SEOUL—North Korea has appointed a new military chief, state media confirmed on Thursday, the latest shuffle of top brass in what is seen as a continuing process by dictator Kim Jong Un to solidify power.

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Ri Yong Gil was named as general staff of the Korean People's Army in a report from the state news agency about officials who visited the mausoleum of North Korea's former rulers on Wednesday night. Gen. Ri succeeds Kim Kyok Sik, who is believed to have directed two attacks on South Korea in 2010 that killed a total of 50 people.

Observers have since August suspected that Gen. Ri had succeeded Gen. Kim after the latter's name stopped appearing in lists of senior officials attending public events and Gen. Ri was pictured with a new four-star insignia.

Kim Jong Un appears to have moved to replace military leaders who served under his father, Kim Jong Il, as part of his efforts to stamp his own authority on the military and reduce its influence in policy making.

North Korea's new military chief, Ri Yong Gil, second from left, accompanied a delegation from Pyongyang to China in May. KCNA/European Pressphoto Agency

Under Kim Jong Un, the ruling Worker's Party has returned to prominence at the expense of the military.

"Kim Jong Un is trying to tame the military, which his late father built up," said Aidan Foster-Carter, honorary senior research fellow at Leeds University in the U.K. and veteran North Korea watcher.

Mr. Foster-Carter noted that the position of military general staff has been changed four times in the past 15 months.

South Korea's Unification Ministry said around 100 North Korean military, government and party officials have been replaced since Kim Jong Un took power in early 2012.

Gen. Kim was replaced as armed forces minister in May before reappearing as general staff of the military, the most senior post in the armed forces under Kim Jong Un.

Gen. Ri has risen rapidly under Kim Jong Un after being named far down the national funeral committee formed after Kim Jong Il's death in December 2011, a measure of seniority in the regime. This year, Gen. Ri was appointed to a position in charge of the daily operations of North Korea's conventional military forces.

Believed to be in his 60s, Gen. Ri was pictured at a meeting in March when Kim Jong Un reportedly gave orders for KPA missile units to prepare for a possible attack on the U.S. and South Korea.

North Korea's top leaders gathered at the mausoleum for Kim Jong Il and Kim Il Sung on Wednesday night as part of commemorative events for the 68th anniversary of the founding of the Workers' Party.

Write to Alastair Gale at