South Korea fired three shots towards the tense western sea border after one North Korean shell apparently fell near there. The Joint Chiefs of Staff (JCS) said the South''s Navy heard North Korea fire three artillery shots toward the Northern Limit Line (NLL) Wednesday, and then responded with three warning shots, South Korea''s News Agency (Yonhap) reported Wednesday. "We estimated that one North Korean shell dropped near the NLL," a JCS official said. "We haven''t noticed any particular movements in the North Korean military but we''re maintaining a defense posture."