North Korea's abrupt promotion of an army general in charge of border defense to the rank of vice marshal signals a shift in power structure in the reclusive communist state led by the young, untested leader Kim Jong-un, senior officials here said Tuesday.

The North's state media KCNA on Tuesday said Hyon Yong-chol was awarded the title of vice marshal of the Korean People's Army, one day after it announced Vice Marshal Ri Yong-ho, the top military commander, was relieved of all of his posts.

Illness was given as the official reason for the 70-year-old Ri's departure, but analysts expressed skepticism, saying the move showed the young leader tightening his control over the powerful military.

Little is known about Hyon, who became a general in September 2010 along with five others including new leader Kim Jong-un and his aunt Kim Kyong-hui. Hyon had been drawing attention as one of the key figures expected to help the junior Kim gain control over the military.

According to a senior military official in Seoul, Hyon served as a commander of an army corps near its northeastern border with China and is believed to be in his early 60s.

Considering Hyon's battlefield experience, the official said, Pyongyang is expected to maintain its hostile stance toward Seoul.

"Promoting a field-grade officer to a key military post signals that Kim Jong-un is attempting to reorganize the military structure with figures close to him," the senior official said, requesting anonymity due to the sensitivity of the issue.

Baek Seung-joo of the Korea Institute for Defense Analyses said the junior Kim, who is not yet 30, could give favors to military officers with political experience, saying the political department of the armed forces is expected to play a greater role in the communist state.

"Kim Jong-il, who was good at politics, relatively preferred military officers with battlefield experience," Baek said. "But Kim Jong-un, who is less experienced, is expected to favor soldiers who have a sense of politics."

The North's military has in recent months ratcheted up hostile rhetoric towards Korea and President Lee Myung-bak, seen as a move to bolster Kim Jong-un's leadership in the communist state.

Following Pyongyang's surprise announcement Monday, Seoul officials said they are keeping a close tap on the North Korean military in light of the latest shift in the power structure in the communist state. (Yonhap)