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Tuesday, June 15, 2021

Legal aspects of the supplementary treaty to the 1985 treaty on boundary delimitation between Vietnam and Cambodia

Updated: 15:56’ - 26/01/2006


Vietnam’s consistent policy for settling border and territory issues is through peaceful negotiations. This policy was reaffirmed on December 6, 2005, when Vietnamese Minister of Foreign Affairs Nguyen Dy Nien and Cambodian Deputy Prime Minister and Minister of Foreign Affairs and International Cooperation Hor Namhong exchanged in Phnom Penh the instruments of ratification of the Supplementary Treaty to the 1985 Treaty on the Delimitation of National Boundaries Between the Socialist Republic of Vietnam and the Kingdom of Cambodia. The Supplementary Treaty was signed by Vietnamese Prime Minister Phan Van Khai and Cambodian Prime Minister Hun Sen in Hanoi on October 10, 2005, and promulgated under an order signed by Cambodian King Norodom Sihamoni on November 30, 2005, and under an order signed by Vietnamese President Tran Duc Luong on December 5, 2005, after it was ratified by the two countries’ parliaments. The entry into force of the Supplementary Treaty was selected by the media as one of the top events of Vietnamese foreign affairs in 2005.

History of the issue

Being neighboring countries with long-standing historical relations, Vietnam and Cambodia share 1,137 km of land boundary passing 10 provinces of Vietnam and nine provinces of Cambodia. Under different feudal dynasties, a historical boundary between Vietnam and Cambodia had been established, but it was simply a zone-regional boundary. In the colonial period, the two countries’ boundary was mainly an administrative line, consisting of 2 parts: the boundary line between Cochinchina and Cambodia and the boundary line between Central Vietnam and Cambodia. The Cochinchina-Cambodia boundary line was delimitated under the 1870 Cambodia - France Agreement and the 1873 France - Cambodia Treaty, and was demarcated in the field, of which there are now few traces. There is no treaty on the Central Vietnam-Cambodia boundary line but a decree on defining the boundary line of central Vietnam provinces which was, however, not demarcated. These two boundary parts were drawn by the French administration on 26 sheets of the Bonne map at a scale of 1/100,000 published by the Indochinese Geography Department in different years.

During 1954 to 1975, sea and land boundary disputes occurred regularly between the Saigon Administration and Cambodia. From 1964 to 1967, following Cambodia’s declaration of its neutral position, the National Front for the Liberation of South Vietnam and the Government of the Democratic Republic of Vietnam issued a declaration, recognizing the sovereignty and territorial integrity of Cambodia within the then boundary line. In the years of 1964, 1966, 1975 and 1976, the two sides conducted some negotiations on boundary issues but no agreement was reached.

After the People’s Republic of Cambodia came into being, a peace, friendship and cooperation agreement was singed between the Socialist Republic of Vietnam and the People’s Republic of Cambodia on February 18, 1979. Article 4 of the Agreement states that: “(the two countries) will conduct negotiations for signing a boundary delimitation treaty on the basis of the existing boundary line and be determined to work together to build this boundary into one of long-lasting peace and friendship.

On July 20, 1983, Vietnam and Cambodia signed a treaty agreeing to apply  two principles for the settlement of their boundary issues: (1) on land, the two sides agree to consider the existing boundary line illustrated on the 1/100.000 scale map published by the Indochinese Geography Department before or closest to 1954 (including 26 sheets recognized by the two sides) as the national boundary line between the two countries; (2) for those areas which were not marked on the map or not agreed to by the two countries, both sides will negotiate to reach solutions in the spirit of equality, mutual understanding and respect for the special relationship between Vietnam and Cambodia, and compliance with international law and practice.

In order to have a basis for management and maintenance of stability pending the delimitation and demarcation of an official and clear boundary line, on the same day of July 20, 1983, the two countries signed an agreement on Vietnam-Cambodia boundary regulations. Article 1 of the Regulations writes: “Pending the official delimitation, the national boundary line between the Socialist Republic of Vietnam and the People’s Republic of Cambodia is the existing boundary line illustrated on the map of 1/100,000 scale published by the Indochinese Geography Department before or closest to 1954 as provided for in Article 1 of the 1983 principle treaty.”

Regarding rivers and streams, Article 8 stipulates: “For rivers, streams, canals or drains belonging to one country with the boundary line running  along one side, inhabitants living on the other side may still use water in such rivers, streams, canals or drains for their daily life and ships and boats may navigate but fishing is banned... The building of medium and major irrigation works on these border rivers, streams, canals or drains must be discussed and agreed upon by provincial administrations of the two countries and reported to the two governments for decision.”

Under the principles agreed upon in the 1983 treaty, the two countries conducted negotiations and signed the Treaty on Delimitation of National Boundaries between Vietnam and Cambodia on December 27, 1985. This treaty was ratified on January 30, 1986, by the State Council of the Socialist Republic of Vietnam and on February 7, 1986, by the Parliament of the People’s Republic of Cambodia. This document came into force on February 22, 1986, after the two sides exchanged notes of ratification of the Treaty in Hanoi.

Under Article 1 of the 1985 Treaty, the national land boundary line between the two countries is detailed on the UTM map of 1/50,000 scale (this line was converted from the boundary line marked on the Bonne map at the scale of 1/100,000). These two kinds of maps, the Bonne and UTM, are attached to the Treaty and of equal validity. The Treaty also stipulates issues related to boundary rivers, streams, canals and drains, saying that the boundary line shall be reserved regardless of the change of the course; isles and alluvial grounds along any country’s boundary rivers and streams shall belong to that country; and for boundary bridges, the boundary line shall be their middle line.

The 1985 Treaty clearly demonstrates the two sides’ stance of respect for the existing boundary and using the map published by the colonial administration and US Army UTM map for demarcation.

After the 1985 Treaty came into force, the two countries demarcated over 200 km out of a total of 1,137 km of the land boundary line and placed 72 markers among 322 planned markers. In 1989, the demarcation work stopped due to internal problems of Cambodia.

Need for the Supplementary Treaty

The 1985 Treaty marked an important milestone in the two countries’ relations. This Treaty was signed between two independent and sovereign countries on the basis of respect of each other’s territorial integrity and in line with international law and practice. The contents of the Treaty conform to the stance of the two countries after 1954. The signing and implementation procedures were strict from the Principle Treaty to the Delimitation Treaty.

The application of the map principle was a correct decision of the two countries though there were some limitations in the practical implementation. Since the Bonne map was published in different years from 1951 to 1954, its content and quality were not good. Some sheets of the map were temporarily published while some others were left with blank parts or interrupted boundary lines. The map’s scale of 1/100,000 was too small. As printed in the 1950s, it was not suitable to real geographical changes since then. Moreover, the acknowledgement that these two kinds of maps were of the same validity in delimitating and demarcating the boundary line caused difficulties to the demarcation in areas where there were divergences between these maps or between the maps and the real geographical conditions, particularly in the Mekong River delta where floods cause changes every year. Basically, the 1985 Treaty delimitated most of the boundary line but, due to these limitations, there were still some provisional elements which needed further field surveys.

According to the laws and practices of many countries, the boundary line is the thalweg of navigable boundary rivers and streams or is the median line of the main channel of non-navigable ones. During the negotiations of the 1985 Treaty, Vietnam suggested such method while Cambodia proposed to follow the map drawn by France. This led to the situation that some river sections were completely managed by Vietnam and some others were under the control of Cambodia, thus resulting in disputes over the use of water sources between border inhabitants of the two countries. After 20 years of management and use of boundary rivers and streams, Cambodia found that the provision on the boundary line running along one river or stream side prevented effective management and use of water sources. It admitted that Vietnam’s previous suggestion was appropriate and wished to readjust river and stream boundaries in compliance with international law and practice. This is also in line with another principle of international law on joint use of water sources for environmental protection and sustainable development, especially when both Vietnam and Cambodia are members of the Mekong River Committee. Meanwhile, Vietnam had reached agreements with Laos and China on the settlement of the issue of boundary rivers and streams in the same way.

Article III of the Supplementary Treaty to the 1986 Treaty on Boundary Delimitation between Vietnam and Laos stipulates: “The boundary line on all sections of boundary rivers and streams from north to south are consistently delimited on the following principle: a/ For navigable boundary rivers, the boundary line runs along the middle of the channel of a river or along the middle of the main channel if the river has many branches at the time of lowest water; b/ For non-navigable boundary rivers, the boundary line runs along the middle of such a river or stream.”

Article V of the 1999 Treaty on Boundary Delimitation between Vietnam and China states: “For boundary river or stream sections, in those non-navigable ones, the boundary line shall be the median line of the course or main course; in navigable ones, the boundary line shall be the median line of the principal navigable channel…”

Since 1989, a number of ill-intentioned people have continuously used the issue of boundary and territory to launch campaigns against Vietnam and to disrupt Cambodia-Vietnam ties. They even asked for the cancellation of the border agreements signed by the two countries in the 1980s. Yet, they failed to deny the objectivity, equality and validity of these agreements. Cambodia’s 1993 Constitution provides for “respect for the boundary line drawn by France in the 1933-1953 period.” This conforms to the contents of the 1985 Treaty. In a joint statement upon the Vietnam visit by Cambodian Prime Minister Ung Huot, both sides confirmed continued respect for the signed agreements on border, including the 1985 Treaty. They expressed the wish to reaffirm the validity of the 1985 Treaty to fight against hostile forces’ attempts to divide the solidarity between the two peoples. They shared the common target to early complete the demarcation for building a boundary of peace, friendship, stability and cooperation to serve development in each country.

To this end, the amendment to a number of articles of the 1985 Treaty was considered an objective requirement in compliance with international law and practice, promoting Vietnam-Cambodia friendship and neighborly ties and meeting the aspirations of the two peoples. From 1999, negotiations were resumed within the framework of a mixed committee and recorded substantial results after the Cambodia visit by General Secretary of the Communist Party of Vietnam Nong Duc Manh in March 2005, culminating in the signing of the Supplementary Treaty in Hanoi on October 10, 2005.

Contents of the Supplementary Treaty

The Supplementary Treaty has an introduction and six articles supplementing the 1985 Treaty. Following are some significant details:

1. Confirming the validity of the 1985 Treaty, considering this treaty only supplementary to the 1985 Treaty. Article III (item 4) and Article IV (item 1) affirm both sides’ determination to early end the process of demarcation and stipulate that both sides need to adopt a master plan on demarcation by the end of 2005 so as to complete the work before December 2008.

This is a great success for the two countries. For the first time, the two countries have set specific objectives with a strong determination. Under this agreement, both sides will soon resume the process of demarcation which was discontinued 17 years ago.

2. Applying international principles and practice on boundary rivers and streams for delimiting the river and stream boundary line along the whole land boundary line between the two countries.

Particularly, the two countries have agreed to note in the Supplementary Treaty that “when there is any difficulty in applying the above-said provisions, the two countries will hold friendly exchange to work out a solution acceptable by both.”

3. The two sides have agreed to settle six points temporarily agreed in the 1985 Treaty. Three regions (including region 1 in Kon Tum province bordering on Rattanakiri province of Cambodia, region 2 in Gia Lai province bordering on Rattanariki province and region 3 in Dac Lac province adjacent to Mondulkiri province) have the same characteristics concerning dense forests and high mountains not clearly illustrated on the Bonne map attached with the 1985 Treaty, In addition, the areas along both sides of the boundary line have been uninhabited. After conducting joint field surveys, the two sides agreed to readjust the boundary line in these areas based on geographical factors. Three other regions between Vietnam’s An Giang province and Cambodia’s Kandal province, so far controlled by Vietnam or Cambodia, are not illustrated on the map attached with the 1985 Treaty. Therefore, the two countries agreed to make readjustments to meet the practice of management.    

4. The two sides agreed to assign the Mixed Committee on Boundary Issues the following tasks: (i) To draw up a master plan on the implementation of the demarcation roadmap by the end of 2005; (ii) To demarcate the whole land boundary line between Vietnam and Cambodia on the basis of the 1985 Treaty and the Supplementary Treaty; (iii) To draw a map illustrating the national boundary between Vietnam and Cambodia; and (iv) To prepare a protocol on the demarcation of the land boundary.

Significance of the Supplementary Treaty

The readjustments to the 1985 Treaty are objective, inevitable and compliant with international law and practice, meeting the common concerns and interests of the two states and peoples. They all originate from actual technical and managerial bases and comply with the two principles on delimitation of land boundary laid down in the 1983 Treaty.  The Supplementary Treaty affirms the validity of the 1985 Treaty and demonstrates Vietnam’s faithfulness and impartiality that it did not force Cambodia to sign unequal treaties. Vietnam’s act is admirable. The signing of the Supplementary Treaty has frustrated hostile forces’ attempts to abolish the two countries’ boundary treaties and agreements signed in the 1980s.

Together with the 1985 Treaty, the Supplementary Treat again clearly reflects the strong determination of the two states of Vietnam and Cambodia in resolving peacefully the existing boundary and territory issues.

The Treaty also contributes to raising the Vietnam-Cambodia relation to a new height under the motto of “Good neighbors, traditional friendship, comprehensive cooperation and long-term stability,” which was defined by Party General Secretary Nong Duc Manh and King Norodom Sihamoni in March 2005.

The 1999 Vietnam-China Land Border Delimitation Treaty, the 2000 Agreement on the Delineation of Bac Bo Gulf, the 2003 Agreement on the Delimitation of the Continental Shelf with Indonesia, and other agreements and treaties on settlement of the land and sea boundaries with Laos, Thailand and Malaysia as well as the 2005 Supplementary Treaty signed with Cambodia have attested to Vietnam’s goodwill in peacefully resolving boundary and territory issues with its neighboring countries and building a stable, peaceful, and cooperative environment for national development and integration.-

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