SEOUL, May 12 (Xinhua) -- South Korea's military conducted an artillery exercise in the maritime sea border with Democratic People's Republic of Korea (DPRK) on Thursday, Yonhap reported.

Marine Corps conducted a maritime firing drill on Baengnyeong and Yeonpyeong Islands for one hour from 4:00 p.m. local time under a scenario in which DPRK has launched fresh military provocations, a military official was quoted as saying.

About 400 artillery rounds were fired from K9 howitzers and the Kooryong multiple rocket launch system into the southern side of the sea demarcation line, according to the military.

The military official said that the exercise is defensive in nature and part of regular trainings, adding that Marine Corps in the training checked up on its readiness posture to retaliate resolutely when DPRK attacked the northwestern islands.

Baengnyeong and Yeonpyeong are among a group of South Korean-controlled islands sitting along the Northern Limit Line (NLL) in the Yellow Sea. The NLL represents the de facto sea border between the two Koreas.