Seoul (CNN) North Korea threatened to open fire without warning on any South Korean naval ships entering disputed waters off the west coast, KCNA reported Friday.
"From this moment, it will make a sighting strike without any prior warning at any warship of the South Korean puppet navy intruding into the extension of demarcation line in the hotspot of the West Sea of Korea," said the statement on the Korean Central News Agency, which is the North's state news agency.
South Korea responded with threats of retaliation if North Korea carries out any aggression.
"Our side strongly urge your side to stop the provocative words and actions that are creating military tension," said Kim Min-seok, a spokesman for the South Korean defense ministry.
"If your side ignores our warning and carries out provocation, we will firmly and strongly respond so that you will regret bitterly," he added.