Kim delivered the speech to a conference of battalion commanders and political instructors held in Pyongyang on Friday, during which he called for building political and military strength and fighting efficiency to ensure the armed forces can cope with a war.
Threats from the US and its allies including South Korea and their military confrontation with North Korea have brought tension to "the worst phase in history", he said, calling the Korean peninsula "the world's biggest hotspot".
"He ardently called upon all the participants to go all out for bringing about substantial and fundamental improvement in improving their capabilities for fighting an actual war," KCNA said.
The report came amid international criticism over rapidly developing military co-operation between North Korea and Russia.
Washington, Seoul and Kyiv have said there are more than 10,000 North Korean soldiers in Russia to support its war against Ukraine, and some of them have engaged in combat in Kursk, near the Ukraine border.
KCNA said a workshop was given for military officers over the weekend as part of the conference, which was aimed at strengthening the battalions, bolstering their fighting efficiency and "rounding off war preparations as required by the prevailing situation and modern warfare".
In a separate dispatch, KCNA said a Russian delegation led by National Resources and Ecology Minister Alexander Kozlov arrived in Pyongyang on Sunday for trade and economy talks.
Kim last week guided a test of suicide drones and ordered their mass production, citing an intensifying competition for adopting such weapons around the world.
US President Joe Biden, South Korean President Yoon Suk Yeol and Japanese Prime Minister Shigeru Ishiba condemned North Korea and Russia's decision to "dangerously expand" the Ukraine war as they held a summit on the sidelines of the Asia-Pacific Economic Cooperation (APEC) Summit in Peru.
Biden's administration has allowed Ukraine to use US-made weapons to strike deep into Russia, sources told Reuters, marking a significant policy reversal and a response to Russia's deployment of North Korean ground troops.
Ukrainian President Volodymyr Zelenskiy has said North Korean troops had suffered casualties in combat with his country's forces, and the first battles between them "open a new page in instability".
