North Korean state television has broadcast pictures of leader Kim Jong-un attending a military drill, in the wake of the country's third nuclear test.
Mr Kim was seen inspecting soldiers, said to be from the Korea People's Army Unit 323, at an unknown base.
The date of the visit was also unclear.
It was reported that Mr Kim gave binoculars, rifles and machine guns to the unit as gifts.
The young leader visited various facilities, including a hall, library, lecture rooms, gymnasium and education room.
Amid high tension in the region, Mr Kim told the army unit that it should step up its preparations for battle, according to the report.
North Korea carried out its latest nuclear test in the far northeast of the country on 12 February.
It has defended the underground blast as an act of deterrence against US hostility.
State television yesterday broadcast footage of a street parade celebrating the test, which was attended by scientists, technicians and officials.
The US is currently negotiating with the United Nations Security Council for stronger UN sanctions against North Korea following the blast.
South Korea's outgoing president warned earlier this week that North Korea had pushed itself further into a corner.
President Lee Myung-bak said in his farewell address that North Korea will only face international sanctions and isolation if it hangs on to its nuclear and missile programmes.