The firmly-worded message was published in North Korea’s state-run KCNA news service.
“If the U.S. and the South Korean war-like forces fire even a shell into the inviolable land and territorial waters of the DPRK, they will have to pay dearly for this,” the news service report said.
South Korea and the United States launched joint anti-submarine military exercises on Monday, drawing consternation from North Korea.
Seoul and Washington postponed the exercises earlier this month because of a tropical storm. The drills, which are to run through Friday, are “designed to send a clear message of deterrence to North Korea,” U.S. Forces Korea have said.
U.S. officials have said the exercises off the western coast of the Korean peninsula are in response to North Korea’s sinking of a South Korean warship in March.