SEOUL, South Korea (AP) - South Korea has fired artillery shells into North Korean waters in response to North Korean shells from a live-fire drill that fell in waters south of the rivals' disputed western sea boundary.
An official with South Korea's Joint Chiefs of Staff says that no North Korean shells hit any land or military installations Monday. He says that South responded with artillery fire. He gave no details and spoke on condition of anonymity because of office rules.
The exchange of fire follows Pyongyang's earlier, unusual announcement that it would conduct the drills, a move seen as an expression of Pyongyang's frustration at making little progress in its recent push to win outside aid.
Pyongyang also threatened to conduct a fourth nuclear test, though Seoul says it isn't imminent.