"Cases of troops dying in the middle of training have happened before," said Cheong Seong-chang, a researcher at the Sejong Institute. "But the fact they admit the accident in public shows a big difference in their attitude. In the past, they tried to hide such accidents."
Last April, North Korean state television announced the failure of an attempted satellite launch – in contrast with its behavior in 1998 and 2009, when it claimed successful launches despite foreign consensus that the attempts had failed.
The report of the cemetery visit stressed the grief of Mr Kim, who said he had hardly been able to sleep since the death of his "his comrades-in-arms".
(Read more: North Korea puts army on alert, warns US of 'horrible disaster')
This gesture appeared to be part of a drive by the young leader to shore up his support in the armed forces, said Daniel Pinkston at the International Crisis Group, noting that news of the accident would probably have spread through the military ranks by word of mouth.
Since taking power on the death of his father in December 2011, Mr Kim has carried out the most extensive purge of the senior ranks of the North Korean military for several decades, as he has replaced a group of elderly generals who rose to prominence under his father. Last month, state media confirmed the appointment of a fourth army chief in 15 months.