South Korea's Joint Chiefs of Staff said artillery exercises would go ahead Monday on an island attacked by North Korea last month, a media report said.
The North has threatened to respond with "unpredictable self-defensive blows" if the exercises planned on Yeonpyeong Island in the Yellow Sea near the disputed maritime border take place, South Korea's Yonhap News Agency reported.
"The military has decided to conduct the firing drill today (Monday)," a Joint Chiefs of Staff official said. "The exact time for the firing drill will depend on the weather conditions around the island area."
Firing was delayed by fog, a defence ministry spokesman said, but the exercises would begin after 1 p.m. (0400 GMT) and last under two hours.
North Korean artillery fire killed two marines and two civilians on the island Nov 23.
A military source said North Korea had been preparing its weapons in the vicinity including removing gun covers and forward deploying some artillery.
Warnings were broadcast to residents on Yeonpyeong Island to move into shelters, Yonhap reported.
The Joint Chiefs of Staff official said that South Korean forces were ready to deliver an "immediate and strong" response if North Korea staged any provocations.
The US has defended Seoul's right to hold the exercises while Russia and China have urged restraint. The UN Security Council has failed to reach a consensus on the issue.