Ambassador Heads to North Korea to Seek Release of Kenneth Bae

The United States is hopeful that a visit to Pyongyang aimed at securing the release of imprisoned American Kenneth Bae will be "straightforward," but a U.S. official speaking on background because of the diplomatic sensitivity of the issue tells CNN there are "no guarantees."

Ambassador Robert King, who's President Obama's special envoy for North Korean human rights issues, will join a small delegation flying to Pyongyang on a U.S. military jet Friday. They are expected to spend 24 hours on the ground, meeting with North Korean officials.

"The sole purpose of the trip is to secure Bae's release," the official says. "Our expectation is that now is the time to move forward and resolve this, to release this American."

Bae has spent more time in North Korean custody than any other American. He has been held since November 2012 and, over the protests of the U.S., was convicted of committing hostile acts against North Korea.

The State Department says North Korea invited the special envoy as part of a "humanitarian mission" to try to free Bae.

In a statement Tuesday, it said that "Ambassador King will request the DPRK pardon Mr. Bae and grant him special amnesty on humanitarian grounds so that he can be reunited with his family and seek medical treatment."

The White House, in a separate statement, said it is urging the government of North Korea "to grant special clemency to Mr. Bae immediately and allow him to return home with Ambassador King."