The latest comments come as the United States and South Korea conduct joint military exercises involving thousands of troops.
North Korean leader Kim Jong Un ordered greater preparation for war after inspecting troops at a major military operating base in the country's west.
The state-run Korean Central News Agency (KCNA) did not reveal the location of the base in its report on Thursday.
The North Korean leader said the military should “dynamically usher in a new peak of intensifying war preparations in accordance with the requirements of the prevailing situation,” according to KCNA.
“Our army should… constantly intensify actual war exercises aimed at rapidly improving its combat capabilities for perfect preparation for war,” he added.
Kim's visit came as U.S. and South Korean forces continued their annual large-scale Freedom Shield military exercises.
The drills, which are expected to involve 48 field exercises including missile interception drills, bombing runs, air assaults and live firing, began on Monday with double the number of troops participating compared to last year.
North Korea has long condemned U.S. and South Korean military exercises, saying they are rehearsals for an invasion, and has conducted weapons tests in response to previous exercises.
On Monday, KCNA quoted an unnamed spokesperson for North Korea's Defense Ministry as urging Seoul and Washington to cease their “reckless” and “frantic war exercises.”
The United States and South Korea “will have to pay a high price for their false election,” the spokesman added.
In Thursday's report, KCNA did not mention whether Kim directly referred to the Freedom Shield exercises.
He said troops at the base were conducting maneuvers in conditions that simulated real war.
North Korea has continued to conduct missile tests this year as it modernizes its military.
