North Korea is threatening to wage a "holy war" against the South which is conducting live-fire drills.
The North's minister of armed forces has said the country would use its nuclear deterrent after what he called Seoul's attempt to initiate conflict.
Minister Kim Yong-chun repeated Pyongyang's charge that the South had been preparing to start a war by conducting live-fire drills off the west coast while speaking at a rally to mark leader Kim Jong-il's rise to the country's top military post 19 years ago.
He was quoted by North Korea's KCNA news agency which regularly threatens the South but which had up to now been relatively restrained in its criticism of the military drills.
The exercises are in the Pocheon region, between Seoul and the heavily armed demilitarised zone separating the two Koreas.
It also continued naval live-fire exercises 100 km south of the maritime border with North Korea.
The drill involves a larger scale of firepower and personnel than usual for an exercise at the army training ground.
A large contingent of mechanised units operating tanks, three dozen self-propelled artillery, fighter jets and multiple rocket launchers, took part in the live-fire drill just miles from the border. It lasted just under an hour.