White House working to confirm hard labor sentence for American in North Korea

Bae has been detained for more than six months, and high-profile Americans — including former U.N. Ambassador Bill Richardson and Google chairman Eric Schmidt — have asked Pyongyang to release the tour operator. But some foreign policy experts have suggested his sentencing is a ploy to get the United States back to the negotiation table, in hopes of removing sanctions put in place following a nuclear test earlier this year.

Carney refused to speculate on North Korea's motives when pressed by reporters.

"We have made clear that there is a path open to the North Koreans that would allow for negotiations, but it is dependent upon the North Koreans demonstrating a willingness to live up to their international obligations," Carney said. "But thus far, as you know, they have flouted their obligations, engaged in provocative actions and rhetoric that brings them no closer to a situation where they can improve the lot of the North Korean people or reenter the community of nations."

In 2009, journalists Laura Ling and Euna Lee were sentenced to 12 years of hard labor after being captured crossing the border with China while making a documentary about North Korean defectors. Former President Clinton traveled to Pyongyang to negotiate their release.