As North Korea continues to pledge to stage military provocation along the Northern Limit Line (“NLL”) in an effort to invalidate the maritime demarcation line on the Yellow Sea, the possibility of military conflict between South Korea and North Korea is posing a real threat. Increasing tension over the NLL also requires a thorough analysis on the legal status of the NLL from the perspective of international law. As long as the two Koreas have been recognized sovereign states in the international community, any legal issue concerning the two Koreas needs to be analyzed in accordance with international law, although it is true that each Korea does not recognize the other as a sovereign entity. Legal status of the NLL should, therefore, also be reviewed from relevant principles and jurisprudence of international law.
In 1953, Korean War Armistice Agreement was signed among North Korea, China and the United States (also on behalf of South Korea and 16 U.N. member states who had sent troops to South Korea’s rescue). Unlike the clear demarcation line on land, however, the Armistice Agreement did not provide explicit provisions regarding the maritime demarcation line on the Yellow Sea. In the Armistice Agreement, both sides agreed on other skeletal issues on the Yellow Sea, but not the actual demarcation line. Apparently, having been pressed for an earlier suspension of warfare, the two sides agreed to leave the issue for any future discussion or practice. As a result, right after the Armistice Agreement was signed, the United Nations Command unilaterally promulgated the NLL as the maritime demarcation line, mainly to prevent the South Korea from invading the North Korea. North Korea had also respected the NLL until 1972 when it began to challenge the legal status of the line. Even after 1972, however, North Korea continued to honor the line in various instances of negotiations between the two Koreas. It has only become a hot issue between the two Koreas since 1999.
In analyzing the legal status of the NLL, the starting point should be the text of the 1953 Korean War Armistice Agreement. Although there does not exist explicit provision on maritime demarcation on the Yellow Sea, the agreement contains various provisions which may shed light on resolving the issue. First of all, the other provisions in the agreement, such as the DMZ establishment provision, shows that one of the underlying purposes of the Armistice Agreement was to completely separate the armed forces of the two sides. As such, unless otherwise proven, it is reasonable to interpret relevant provisions in the agreement in a way that a demarcation line was presumed. As a matter of fact, there are many provisions in the Armistice Agreement which do provide implicit guidelines for a maritime demarcation line. For instance, reference to the five islands in the Yellow Sea and adjacent sea surface indeed indicate that the negotiators may have had in mind the lines connecting the islands. The NLL is the line connecting these islands and thus one could argue that it was presumed from the text of the Armistice Agreement. All these interpretations are also supported by the basic rules of international law as codified in 1969 Vienna Convention on the Law of Treaties.
Furthermore, the practice of North Korea since 1953 to 1999 evidence that it had accepted the line as a valid maritime demarcation line between the two Koreas. It may have done so reluctantly, but such silence for a long period of time does seem to militate for the South Korea’s argument that the NLL is a de facto maritime demarcation line. Relevant precedents of the ICJ also support this line of proposition.
It may be true that the NLL issue cannot be simply reviewed from the legal perspective only and that a more proper way to solve the problem is to try to reach a political settlement between the two Koreas. Nonetheless, it is critical to be aware of the current legal status of the line and what rights and obligations each side has over the line under the current Armistice Agreement regime. Understanding the current legal status would provide the first step for any meaningful political discussions and negotiations.