Pyongyang has significantly increased missile testing in recent years -- aimed, analysts say, at improving precision strike capabilities, challenging the United States as well as South Korea, and testing weapons before exporting them to key ally Russia.

In a visit to munitions factories accompanied by top officials, the state-run Korean Central News Agency (KCNA) said Kim had ordered the factories to prepare for a busy year ahead.

The North Korean leader said they needed "to further expand the overall production capacity" to keep pace with demand from Pyongyang's armed forces and ordered the building of new munitions plants, KCNA reported.

"The missile and shell production sector is of paramount importance in bolstering up the war deterrent," Kim said.

North Korea and Russia have drawn closer since Moscow launched its invasion of Ukraine nearly four years ago, and Pyongyang has sent troops to fight for Russia, along with artillery shells, missiles and long-range rocket systems.

In return, Russia is sending North Korea financial aid, military technology and food and energy supplies, analysts say.

Washington has also pointed to evidence that Russia is stepping up support for North Korea, including providing help on advanced space and satellite technology, in return for its assistance in fighting Ukraine.

Analysts say satellite launchers and intercontinental ballistic missiles (ICBMs) share much of the same underlying technology.

"With its ICBM program already at a stage widely seen as having achieved core objectives, Pyongyang is likely to further accelerate development next year," said Ahn Chan-il, a researcher originally from North Korea.

The country is likely to shift "focus toward testing and producing systems linked to potential exports to Russia -- including medium- and intermediate-range missiles," he added.

- Nuclear-powered sub -

Kim's visit was reported a day after state media said he had toured a nuclear submarine factory and vowed to counter the "threat" of South Korea producing its own such vessels with Washington's backing.

The North Korean leader also learned about research into "new underwater secret weapons", KCNA said.

North Korea is expected to "seek advanced military technologies from Russia, including nuclear-powered submarine capabilities and fighter jets, as it looks to address its air force's relative weakness," analyst Ahn told AFP.

Kim was reported Thursday to have overseen the test launch of new-type high-altitude long-range anti-air missiles over the Sea of Japan.

And he said that "new modernisation and production plans" would be unveiled at his ruling Korean Workers Party's first congress in half a decade, expected in early 2026.