Nelson Mandela and his wife, Winnie, raise clenched fists as...

Nelson Mandela and his wife, Winnie, raise clenched fists as they walk hand-in-hand upon his release from prison in Cape Town, South Africa. Credit: AP, 1990

In 1993, on the eve of black majority rule in South Africa, Time magazine asked Nelson Mandela if economic sanctions helped speed the demise of the country's apartheid system.

"Oh, there is no doubt," Mandela said.

Throughout his 27 years in prison -- and until he became president of South Africa -- Mandela unequivocally supported sanctions as a weapon of global justice. Yet we've heard almost nothing about that legacy amid all the paeans to Mandela, who is being buried Sunday.

That reflects our cynicism about sanctions. From Iran and Syria to Cuba and North Korea, the conventional wisdom goes, American and international sanctions haven't necessarily accomplished their goals.

And in some cases, that's true. More than a half-century after the U.S. slapped sanctions on Cuba, for example, Fidel Castro and his brother Raul remain in power. But as the South African example attests, sanctions also can force progress and change.

That's what exiled African National Congress leader Oliver Tambo told Nelson Mandela in the 1980s, near the end of Mandela's prison term. "Don't maneuver yourself into a situation where we have to abandon sanctions," Tambo wrote Mandela, who had opened secret negotiations with South African president P.W. Botha, according to a published account of the events. "We are very concerned that we should not get stripped of our weapons of struggle, and the most important of these is sanctions."

So Mandela held firm. And after he was released in 1990, he continued to press for sanctions against South Africa. "To lift sanctions now would be to run the risk of aborting the process towards the complete eradication of apartheid," Mandela declared in his first public speech upon leaving prison.

And he repeated the message later that year in his trip to the United States, which had instituted sanctions on South Africa in 1986 over President Ronald Reagan's veto. Like many opponents of sanctions today, Reagan insisted that they would harm -- not protect -- the victims of oppression.

Mandela wasn't having it. "We still have a struggle on our hands," Mandela told a joint session of Congress in 1991 as he insisted on sanctions. And the following year, when President George H.W. Bush lifted them, Mandela blasted him for acting prematurely.

Only with the establishment of a 1993 transitional executive council in South Africa, which set the state for multi-racial democracy, would Mandela call for an end to sanctions. Yet he continued to claim that they had provided an important boost for black freedom in South Africa, praising the "millions of people across the globe" who had demanded them.

Those people included a young African American at Occidental College in Los Angeles named Barack Obama, who spoke at a 1981 rally condemning the college's investments in companies that worked in South Africa. "I am one of the countless millions who drew inspiration from Nelson Mandela's life," President Obama recalled, after Mandela died. "My very first political action, the first thing I ever did that involved an issue or a policy or politics, was a protest against apartheid."

But it was also a protest against Americans who did business with apartheid. I participated in similar divestment rallies over the next two years at Columbia, where Obama became my classmate. We didn't know each other, but we believed that blocking economic activity in a tyrannical country would eventually bring about change.

And there's plenty of evidence that we were right, in South Africa and elsewhere. Consider Iran, where sanctions surely played a part in forging the recent nuclear pact with the United States.

We still don't know whether Iran will limit its nuclear program, as it promised. But the promise itself is a product of international sanctions. Does anyone think Iran would have agreed to destroy some of its highly enriched uranium, without the stick of economic sanctions and the carrot of seeing them lifted?

So the next time you hear a pundit on TV say that "sanctions never work," think again. Think of those whose support for sanctions helped remove a hateful regime from South Africa. And think most of all of Nelson Mandela, who never doubted that we could join hands to change the world.

Jonathan Zimmerman teaches history and education at New York University. He is the author of "Small Wonder: The Little Red Schoolhouse in History and Memory" (Yale University Press).