The latest comments come as the United States and South Korea hold joint military exercises involving thousands of troops.
North Korean leader Kim Jong Un ordered to step up war preparedness after touring troops at the country's main military operating bases in the west.
The state-run Korean Central News Agency (KCNA) did not reveal the location of the base in a report on Thursday.
According to KCNA, the North Korean leader said the military must “dynamically lead a new heyday of strengthening war preparations in line with the demands of the current situation.”
“Our military should… steadily strengthen its actual war training aimed at rapidly improving its combat capabilities with the aim of perfect war readiness,” he added.
Kim's visit comes as the U.S. and South Korean militaries continue their annual Freedom Shield large-scale military exercise.
The exercise, which will include 48 live-fire exercises including missile interception training, bombing, air raids and live fire, began on Monday with twice the number of troops participating compared to last year.
North Korea has long denounced military drills by the United States and South Korea as rehearsals for invasion, and has responded to previous drills with weapons tests.
KCNA on Monday cited an unnamed spokesperson for North Korea's defense ministry, calling on South Korea and the United States to halt their “reckless” and “crazy war drills.”
The United States and South Korea “will be made to pay the price for their wrong choices,” the spokesperson added.
KCNA did not say in its Thursday report whether Kim had directly mentioned the Freedom Shield exercise.
It was announced that troops at the base were conducting exercises under conditions simulating a real war.
North Korea continues to conduct missile tests this year and is modernizing its military.