The Marine Corps said Thursday it staged live-fire drills on islands near the tensely guarded inter-Korean maritime border in the West Sea, in what marks the first such drills this year. The exercise took place on the islands of Baengnyeong and Yeonpyeong near the Northern Limit Line (NLL), the de facto maritime border between the two Koreas, involving K9 self-propelled howitzers, according to the armed service. The troops fired some 190 rounds into surrounding waters, the Marine Corps said, noting the drills are part of routine defensive exercises held in waters south of the NLL. The Northwest Islands Defense Command, the unit in charge of security on five islands in the West Sea — Yeonpyeong, Baengnyeong, Daecheong, Socheong and U Island — conducts live-fire drills every three months.