Jang Jong Nam, an unknown field commander in his 50's, was introduced as minister of the People's Armed Forces at a function attended by North Korean leader Kim Jong Un, the South Korea's Yonhap news agency reported Monday, citing a report from the North Korean state news agency.
The position is equivalent to defense minister.
Gen. Kim Kyok-Sik, 70, had been appointed to the position several months ago. Only four days before Jang was introduced as defense minister, Kim attended a state ceremony as armed forces chief.
An analyst in Seoul speculated Jang's appointment could indicate Pyongyang wants younger officers in charge or that North Korea may be trying to cool diplomatic tensions by replacing Kim, who was seen as a hard-liner.
Jang was promoted to major general in 2002 and to lieutenant general in 2011.
Pyongyang last week lifted its high state of military readiness instituted in response to joint war games conducted by the United States and South Korea.