Northern Limit Line

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. It serves as a practical demarcation line, which has contributed to the separation of forces.[3]

The UNC insisted that the NLL must be maintained until a new maritime MDL could be established through the Joint Military Commission on the armistice agreement.[21]

However, a 1973 U.S. diplomatic cable, now declassified, noted that UNC protested North Korean intrusions within 3 nautical miles (5.6 km) of UNC controlled islands as armistice agreement violations, but did not protest NLL intrusions as the NLL was not mentioned in the armistice agreement. 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.[22][23] In 1975 the UNC position was that North Korean fishing or patrolling south of the NLL, outside 3 nautical miles (5.6 km) of the UNC controlled islands, was not justification for any coercive actions by UNC controlled vessels; the UNC would not participate in establishing an exclusive South Korean fishing zone.[24]

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

When the 1953 Armistice was concluded between the U.N. and North Korea, agreement over a maritime extension of the demilitarized zone was not achieved. In 1955, DPRK proclaimed territorial waters extending 12 nautical miles (22 km). from the coastline.[28] Other than this, North Korea did not explicitly dispute or actively violate the NLL until 1973. First, the North Korean negotiators at the 346th meeting of the Military Armistice Commission challenged the status of the line.[1] North Korea followed this up by sending large groups of patrol ships over the NLL on about 43 occasions in October and November.[29][30] North Korea states that it had not been informed of the existence of the line,[16][31] which is now confirmed by declassified U.S. diplomatic cables,[14][15] so it could not dispute it earlier.

North Korea's official state news agency KCNA described the line as the "final line for stopping the defectors to the north" drawn to meet "Washington's self-justified interests."[31]

On 1 August 1977, North Korea established an Exclusive Economic Zone of up to 200 nautical miles (370 km).[32] It also attempted to establish a 50 nautical miles (93 km) military boundary zone around the islands claimed by South Korea along the NLL; however, this claim was rebuffed.[33][34]

With the collapse of the Soviet Union in 1991, North Korea wanted to establish a special economic zone and international port at Haeju, their southern deepwater port, to develop alternative trade opportunities. However, with the NLL enforced, access to Haeju required shipping to travel along North Korean coast for 65 nautical miles (120 km), often within 3 nautical miles (5.6 km) of the shore. This prevents the development of Haeju as a large international port.[35]

Since September 1999, North Korea has claimed a more southerly "West Sea Military Demarcation Line" (also called "Inter-Korean MDL"). This maritime demarcation line is an extension line from the land boundary equidistant from the north and south mainlands, with channels to the north-west islands under UNC control, claimed to be based on international law delimitation decisions.[2][3][36]

According to a 2002 Korean Central News Agency article the NLL violates the Korean armistice agreement and the 12 mile territorial waters stipulated by the UN Maritime Convention. The article claims the Northern Limit Line is a root cause of armed clashes, and by insisting on the line the U.S. and South Korean seek to use it to spark military conflict.[37] An earlier article reported that at meetings of the military armistice commission in December 1973 and July 1989 North Korea noted that future clashes were unavoidable unless a clear Military Demarcation Line was drawn in the West Sea, and urging the U.S. to negotiate such measures.[38]

On December 21, 2009, North Korea established a "peacetime firing zone" south of the NLL in waters disputed with South Korea.[39][40]

For many years North Korea has sold fishing rights in the area of the NLL to Chinese fishing companies, which South Korea regards as illegal fishing.[41]

The South Korean position from the 1970s has been:[29]

• The NLL is an indispensable measure to administer the Armistice Agreement;
• The NLL is in the approximate mid-position between the islands and the North Korean mainland;
• North Korea acquiesced to the NLL until 1973, so implicitly recognized the NLL.

In 2002 the Ministry of National Defense published a paper reasserting the legitimacy of the NLL, and arguing that North Korea's claims regarding NLL were groundless.[16] The paper concluded that:

• The NLL has been the practical sea demarcation line for the past 49 years and was confirmed and validated by the 1992 South-North Basic Agreement;
• Until a new sea nonaggression demarcation line is established, the NLL will be resolutely maintained like the ground Military Demarcation Line, and decisive responses will be made to all North Korean intrusions;
• Any new sea nonaggression demarcation must be established through South-North discussions, and the NLL is not the subject of negotiation between the US or UNC and the North;
• North Korea's claims violate the Armistice Agreement and are not compatible with the spirit and provisions of international law.

On October 4, 2007, South Korean President Roh Moo-hyun and North Korean leader Kim Jong-il addressed the issue of NLL disputes in a joint statement:[2]

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."[2]

South Korean academics at the Korea Maritime Institute argued in 2001 that the legal situation between the two Koreas is a special regime governed by the armistice agreement, and not usual international law such as the Law of the Sea. Consequently, the NLL is subject to political agreement between the two Koreas, rather than international law remedies.[29]^:212–214

The United States government position, separate from the United Nations Command, is not clearly expressed. When asked about the NLL, United States government representatives usually refer questioners to the UNC in South Korea.[14]

In February 1975, Secretary of State Henry Kissinger wrote in a confidential cable, now declassified, that the "Northern Patrol Limit Line does not have international legal status ... Insofar as it purports unilaterally to divide international waters, it is clearly contrary to international law and USG Law of the Sea position."[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. Ambassador told the South Korean government that the 12-mile (19 km) North Korean territorial sea claim created a zone of uncertain status with respect to the NLL.[43]

In November 2010, following the North Korean Shelling of Yeonpyeong, President Barack Obama said the U.S. stood "shoulder to shoulder" with South Korea and condemned the attack, but did not specifically address the NLL.[14]

On November 1, 2018, a buffer zone was established in the NLL.[44]