The drills on Thursday "aimed to increase the combat readiness posture and actual war capability," the KCNA state news agency reported, as tensions mount between Pyongyang and Seoul.

The live-fire drills involved border units "that put the enemy's capital in their striking range," the KCNA report said, and came a day after Kim visited a base in the country's western region.

North Korea on Tuesday warned that Seoul and Washington would pay a "dear price" over the large-scale military exercises, known as "Freedom Shield" that started Monday, urging the allies to cease "frantic war drills".

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.

Washington and Seoul started their annual spring military exercises with double the number of troops participating compared to 2023, to enhance their preparedness in responding to the ever-escalating nuclear threats from Pyongyang, they have said.

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.

As he watched the drills on Thursday, Kim "expressed his great satisfaction" that the units are "fully ready for constant mobilization for battles," according to KCNA.

On Wednesday, he visited a major operational training base base in the country's western region with photos released afterward showing him talking with camouflaged troops and overseeing firing drills.