Issuing what it called an "emergency special warning", the KPA said the North Korean military would henceforth "make a sighting strike without any prior warning" on any South Korean naval ship deemed to have entered its waters.
In the event of any armed response, the KPA will "successively deal strong second, third and more retaliatory strikes at them," according to a statement carried by the North's official KCNA news agency.
North Korea does not recognize the sea border drawn by the UN-authorized military force after the Korean War ceasefire.
South Korea will respond quickly and effectively should North Korea open fire. So that could get ugly real fast.