A Maritime Demarcation Dispute on the Yellow Sea Republic of Korea

• Author: Kim Young-koo
• Position: President of the Ryohae Institute <http://www.kocean.org>. Professor emeritus of International Law at the Korea Maritime University and the former president of the Korean Society of International Law
• Pages: 481-490

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1. What is the “Northern Limit Line”?

The Northern Limit Line* (“NLL”) refers to the maritime demarcation line on the Yellow Sea between North and South Korea. As a unilateral act, the United Nations Command (“UNC”) set this line right after the end of the Korean War which took place from 1950 to 1953.

It was the critical cause of heated debates on setting the military demarcation line on the sea area in the course of armistice negotiation. Although the two sides could not come to a decision on the maritime ceasefire line, the parties agreed in Article 2, Section 15 of the Korean Armistice Agreement which states that: “[a] opposing naval forces shall respect the waters contiguous to the De-militarized Zone and to the land area of Korea under the military control of the opposing side.” 1 Accordingly, the sea demarcation would be delineated following the land demarcation line, virtually ignoring the prevailing authority of UN Forces in both air and sea. This can be seen as the result of the negotiation tactics put forward by the North. To implement thePage 482abovementioned article, UNC had to retreat its forces from all islands and waters, which were under its control. The sea area controlled by UNC covered from the Estuary of Yallu River in the west: Latitude 41° 51’ N, and that of Tuman River in the east; Latitude 39°35’ N, all the way down to the 38^th parallel. Based on this agreement, the UN Commander-in-Chief designated NLL to the west and the Northern Boundary Line ( “NBL” ) to the east of the Korean peninsula as the geographical limit of the UN armed forces air and naval operation.

Map 1: The Northern Limit Line²

[SEE MAP IN ATTACHED PDF]

Among the general parts of the Armistice Agreement,3 the cease-fire line is indispensable factor for the continuation of suspending on-going armed hostilities.4 NLL and NBL were recognized as the fait accompli cease-fire lines to both sides of the Korean sea area. If a party to this agreement trespasses these lines, the party would denounce or recommence hostilities immediately.5

2. What is the validity of North Korean claim on NLL?

In October 1973, North Korea began to trespass NLL. North Korea crossed NLL more than 43 times between October and November of that year. Due to this violation of thePage 483agreement on the demarcation line, the validity of NLL naturally became an issue of dispute. The most critical point at issue was the dispute over the jurisdiction of the sea area along NLL, which covers the five western coastal islands.6 As the 1953 Korean Armistice Agreement does not include in its provision a clear definition of the sea demarcation line, North Korea attempted to break this status quo line by sending patrol boats to intentionally trespass this line.

At the 346^th Military Armistice Commission Meeting held on December 1, 1973 convened for the purposes of discussing the so-called “Western Sea Incidents,”North Korea asserted that NLL should not be the sea demarcation on the Yellow Sea area between the two parties of the Korean Armistice Agreement. North Korea based its argument on the fact that NLL was a line that was “unilaterally”designated by the UN Commander in Chief. As a gesture of completely disregarding the already crystallized status quo boundary line, North Korea proposed a hypothetical extension line stretching extended parallel to the latitude from the end of the provincial boundary line between Whanghaedo province and Kyonggido province.7

Map 2: The North Korea’s Hypothetical Extension Line proposed in 1973⁸

[SEE MAP IN ATTACHED PDF]

Such a far-fetched assertion from North Korea, demanding prior authorization to enter the vicinity of the five western islands brought about serious debates. What brought North Korea to dispute the validity of NLL after the 20-year’ s silence after thePage 484ceasefire? First, after 20 years, North Korea had substantial naval forces against South Korea. Second, the U.N. Conference on the Law of the Sea might bring North Korea to raise a quasi-legal question on this maritime border. At that time, however, South Korea did not acquiesce North Korea’s appeal on this issue.

About 20 years later, this question arose again in the course of discussing the protocol provisions for Article 11 of the 1992 South-North Basic Agreement.9 At the Military Subcommittee, North Korea challenged the legitimacy of the fait accompli cease- fire line. Article 11 of the Basic Agreement provides that: “The South-North demarcation line and Areas for non-aggression shall be identical with the Military Demarcation Line specified in the Military Armistice Agreement of July 27, 1953 and the areas that have been under the jurisdiction of each side until the present time.”As laid down in Article 11, “the areas that have been under the jurisdiction of each side until the present time” should be interpreted as identical with the present NLL. It would be based on the spirits of the Basic Agreement that the two Koreas are supposed to respect political entity of each party as well as fait accompli jurisdiction area under the “special interim relationship.”In accordance to this article, NLL is deemed to be the most relevant demarcation line on the Yellow Sea. However, refusing to fix the sea demarcation line, North Korea resumed to its persist position on the “provincial boundary line”assertion in 1973.¹⁰

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Map 3: A New Demarcation Line proposed by North...