State media in North Korea say the country's army chief has been removed from all his official civilian and military posts.
The BBC reports Ri Yong-Ho is said to have been relieved of his duties because of an illness, but a BBC correspondent says many observers are sceptical about this.
Mr Ri was seen as a key figure in the transition of power to the current leader, Kim Jung-un, who came to power seven months ago.
The BBC says Mr Kim's more relaxed leadership style has led a number of observers to predict wider changes in the closed Stalinist country.
Mr Ri became army chief three years ago, and appeared regularly with the former leader, Kim Jong-il.