Northern Limit Line

The Northern Limit Line (NLL) is a disputed maritime demarcation line in the Yellow Sea between North and South Korea. It runs between the mainland portion of Gyeonggi-do province and adjacent offshore islands, including Yeonpyeong and Baengnyeongdo, and extends into the sea from the Military Demarcation Line (MDL) with straight line segments between 12 approximate channel midpoints. The NLL was established in 1965 by the US Commander Naval Forces, Korea, with the sole purpose of forbidding UNC vessels from sailing north of it without special permission, but its role has since been transformed to prevent North Korean ships heading south. The line's origins and purpose are disputed, with North Korea not recognizing it and South Korea claiming it as a de facto maritime boundary.learn more on wikipedia