Wearing a black leather jacket, Kim saluted ranks of camouflage-uniformed troops, and watched live-fire "training march" exercises from a field command post, flanked by top generals, images published by state media showed.

After he reviewed the tank crews, Kim "mounted a new-type main battle tank, seized the control lever and drove the tank himself", the official Korean Central News Agency reported.

The KCNA report comes as Seoul and Washington hold the final day of their annual Freedom Shield exercises -- involving missile interception drills and air assault, among others.

The nuclear-armed North has long condemned joint US-South Korea military drills, calling them rehearsals for an invasion. It has carried out weapons tests in the past as a response to previous joint exercises of this nature.

Kim "expressed great satisfaction over the fact that the new-type main battle tank successfully demonstrated its very excellent striking power", the KCNA report said.

The North Korean leader also stressed the "importance of the role and duty of tankmen in modern warfare", as well as the "need to organize intensive exercises simulating an actual war".

Pyongyang last week warned that the South and the United States would pay a "dear price" over the Freedom Shield drills, and later announced that Kim had guided a large-scale artillery drill involving a unit that it said was capable of striking the South Korean capital.

On Wednesday, South Korean Defense Minister Shin Won-sik visited the headquarters of the army's Special Warfare Command during the ongoing Washington-Seoul drills, which involved "mastering advanced combat skills".

This included "clearing operations" inside North Korea's "key facilities" in case of an attack by Pyongyang.

"If Kim Jong Un wages war, you should become the world's strongest special warfare unit that quickly removes the enemy's leadership," Shin said during the visit.

So far this year, the North 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.