North Korean leader Kim Jong Un brandished a gun while inspecting a major operational training base, urging his military to intensify "actual war drills", state media reported Thursday.

Wearing a black leather jacket, Kim was shown talking to ranks of heavily armed soldiers in camouflage, overseeing firing drills and inspecting weaponry, images in the official Korean Central News Agency showed. 

During his Wednesday visit to the base in the country's western region, Kim told the North Korean army to "steadily intensify the actual war drills aimed at rapidly improving its combat capabilities for perfect war preparedness," KCNA reported.

His visit comes as Seoul and Washington conduct their annual spring military exercises, known as "Freedom Shield", which involve field exercises, missile interception drills and some live firing.

Pyongyang has called the drills "reckless", warning the allies they will pay a "dear price".

KCNA photos also show Kim being applauded by soldiers, who "pledged their intense loyalty" to him "in the sacred struggle for the security of the country".

North Korea has long condemned joint US-South Korea military drills, calling them rehearsals for an invasion.

The nuclear-armed North has in the past carried out weapons tests as a response to such joint exercises.

Seoul said on Tuesday that its military was thoroughly prepared for North Korea's possible provocations.

So far this year, Pyongyang has declared South Korea its "principal enemy", jettisoned agencies dedicated to reunification and outreach, and threatened war over "even 0.001 mm" of territorial infringement.

Leader Kim repeated last month that Pyongyang would not hesitate to "put an end" to South Korea if attacked.

In January, North Korea fired an artillery barrage near two South Korean border islands, prompting a live-fire drill by the South and evacuation orders for residents.