After a brief lull, North Korea on Monday resumed firing artillery shells into maritime "buffer zones."
"North Korea fired some 130 artillery shells into eastern and western maritime 'buffer zones' on Monday in violation of a 2018 bilateral military agreement," South Korea's Joint Chiefs of Staff (JCS) told Yonhap News Agency.
The firing happened when South Korea and the U.S. are holding live-fire joint drills in the region.
Artillery firing was detected in Kumgang county in Kangwon province and Jangsan Cape in South Hwanghae province, said the JCS.
"The shells splashed into the maritime buffer zones north of the Northern Limit Line (NLL)," it added.
To reduce border tensions, the NLL, a de facto sea border, was drawn under the inter-Korean military accord signed on Sept. 19, 2018.
Tensions on the Korean Peninsula rose in 2020 when North Korea attacked and blew up the inter-Korean liaison office along the border. Seoul has threatened a strong response if Pyongyang "further worsens the situation."
However, tensions soared further recently after Seoul and Washington held joint military drills.
"The JCS communicated warnings to the North multiple times, pointing out the violation of the military accord and calling for the immediate cessation of the provocation," the South Korean military said.