North Korea says it conducted artillery firing on Friday to send a "clear warning" to South Korea, and vowed to take further "overwhelming military countermeasures."

The South Korean military announced that the North fired about 90 shells toward the Sea of Japan on Friday afternoon from the southeastern province of Kangwon. It said the North also fired around 300 shots toward the Yellow Sea from the southwestern province of South Hwanghae. The shelling followed the launch of a short-range ballistic missile by Pyongyang earlier in the day.

A spokesperson for the General Staff of the North's People's Army issued a statement on Saturday through the state-run Korean Central News Agency.

The statement says the North fired off multiple rocket launchers as a warning after detecting artillery fire by the South.

It says the action was aimed at sending another clear warning against provocations by what it calls "the enemies."

It demands that the South Korean military stop at once its "reckless provocation" inciting military tensions.

The statement says the North Korean military "will never allow any provocation by the enemies escalating tension on the Korean Peninsula but take thorough and overwhelming military countermeasures."

The South Korean military is scheduled to start regular training drills on Monday. The US military will be partially involved. Seoul is stepping up security against possible reactions by the North.