A combat drill of the service personnel of the special operation battalion of KPA Unit 525 is seen in this undated photo released by North Korea's Korean Central News Agency (KCNA) in Pyongyang

A combat drill of the service personnel of the special operation battalion of KPA Unit 525 is seen in this undated photo released by North Korea’s Korean Central News Agency (KCNA) in Pyongyang

A combat drill of the service personnel of the special operation battalion of KPA Unit 525 is seen in this undated photo released by North Korea's Korean Central News Agency (KCNA) in Pyongyang on December 11, 2016. KCNA via REUTERS ATTENTION EDITORS - THIS IMAGE WAS PROVIDED BY A THIRD PARTY. EDITORIAL USE ONLY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THIS IMAGE. NO THIRD PARTY SALES. NOT FOR USE BY REUTERS THIRD PARTY DISTRIBUTORS. SOUTH KOREA OUT. TPX IMAGES OF THE DAY

December 14, 2016 8:08 AM (UTC+8)