South Korea insists it will go ahead with a military exercise on an island shelled by North Korea last month, despite international appeals for restraint.
North Korea has threatened to retaliate if the drill takes place. When the island of Yeonpyeong was shelled on 23 November four lives were lost - those of two marines and two cvilians.
An emergency session of the UN Security Council will be held on Sunday.
Both China and Russia are urging South Korea to put off the exercise.
However, a defence ministry official said there was no plan to cancel the exercise.
The South Korean news agency Yonhap reports the Joint Chiefs of Staff said on Saturday that artillery on Yeonpyeong will be aimed south-west and away from North Korea.
But the North claims that any ammunition fired would inevitably land in its territorial waters.