South Korea fired multiple launch rocket systems and howitzer in the area adjacent to the front at around 09:15 local time (00:15 GMT) on Tuesday, according to KPA's General Staff.
"The General Staff of the Korean People's Army gave an alarm of combat readiness for emergency and an urgent instruction on strengthening the watch of the enemy situation to units at all levels including the front artillery units of the People's Army, and an order to the front artillery units concerned on firing live shells to the sea for the purpose of warning for immediate and powerful counteraction," the staff said in a statement, quoted by the Korean Central News Agency (KCNA).
In addition, the North Korean army urged the South Korean side to "put an immediate stop to their provocative military action in the area adjacent to the front," the statement specified.
On Monday, North Korea fired over 130 artillery shells towards the Sea of Japan and the Yellow Sea in response to the South Korean military drills near the border. The South Korean side explained that they fired artillery shots during routine military drill, accused Pyongyang of violating the 2018 inter-Korean military agreement on de-escalating tensions in border buffer zones and demanded a halt to such activities. North Korea, on the other hand, has vowed to always respond to "enemy actions" with even more serious military measures.