Former president Jimmy Carter (D) said Wednesday that he would consider pardoning Edward Snowden if he returned to the United States and was convicted and sentenced, but acknowledged he doesn't have enough information to judge how much damage the former National Security Agency contractor has done to U.S. national security interests.

"If he was found guilty and sentenced to death, I would certainly consider pardon," Carter said. But, Carter added that he doesn't have "the information President Obama has about what damage has been done to our security apparatus."

When asked whether he would pardon Snowden today as president, Carter replied, "No, because you can't pardon someone who has not been tried and convicted."

Carter made his remarks during an appearance at The Washington Post. He's been making the rounds to promote his new book, "A Call to Action: Women, Religion, Violence and Power." The discussion, which also focused heavily on women's issues and religion, was moderated by David Ignatius and Sally Quinn.

Carter has been a critic of the NSA surveillance efforts revealed by Snowden, who is living in Russia. The former president recently said that he believes the agency is monitoring his e-mails. On Wednesday, Carter called on Obama to do more to scale back the scope of government surveillance.

"I would like to see him do it by executive order which I think he could," Carter said.

On the situation in Ukraine, Carter reiterated his belief that the United States and its allies could not have done anything to stop Crimea from falling into Russia's hands. But, he added that Russian President Vladimir Putin "has to be stopped now." He said that while the threat of U.S. military force to prevent Russia from moving further into Ukraine is probably excessive, showing support for the Ukrainian military in concert with U.S. allies is prudent.

"I think it would be legitimate to say we are going to make sure the Ukraine military are fortified and [provided with] whatever weapons they need," said Carter.

On Middle East peace efforts, Carter urged Obama to adopt a robust posture in support of his chief diplomat if he comes forth with a comprehensive peace plan in the region.

"He doesn't have to be involved in the negotiations," said Carter, "but he has to make sure once [Secretary of State] John Kerry comes forward with a roadmap ... that he lets the whole world know this is the United States position."