Zimbabwe's domestic intelligence agency, the Central Intelligence Organization (CIO). They suggest that South African agents, by manipulating intelligence reports and fanning ethnic strife, may have played a larger role than previously suspected in touching off a bitter five-year post-independence bush war in the southwest provinces of Matabeleland. That war killed hundreds of civilians, badly damaged Zimbabwe's international image and nearly derailed the young nation's efforts to build a prosperous and peaceful multiracial society. The key players in this alleged scheme were former agents of the Rhodesian secret police, some of whom stayed in Zimbabwe after independence and continued, unaccountably, to work for Zimbabwe's intelligence services. This was the same police force that in the 1970s created the infamous guerrilla group, the Mozambican National Resistance (RENAMO). "It's the same enemies we were fighting all along that have carried out this war against us," said Dumiso DAbengwa, who was detained without charges for four years in a Zimbabwean prison after he was acquitted of treason in a celebrated 1983 trial. This is a complex tale of intrigue and shifting historical currents; its veracity probably will never be proved. Some of its key details are ambiguous, in part because they emerged in signed confessions that were later tainted by evidence of torture. This was itself a legacy of Ian Smith's secret police, whose interrogation methods outlasted the system of white privilege they were designed to preserve. A major irony is that the government of Zimbabwe, not one to rush to South Africa's defense, disputes this story. For although Zimbabwean officials have always maintained that South Africa sought to aggravate the conflict once it had started, they deny that South African agents had a hand in touching off the Matabeleland conflict. They are loath to acknowledge that they may have been duped, and they deny that they allowed former Rhodesian spies to play a prominent role in their newly independent regime. Officials note that the accused Dabengwa, among others, has an interest in placing blame elsewhere. Nevertheless, Zimbabwean officials concede that it was clearly in South Africa's interest, and consistent with its wider policy in the region, to keep a hostile, avowedly radical black-ruled neighbor divided and preoccupied with its own problems. And they also concede that South Africa had a particular interest in undermining the Zimbabwean Peoples Revolutionary Army (ZIPRA), one of the two ethnically based, black nationalist guerrilla armies that fought in an uneasy alliance against white rule in Rhodesia's civil war. ZIPRA had a history of close ties with the African National Congress (ANC), the main guerrilla group fighting against white rule in South Africa, dating back to their days together as Moscow-backed insurgencies based in Zambia. Dumiso Dabengwa was ZIPRA's former intelligence chief and its popular leader. At Dabengwa's treason trial, government prosecutors -- relying heavily on intelligence provided by former Rhodesians in the CIO -- sought to prove that Dabengwa and his former comrades-in-arms were plotting a violent overthrow of the new black-led regime. The trial revolved around the discovery, in February 1982, of large arms caches on property owned by ZIPRA's political wing, the Zimbabwean African People's Union (ZAPU). This discovery was the final straw that touched off the conflict in Matabeleland. Within weeks, Mugabe sacked the opposition leader, Joshua Nkomo, from his cabinet and arrested Dabengwa and others. Soon hundreds of former ZIPRA combatants deserted the national army and went into the bush in Matabeleland, their home turf, where they waged a sporadic campaign of murder and sabotage. The government responded brutally, killing hundreds of Ndebele civilians. The violence ended in December 1987 with a negotiated merger of the country's two main political parties, Mugabe's Zimbabwean African National Union (ZANU) and Nkomo's ZAPU. Meanwhile, Dabengwa's acquittal and subsequent redetention without charges left basic historical questions in dispute, including the trial's central question: Who cached the arms and why? Dabengwa had claimed that the arms were cached in self-defense by former ZIPRA combatants, members of the minority Ndebele tribe, who feared attacks by their long-standing rivals in the Zimbabwean African National Liberation Army (ZANLA), the other, large black nationalist guerrilla army that had been led by Robert Mugabe. ZANLA's rank-and-file were drawn mostly from the majority Shona-speaking tribes. The trial judge called Dabengwa's actions during the period in dispute "the antithesis of {a person} scheming to overthrow the government." He noted that the two most important state witnesses, on whose testimony the failed prosecution largely rested, testified that they had been "pressured" to implicate Debengwa. But Mugabe's government rejected this verdict, and spent the next four years trying to crush an insurgency that had no acknowledged leaders, no avowed political aims, and no admitted followers. Despite hundreds of arrests and ruthless interrogations, the government was never able to establish an explicit link between the insurgents and either ZIPRA's leadership or ZAPU. Only gradually did it become apparent that former Rhodesians in key positions in the CIO, with direct responsiblity for Matabeleland, had been working simultaneously for South Africa. During the Rhodesian civil war, Rhodesia and South Africa were blood allies. The South Africans worked intimately with the Rhodesian security services -- as with many other Rhodesian institutions. After independence, some 5,000 Rhodesians with military and intelligence links -- black and white -- are believed to have crossed the border into South Africa. Many of these former Rhodesians soon joined up with units of South Africa's military and intelligence forces. Some of their old compatriots, meanwhile, stayed behind in newly independent Zimbabwe, and a surprising number of these continued to play key roles in Zimbabwe's security apparatus. Emmerson Munangagwa, who served as Zimbabwe's security minister throughout the conflict in Matabeleland, confirmed in an interview that South Africa had a "major implant in intelligence under Smith" and that "they initially left these implants." Why were they allowed to stay on in the CIO? "We had no choice," Munangagwa said. "We could not allow our whole intelligence capability to collapse overnight." It soon became clear, however, that some of these former Rhodesian holdovers were cooperating with their former comrades in South Africa. The evidence includes: The August 1981 assassination of Joe Gqabi, a representative of the ANC in Zimbabwe's capital city of Harare. A small cell of whites then serving in the CIO had supplied important intelligence for the assassination. The cell was led by a former Rhodesian intelligence officer named Geoffrey Price, who stayed on after independence and served as director of "close security" in the CIO. He was responsible, remarkably, for Prime Minister Mugabe's personal security. Soon after the assassination, Price fled Zimbabwe for Britain and later settled in South Africa. A series of explosions, less than two weeks after Joe Gqabi's assassination, that destroyed $36 million worth of armaments at the Inkomo Barracks near Harare. A police investigation led to the arrest of a former Rhodesian officer, Captain Frank Gericke, who stayed on in the Zimbabwe National Army in the corps of engineers, in charge of the armory at Inkomo Barracks. But Gericke was able to flee the country, and at last report had joined the South African Defense Forces. The December 1981 bomb explosion on the roof of the headquarters of ZANU that killed six shoppers nearby. Police investigators concluded that the operation was carried out by former members of the Rhodesian SAS. The destruction, in July 1982, of nearly a third of Zimbabwe's air force in a bomb attack at the Thornhill air base in Zimbabwe's midlands. Four former Rhodesian airmen were later charged with sabotage on behalf of South Africa. They were acquitted on grounds that their confessions had been coerced, and they were briefly detained under Smith's old emergency laws. The following year a former Rhodesian intelligence agent was directly connected to the conflict in Matabeleland. He was Malcolm "Matt" Calloway, a former agent of the Rhodesian Special Branch who stayed on after independence and joined the CIO. Calloway fled Zimbabwe in late 1982 for South Africa, where he joined South African intelligence. A year later Zimbabwean officials announced that Calloway was linked to an operation in South Africa's northern Transvaal, near the Zimbabwe border, that recruited and trained dissaffected Ndebeles and sent them back into Matabeleland as armed insurgents, known as "Super-ZAPU." In fact, Matt Calloway's fingerprints were evident at the very beginning of the conflict in Matabeleland, when he was still in Zimbabwe. Before his flight to South Africa, Calloway was the CIO's head agent in the western coal-mining district of Hwenge. It was in this district that the arms caches were discovered. Thus the man Zimbabwe accused of organizing "Super-ZAPU" in South Africa had played a role in the discovery of the arms caches -- and in interpreting their significance. Calloway, along with Geoffrey Price, the former head of "close security" who fled to South Africa shortly before the discovery was announced, was instrumental in investigating the arms caches and in recommending that Dabengwa and the others be prosecuted for treason. A final piece of the puzzle has emerged within the past year in a case now on appeal before Zimbabwe's Supreme Court. Kevin Woods, a former Rhodesian intelligence agent, had served in the CIO until 1986. In 1988 Woods was arrested and accused of participating in a car bomb attack against an ANC target in Bulawayo. At his trial Woods confessed to serving as a double agent for South Africa. Woods' confession -- given freely, he said, because he feared interrogation methods with which he was all too familiar -- cast new light on the extensive South African penetration of Zimbabwe's intelligence apparatus in key positions relating to the conflict in Matabeleland. Woods had been the top CIO administrative officer in Bulawayo, the main city in Matabeleland, throughout most of the conflict there. Thus three key players responsible for the intelligence on which the unsuccessful Dabengwa prosecution was based -- and from which so much conflict inexorably followed -- have since turned out to be double agents for South Africa: Matt Calloway, Geoffrey Price, and now Kevin Woods. South Africa has always denied any involvement in the conflict in Matabeleland. A spokesman for the South African Embassy in Washington dismissed these allegations as "a load of nonsense." Skeptics of a South African conspiracy theory properly warn against overestimating South Africa's ability to manipulate events in another country with its own complex politics and a large cast of characters. To be sure, the conflict in Matebeleland was by no means all South Africa's fault; primary responsibility must fall on the Zimbabweans themselves. During the last year South Africa has extended a more conciliatory hand toward its neighbors, most notably in Angola and Mozambique. But the case of Kevin Woods, and the recent, turbulent history it harkens back to, serves as a reminder of just what a potent stick Pretoria has been prepared to wield in the recent past, and just how invitingly self-destructive these neighbors have proven themselves to be. Bill Berkeley is the author of "Zimbabwe: Wages of War," published in 1986 by the Lawyers Committee for Human Rights.