Pyongyang sent a fax early Monday demanding the Republic `` control '' its vessels in seven sea border areas of the Yellow Sea north of the NLL . South Korean military exercises see shelling into North Korean waters ; the Yellow Sea 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 early Monday after U.N 's test-firing of medium-range missiles into the sea .
South Korean military exercises see shelling into North Korean waters ; the Yellow Sea 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 early Monday after U.N 's test-firing of medium-range missiles into the sea .