Story highlights The former president tells CNN that Snowden has hurt U.S. security

He refrains from criticizing Obama, who he says has a "hard job"

Nelson Mandela's legacy "will last for a long time," Bush says

He says he bears no grudge against Mandela for Iraq criticism

Former President George W. Bush and his wife, Laura, are in Africa this week, where they renovated a cancer screening clinic in Zambia and commemorated the victims of the 1998 U.S. Embassy bombing in Tanzania.

The clinic, which is designed help women fight cervical cancer, builds on the former president's work fighting AIDS on the continent. While he was in office, Bush set up a plan that dramatically reduced the number of AIDS deaths in Africa.

"I'm really proud of the American people for their generosity," he told CNN in an exclusive interview. "I wish Americans knew how many lives were saved. Someday, they will."

Bush also told CNN why he respects Nelson Mandela, what he thinks about Edward Snowden and President Barack Obama, and how he's not going to be around when his legacy is finally decided.

• On Snowden: "I think he damaged the security of the country."

Photos: Photos: Bushes renovate Zambian clinic Photos: Photos: Bushes renovate Zambian clinic Bushes renovate Zambian clinic – For two days, former President George W. Bush and first lady Laura Bush worked alongside Zambians, U.S. embassy officials and the Bush Institute staff to renovate the Mosi Oa Tuny Clinic. It will serve as a cervical cancer screening and treatment center in Livingstone, Zambia, continuing the global health initiative at the George W. Bush Institute. Above, Bush does some touch-up work. Click through the gallery for more pictures from their June 29-30 visit: Hide Caption 1 of 8 Photos: Photos: Bushes renovate Zambian clinic Bushes renovate Zambian clinic – This is the second time the Bushes came to Zambia on a health mission. Last July, they renovated and opened the NguNgu Health Center in Kabwe, Zambia. Hide Caption 2 of 8 Photos: Photos: Bushes renovate Zambian clinic Bushes renovate Zambian clinic – Bush visits the Cathedral of St. Theresa Catholic Church in Livingstone. Hide Caption 3 of 8 Photos: Photos: Bushes renovate Zambian clinic Bushes renovate Zambian clinic – The project is in direct support of the Pink Ribbon Red Ribbon partnership, which combats cervical and breast cancer in the developing world. It's spearheaded by the Bush Institute, PEPFAR, UNAIDS and Susan G. Komen for the Cure, along with other private and public partners. Hide Caption 4 of 8 Photos: Photos: Bushes renovate Zambian clinic Bushes renovate Zambian clinic – The clinic in Livingstone was scheduled to open to the public on Monday, July 1. Hide Caption 5 of 8 Photos: Photos: Bushes renovate Zambian clinic Bushes renovate Zambian clinic – Laura Bush pauses at the Mosi Oa Tuny Clinic. Hide Caption 6 of 8 Photos: Photos: Bushes renovate Zambian clinic Bushes renovate Zambian clinic – George W. Bush does some painting during renovations. Hide Caption 7 of 8 Photos: Photos: Bushes renovate Zambian clinic Bushes renovate Zambian clinic – After their trip to Zambia, the Bushes will travel to Dar es Salaam, Tanzania, to host the Bush Institute's African First Ladies Summit. The theme is "Investing in Women: Strengthening Africa." Hide Caption 8 of 8

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• On Mandela: "His legacy will last for a long time."

• On Obama: "It's a hard job. He's got plenty on his agenda."

Bush talked about Snowden, the computer contractor who leaked details about secret U.S. surveillance programs, to CNN's Robyn Curnow in Zambia on Sunday.

He said he believes the Obama administration "will deal" with the fallout from the controversy unleashed by Snowden, who is now thought to be holed up in the transit area of a Moscow airport after fleeing there from Hong Kong.

Snowden's disclosures about the programs carried out by the National Security Agency have shaken the U.S. intelligence community and put the Obama administration on the defensive over accusations of government overreach into citizens' privacy.

But Bush refrained from criticizing the current president.

"I don't think it does any good," he said. "It's a hard job. He's got plenty on his agenda. It's difficult. A former president doesn't need to make it any harder. Other presidents have taken different decisions; that's mine."

The White House has defended the surveillance programs as necessary tools to defuse terrorist threats. Obama has said he welcomes a debate over how to strike a balance between security and privacy.

"I think there needs to be a balance, and as the president explained, there is a proper balance," Bush said.

Asked about an NSA program that tracks people's Internet activity, Bush said, "I put that program in place to protect the country. One of the certainties was that civil liberties were guaranteed."

Snowden has said he leaked information to journalists about the surveillance programs in the hope of ending what he called an excessively intrusive system.

The Bushes were at a renovated health clinic in Livingstone, Zambia, scheduled to open Monday as a cervical cancer screening and treatment center. They hope this will save the lives of thousands of women.

In his comments, George Bush touched on the subject of Mandela, who is on life support in a South African hospital.

"Sometimes, there are leaders who come and go. His legacy will last for a long time," he said of the ailing anti-apartheid icon.

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Reminded by Curnow that Mandela had criticized him publicly about the war in Iraq, Bush said he didn't bear a grudge.

"He wasn't the only guy," he said. "It's OK. I made decisions that were the right decisions. History will ultimately judge. I never held someone's opinion against him; I didn't look at him differently because he didn't agree with me on an issue."

Bush also initially said he wasn't bothered about his ratings in opinion polls, even if some of them now put him at a similar level to Obama.

"The only time I really cared was on Election Day," he said.

Then, drawing laughter from his wife, he checked himself and said, "You know, I guess it's nice. I mean, let me rephrase that: Thank you for bringing it up."

In any case, the former president said he doesn't expect a fair assessment of his legacy in his lifetime.

"I won't be around, because it will take a while for the objective historians to show up," he said. "So I'm pretty comfortable with it, I did what I did; I know the spirit in which I did it."