North Korean leader Kim Jong-un (center) waves during his visit to the Korean People's Army (KPA) Air Force Unit 354 at an undisclosed location in North Korea in this undated photo. (AP Photo/Korean Central News Agency via Korea News Service)

North Korean leader Kim Jong-un (center) waves during his visit to the Korean People's Army (KPA) Air Force Unit 354 at an undisclosed location in North Korea in this undated photo. (AP Photo/Korean Central News Agency via Korea News Service)