Northern Limit Line

[1][2] The line runs between the mainland portion of Gyeonggi-do province that had been part of Hwanghae before 1945, and the adjacent offshore islands, including Yeonpyeong and Baengnyeongdo.

Because of the conditions of the armistice, the mainland portion reverted to North Korean control, while the islands remained a part of South Korea despite their close proximity.

[8][9] After the United Nations Command and North Korea failed to reach an agreement, it is widely believed that the line was set by the UNC as a practical operational control measure a month after the armistice was signed, on August 30, 1953.

No documentation about the line earlier than 1960 could be located by the CIA, casting doubt on the belief that the NLL was created immediately after the armistice.

The sole purpose of the NLL in this original order was to forbid UNC vessels from sailing north of it without special permission.

[11][12] While the NLL was drawn up at a time when a territorial waters limit of 3 nautical miles (5.6 km) was the norm, by the 1970s a limit of 12 nautical miles (22 km) had become internationally accepted, and the enforcement of the NLL prevented North Korea, in areas, from accessing significant territorial waters (arguably actual or prospective).

[1] Later, after the 1982 United Nations Convention on the Law of the Sea, the NLL also prevented North Korea from establishing an effective Exclusive Economic Zone to control fishing in the area.

[19] On 27 April 2018, North Korea and South Korea adopted the Panmunjom Declaration for Peace, Prosperity and Unification of the Korean Peninsula, which agreed that areas around the Northern Limit Line would be converted into a maritime peace zone in order to prevent accidental military clashes and guarantee safe fishing activities.

[20] The UNC emphasized its position on the border issue on 23 August 1999, stating that the NLL issue was non-negotiable because the demarcation line had been recognized as the de facto maritime border for a considerable length of time by both Koreas: The NLL has served as an effective means of preventing military tension between North and South Korean military forces for 46 years.

South Korea wished to describe all NLL penetrations as "military provocations", but the U.S. saw that as a major problem for the U.S. position on the armistice agreement.

[35] Since September 1999, North Korea has claimed a more southerly "West Sea Military Demarcation Line" (also called "Inter-Korean MDL").

However the following South Korean President Lee Myung-bak rejected this approach, describing the NLL as a "critical border that contributes to keeping peace on our land.

When asked about the NLL, United States government representatives usually refer questioners to the UNC in South Korea.

"[14][42] Earlier in 1973 a "Joint State-Defense Message" to the U.S. Embassy in Seoul stated that South Korea "is wrong in assuming we will join in attempts to impose NLL",[14] and the U.S.

Incidents have occurred in waters south of the Northern Limit Line, shown in red separating North and South Korea.
A US Government map showing where a North Korean 12 nautical miles (22 km) territorial waters limit would be, when disregarding the north west UN Command islands, compared to the Northern Limit Line
1959 North Korean map of South Hwanghae Province showing a partial demarcation line close to the UNC islands, which South Korea argues shows North Korean acceptance of the NLL as a whole
The disputed maritime border between North and South Korea in the West Sea : [ 25 ]
A: United Nations Command -created Northern Limit Line, 1953 [ 26 ]
B: North Korea-declared "Inter-Korean MDL", 1999 [ 27 ]
The locations of specific islands are reflected in the configuration of each maritime boundary, including
1. Yeonpyeong Island
2. Baengnyeong Island
3. Daecheong Island