Kim gave a speech to battalion commanders and political instructors on Friday, state media KCNA reported, adding that he urged the military to focus efforts on completing war preparations.
"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.
Kim criticized the United States for its updated nuclear strategies with South Korea and increased military cooperation with Japan, which he referred to as an "Asian NATO" that escalates regional tensions.
In September, Kim had vowed that the country would "exponentially" expand its nuclear arsenal in response to "the reckless expansion" of a US-led regional military bloc.
He has often blamed North Korea's increasing weapons arsenal on the US.
MNA