Andre Buys is a respected scientist and university professor. He’s a reserved man. But his voice swells with pride as he recalls assembling a secret nuclear weapons arsenal.

“Technically, it was an achievement we were proud of,” he says. “But we weren’t sure whether having a nuclear device was going to be to our advantage or not.”

In the 1980s Buys managed a small team of South African scientists that designed and built six nuclear devices for the country’s apartheid leadership. At the time, most countries were bound by the Nuclear Non-Proliferation Treaty. They agreed not to become nuclear powers. But South Africa stayed outside the treaty. What’s more, the country was isolated diplomatically and under international sanctions for its policy of racial segregation, or apartheid.

But Andre Buys and his team managed to assemble a nuclear arsenal anyway. Their story illustrates how a determined country can develop nuclear weapons, even when it’s cut off from the rest of the world.

“It was technically a big challenge for us,” Buys says. “It was just for scientists and engineers a wonderful technical challenge to be able to be involved in such a program.”

Estimates for the total cost of the South African nuclear bomb program range from $500 million to $1 billion (in early 1980s valuation). Part of the money, according to Buys, went to an international network of smugglers for technology and know-how not available on the domestic market. But Buys’s team wasn’t working from scratch. South Africa already had a vibrant civilian nuclear industry built from technology and know-how imported from the West a decade earlier.

In the 1960s South Africa’s white leaders were looking to strengthen apartheid and modernize the country’s economy. They saw huge potential in exploiting the country’s rich uranium deposits, at first as fuel for their own nuclear energy program. During this period the United States supplied South Africa with the Safari-1 research reactor. The US also provided the reactor with about 100 kilograms of weapon-grade uranium fuel over a ten year period, according to David Albright, president of the Institute for Science and International Security, a Washington-based nuclear watchdog group.

With their nuclear know-how advancing, South African scientists then came across an idea that seems ludicrous today: harnessing so-called peaceful nuclear explosions. The concept was being promoted by the Soviet Union as well as a U.S. Energy Department program known as Operation Plowshare.

As a young engineer fresh out of university, Buys began working on a project inspired by the Plowshare program: to develop explosives for civilian activities such as mining and canal building. But the purpose of his work soon changed.

By the 1970s, South Africa was isolated. The country was fighting proxy wars against Soviet-backed governments in southern Africa. And there was a rising resistance movement among the black majority, which South Africa brutally suppressed with police and army troops. As the U.N. tightened sanctions, South Africa’s embattled leaders ordered Buys and other scientists to divert their efforts into a bomb project. But as he recalls, the leadership didn’t give much guidance on the kind of weapon to build.

“Simple questions like, ‘How many weapons do you need?’ ‘What sort of energy yields?’ Nobody could give us any answers,” he says.

So Buys chaired a working group of top scientists and politicians which honed a nuclear strategy for South Africa. The group met monthly for a year, conducting war games, reviewing nuclear strategy literature and consulting a closely-vetted group of military experts, academics and even a South African theologian, according to an account compiled by political scientist Peter Liberman.

Buys was inspired by the bomb’s technical challenge but he was troubled by its moral implications.

“As the scientists and engineers working on the hardware, we were worried that somebody could use the bomb in an irresponsible way,” he says. “We were just worried as human beings that you make this thing of such tremendous power and you give it to somebody who’s not going to be responsible with it.”

Buys’s working group eventually settled on a three-phase strategy that emphasized using the bomb as a deterrent, and diplomatic cudgel, rather than for possible battlefield deployment. The first phase was “strategic ambiguity”—neither confirming nor denying the bomb, but holding it in reserve in case of a national emergency. Phase two would have involved privately acknowledging the bomb to western powers like Great Britain and the United States in order to win diplomatic backing in a showdown with the Soviets. The third phase, as planned by Buys’s team, would have involved a public demonstration of the bomb such as a detonation over the ocean.

Buys’s bomb lab was established at Kentron Circle, a weapons testing facility located in the rolling foothills west of Pretoria, near the Pelindaba nuclear plant. The site was controlled by Armscor, South Africa’s huge armaments conglomerate.

When scientists assembled the first bomb at Kentron Circle in 1983, Buys recalls, senior government and military leaders secretly celebrated at the facility.

But South Africa never got past the first phase of its nuclear strategy. And Buys says none of the six bombs was ever tested. That’s because by the mid-1980s, wars in Angola and Mozambique were losing steam. And reforms in Moscow reduced concerns about a Soviet threat in Southern Africa. When Frederik de Klerk became president of South Africa in 1989, he ended the program and had the bombs disassembled. South Africa remains the only country in history to voluntarily dismantle an entire nuclear weapons arsenal.

Today, South Africa now plays a big role in the global non-proliferation movement. But nuclear expert David Albright says lessons from the South African bomb program aren’t all comforting. Albright told the Chicago Tribune: “Even though they were complete outcasts, and even though it took them a decade of trial and error, they managed to build weapons of mass destruction with a small, inexpensive and tightly focused program.”

Buys does his part in trying to stop the spread of bomb technology. He now advises other countries on how to dismantle illicit nuclear weapons programs. Several years ago Buys met with a group of North Korean officials as part of a US-sponsored effort to promote nuclear non-proliferation. Buys says he passed on one piece of advice to the North Koreans.

“When you’re busy putting together a secret weapons program, the last thing on your mind is good record-keeping,” he recalls telling the North Korean delegation. “But once you decide to dismantle a nuclear program, you need to prove to the international community that you’ve lived up to your word.”

In other words, Buys advice was to keep a paper trail detailing every step in the building of the bomb.

“Otherwise, who’s to believe you.”

Michael Montgomery

Michael Montgomery is a senior reporter and producer for Reveal. He reports on the criminal justice system, vulnerable populations, and the underground economy. Montgomery has led collaborations with the Associated Press, the International Consortium of Investigative Journalists, Frontline, KQED and others. After completing a Fulbright fellowship in Eastern Europe, Montgomery covered the fall of communism and wars in former Yugoslavia for The Daily Telegraph and Los Angeles Times. He also worked as an associate producer for "60 Minutes" correspondent Ed Bradley and was a senior reporter for American RadioWorks. His investigations into human rights abuses in the Balkans led to the arrest and conviction of Serbian and Albanian paramilitaries and the creation of a new war crimes court in The Hague. As a reporter and producer, Montgomery has garnered national and international prizes, including an Overseas Press Club Award, Investigative Reporters and Editors Certificate, Edward R. Murrow Award, Peabody Award and Alfred I. duPont-Columbia University gold and silver batons. Montgomery is based in Reveal's Emeryville, California, office.