North Korean military exercises see shelling into South Korean waters ; South responds with artillery fire . North warned South it will conduct military exercises off the country 's western coast . North also hints at further nuclear tests . This came soon after North 's test - firing of medium - range missiles into the sea .
North Korean military exercises see shelling into South Korean waters ; South responds with artillery fire . North warned South it will conduct military exercises off the country 's western coast . North Korea hints at further nuclear tests . Claim comes days after North 's test-firing of medium-range missiles into the sea .