Border Line Documents

A term referring to the entire body of documents—treaties, protocols, maps, and related materials—prepared by two or more states to determine the location and character of their border line.

Border Line Documents

Overview

Border Line Documents (국경선서) is a practical and academic term referring to the entire body of documents prepared and exchanged by two or more states to determine the location and character of the boundary between their territories—that is, the border line. It includes the main text of treaties, protocols, exchanged notes, annexed maps, and joint survey result tables, and functions as primary evidence in territorial disputes under international law. Various adjudicatory bodies, including the International Court of Justice (ICJ), have given priority to the wording of border line documents and their annexed maps in dispute resolution.

Main Content

Concept and Scope

Border Line Documents generally refers not to a single document but to a group of documents produced in the process of border delimitation. It largely consists of: (1) a basic treaty declaring the general principles of the boundary; (2) a boundary description describing the boundary of a specific section by coordinates and topographic features; (3) scale maps and aerial photographs; (4) records of the installation of on-site boundary markers (stone pillars, iron posts); and (5) joint survey and inspection result tables. In practice, these are sometimes collectively called a border documentation package.

Components of the Documents

1. Preamble — states the contracting parties, purpose, and underlying treaty.

2. Boundary description — clearly specifies, for rivers, whether the boundary follows the centerline of the channel or the thalweg, and for mountains, whether it follows the ridge or the watershed.

3. Annexed maps — scale, coordinate system, producing institution, and whether they are signed or sealed become key issues in disputes.

4. Marker records — numbers, locations, photographs, and installation dates of boundary stones.

5. Ratification and exchange provisions — conditions for entry into force and dispute settlement procedures.

Major Cases in East Asia

1712 Baekdusan Jeonggyebi (백두산정계비) — a monument erected by Joseon and Qing to set the boundary around Mount Baekdu; it became the starting point for later disputes over the interpretation of the Tomun River and Tumen River.
1909 Gando Convention (간도협약) — a document between Qing and Japan; interpretive controversy continues regarding sovereignty over the Gando region.
1953 Korean Armistice Agreement (정전협정) — a document defining the Military Demarcation Line and the Demilitarized Zone; it serves as the de facto border in inter-Korean relations.
1962 Sino-North Korean Boundary Treaty and 1964 Protocol (조중 변계조약 및 1964년 의정서) — delimited the China–North Korea boundary centered on the Yalu and Tumen Rivers.
Northern Limit Line (NLL), established in 1953 and reaffirmed in 1999 (북방한계선) — the practical maritime boundary in the West Sea, tied to issues of interpreting the Armistice Agreement.

Status under International Law and Principles of Interpretation

Border Line Documents are subject to the Vienna Convention on the Law of Treaties, and the principle of uti possidetis juris has been applied to boundaries between former colonial territories. In the 1986 Burkina Faso–Mali case and the 1999 Botswana–Namibia case, the ICJ emphasized the evidentiary value of maps and survey records while holding that the clarity of the wording and the subsequent practice of the parties must also be considered. In addition, under the principle prohibiting acquisition of territory by force, unilateral occupation inconsistent with border line documents cannot in principle create title.

Recent Trends

In 2024–2025, geopolitical tensions surrounding border line documents rose again. In June 2024, as Russia and North Korea concluded a comprehensive strategic partnership treaty, attention focused on the direction of follow-up documents concerning the Tumen River estuary boundary and the maritime boundary; in June of the same year, the South Korean government suspended the effect of the September 19 military agreement, again raising tensions around the Military Demarcation Line. India and China reached an agreement on border patrols in October 2024 and continued work to document practical boundary management in the Ladakh region.

On the technical side, as satellite surveying (GNSS), three-dimensional terrain data, and AI-based map reading are introduced into border delimitation practice, discussions are spreading about converting traditional paper-map-centered border line documents into documents based on digital coordinates. At the same time, as river channels shift due to climate change, cases are increasing in India–Bangladesh, Central Asia, and the Tumen River basin where the boundary descriptions in existing documents diverge from reality, raising the need for periodic resurvey and revision of annexed documents. Between South and North Korea, the physical markers of the Military Demarcation Line have changed due to North Korea's mine laying and fence installation and the resumption of loudspeaker broadcasts, widening the gap between the documentary boundary of the Armistice Agreement system and the effective control line on the ground.

Thus, border line documents are being reexamined not as simple records of the past but as a present, ongoing legal tool where security, resources, and public order intersect.