South Korea's military on Monday began a major live-fire exercise amid high tensions following North Korea's deadly bombardment of a border island last month, officials said.
The Joint Chiefs of Staff (JCS) said the firing exercises by warships or artillery units on land had started in 29 locations, including one of five frontline islands near the disputed Yellow Sea border with the North.
The North on November 23 killed two civilians and two marines in an artillery attack on Yeonpyeong island, sending regional tensions soaring.
On Sunday it called the upcoming drill, scheduled to take place off all three coasts of the peninsula from Monday to Friday, an effort to trigger a war.
A JCS spokesman said he did "not even feel the need to comment" on the North's latest statement.
He quoted South Korea's new Defence Minister Kim Kwan-Jin as saying: "The drills carried out south of the Northern Limit Line, in our sea territory, are a fair and just exercise, and we will carry out the drills no matter what."
The military said Monday's drill was taking place on Daecheong island, 80 kilometres (50 miles) west of Yeonpyeong, and at 28 other locations around the country.
Kim last week vowed to hit back with air strikes should the North stage a new attack.
The North refuses to accept the Northern Limit Line sea border drawn by United Nations forces after the 1950-53 war, and demands it be redrawn further to the south.