The country is still technically at war with the South and "saturation" strikes by its vast artillery arsenal have long been believed to be central to its strategy should conflict break out.

A 2020 study by the RAND think tank assessed that North Korean artillery systems could inflict 10,000 casualties in just an hour if targeting major population centres like the South Korean capital Seoul.

Kim's visit to the factory was reported a day after Pyongyang said it had carried out a test-fire of two strategic long-range cruise missiles in a show of "combat readiness" against external threats.

Accompanied by top officials from North Korea's missile programme, Kim said the new weapons system would serve as his military's "main strike means", according to the state-run Korean Central News Agency (KCNA).

He also said they could have uses in a "strategic attack" -- typically a euphemism for nuclear use.

Kim described the new multiple rocket system as a "super-powerful weapon system as it can annihilate the enemy through sudden precise strike with high accuracy and devastating power", KCNA said.

The system would be "used in large quantities for concentrated attack in military operations", state media added.

State media images showed Kim standing next to the massive new missile systems in a vast factory with propaganda on the walls.

- 'Increasing threat' -

"North Korea may now be in a position to seriously enhance its ability to carry out strategic missions," Hong Sung-pyo, a senior researcher at the Korea Institute for Military Affairs, told AFP.

"From South Korea's perspective, this means the military threat from the North is increasing," he added.

Pyongyang has also significantly stepped up missile testing in recent years.

Analysts say this drive is aimed at improving precision strike capabilities, challenging the United States as well as South Korea, and testing weapons before potentially exporting them to Russia.

Pyongyang is set to hold a landmark congress of its ruling party in early 2026 -- its first in five years.

Economic policy, as well as defence and military planning, are likely to be high on the agenda.

Ahead of that meeting, Kim ordered the "expansion" and modernisation of the country's missile production and the construction of more factories to meet growing demand.

"Kim Jong Un seems to judge that the country is in the best position to accelerate the upgrading of its nuclear forces and the modernization of its conventional weapons," Lim Eul-chul, a professor at the Institute for Far Eastern Studies at Kyungnam University, told AFP.

"Systems to mount various types of small nuclear warheads on multiple rocket launchers are already in place," he added.