In this undated photo, North Korea's new leader, Kim Jong-un, greets students at Mangyongdae Revolutionary School in Pyongyang, North Korea, on the occasion of the Chinese New Year. Compared with his father, who preceded him as president, Mr. Kim is less aloof and more outgoing. (Associated Press)

In this undated photo, North Korea's new leader, Kim Jong-un, greets students at Mangyongdae Revolutionary School in Pyongyang, North Korea, on the occasion of the Chinese New Year. Compared with his father, who preceded him as president, Mr. Kim is less aloof and more outgoing. (Associated Press)