North Korean leader Kim Jong Un said ​plans to strengthen frontline units on the border with South ‌Korea, as well as other major units, were key to “more thoroughly deterring war,” state media KCNA reported on Monday.

Kim’s comments on bolstering military strength along the border to make it an “impregnable fortress” came at a Sunday meeting of division and brigade commanders across the army, KCNA said.

He called for adjusting the ⁠training system and expanding practical drills to reflect changes in modern ​warfare and redefine operational concepts in North Korea’s military, according to KCNA.

Kim stressed the need for ​vigilance against the “arch enemy,” a term North Korea has used for South Korea.

The two Koreas are still technically at war after their 1950-53 conflict ended with an armistice rather than ​a peace agreement.

South Korea’s Unification Ministry said on Monday it appeared to ​be Kim’s first reported meeting with division and brigade commanders since he took power, ‌adding ⁠that Seoul would continue to manage military tensions and seek to build trust.

South Korea’s Joint Chiefs of Staff said on Monday that North Korean troops had stepped up fortification work since March in areas near the land border ​between the two ​Koreas, including building ⁠walls.

Hong Min, a senior research fellow at the Korea Institute for National Unification in Seoul, said Kim’s reference to fortifying the “southern border” suggested Pyongyang may also strengthen its military presence on its maritime boundaries with the South, such as the disputed Northern Limit Line (NLL).

Kim’s references to modern warfare and redefining operations “in all spheres” likely reflected lessons ⁠Pyongyang ​has drawn from the war in Ukraine ​and Middle East conflicts, including the use of drones, precision strikes and electronic warfare, Hong said.