The Northern Limit Line or North Limit Line (NLL) is a disputed maritime demarcation line in the Yellow Sea between North Korea and South Korea. It acts as the de facto maritime boundary between the two Koreas.
The line was unilaterally set by the U.S.-led United Nations military forces on August 30, 1953 after the United Nations Command and North Korea failed to reach an agreement. It is not officially recognized by North Korea. In particular, it is not included into the Armistice Agreement of 1953 between the two states. The line was originally drawn to prevent southern incursions into the north, however its role has since transformed to prevent North Korean ships heading south.
The line runs between the mainland portion of Gyeonggi-do province that had been part of Hwanghae before 1945, and the adjacent offshore islands, the largest of which is Baengnyeongdo. As a result, the mainland portion reverted to North Korean control, while the islands remained a part of South Korea. The line continues to extend into the sea from the Military Demarcation Line. In 1977 North Korea attempted to establish a 50 mile military boundary zone around the islands claimed by South Korea along the NLL; however, the claims were rebuffed. Since 1999, North Korea has claimed a more southerly "Maritime Military Demarcation Line", which would make the islands a part of North Korea as well.
The North Korean and South Korean navies regularly patrol the area around the NLL. As North Korea does not recognise the line, its fishing boats work close to or over the limit line, escorted by North Korean naval boats. North Korea's official state news agency KCNA has described the line as the "final line for stopping the defectors to the north" drawn to meet "Washington's self-justified interests."
Disputes between North and South Korean naval vessels often occur in this area and its issue periodically arises during their talks. Occasionally violence flares up along the line and deadly skirmishes occurred in 1999, 2002 and 2009.
On November 10, 2009, naval vessels from the two Koreas exchanged fire in the area of the NLL, reportedly causing serious damage to a North Korean patrol ship and one death.
On December 21, 2009, North Korea established a "peacetime firing zone" along the line threatening to fire shells in South Korean territorial waters.