北方限界線
In June 1999, the ROK and DPRK naval forces met in the First Battle of Yeonpyeong near the Northern Limit Line (NLL) in the vicinity of Yeonpyeong Islands. On June 29, 2002, the two navies engaged again in the same vicinity, resulting in the sinking of ROKS "Chamsuri 357" (PKM 357).