The Boundary Line of The Seas of The Republic of Indonesia and The Republic of Singapore

As countries that have territorial sea borders, the Republic of Indonesia and the Republic of Singapore have a Territorial Sea Boundary Lines Agreement signed in Jakarta on May 25, 1973, which then ratified into Law Number 7 of 1973 dated December 8, 1973, and an agreement on the Determination of The Sea Boundary Line of the two countries in the Singapore Strait Western Part signed in Jakarta on March 10, 2009, was later ratified into Law No. 4 of 2010 dated June 22, 2010. On September 3, 2014, in Singapore, the two sides re-signed an agreement on the Determination of the Sea Boundary Line of the two countries in the Singapore Strait Eastern Part, completing the two (2) previously agreed agreements.

Legal History Journey

The determination of the territorial sea boundary line in the Singapore Strait Western Part is necessary to provide legal certainty on the sovereign territory of the Republic of Indonesia and related to the two countries’ interests in the territory. The Singapore Strait has a very high strategic value considering that it is a very dense international shipping route that links Continental Europe and Southeast Asia, East Asia, and the Pacific. For Indonesia, the strait is also like the lifeblood of Indonesia’s shipping routes to other regions of the world.

Since the enactment of the Government Regulation in Lieu of Law (Perpu) of The Republic of Indonesia (RI) Number 4 of 1960 on Indonesian Waters, the sea width of the Indonesian territory was expanded to twelve (12) nautical miles, measured from the straight baselines that connect the outermost points of the islands or parts of the outer islands in the territory of Indonesia. Therefore, the entire Indonesian archipelago is a unitary territory, and all the waters located next to the coast of the territory’s sealine are the territory of the Republic of Indonesia.

One of the consequences of the enactment of the above-mentioned law is that some parts of the waters once free seas have now become Indonesian territorial waters or Indonesian inland waters. That is also the case in the Singapore Strait.

At that time, the Government of the Republic of Singapore adhered to a sea width of three (3) nautical miles. Thus, the issue arises about the location of the sea boundary lines of each country in the narrow Singapore Strait, namely in the part of the Singapore Strait where the distance between the Indonesian baselines and the Singapore baselines is less than fifteen (15) nautical miles. The firmness of this boundary line is indispensable by the Governments of both countries, especially to be able to provide guarantees of legal certainty (rechtszekerheid) in the sea of each Country’s territory.

Based on the above considerations, negotiations were held between both Governments in Singapore from May 7 to May 8, 1973, which resulted in the “Agreement Stipulating the Territorial Sea Boundary Lines Between Indonesia and the Republic of Singapore in the Singapore Strait”.

The main content of the Agreement is that the sea boundary line of Indonesia and the sea of Singapore in the Singapore Strait is a line consisting of straight lines drawn between the points whose coordinates are listed in the Agreement above.

In addition, referring to the International Hydrographic Organization’s (IHO) regulations, the Singapore Strait is a strait located in Indonesian waters from Karimun Kecil Island to Bintan Island, Singapore waters, and Malaysian waters; from Tanjung Piai to Tanjung Tuas; and from Johor to Tanjung Penyusup. The Singapore Strait maritime area toponym has been stipulated in the IHO document Number S-23 of 1953.

Indonesia and Singapore already have a Territorial Sea Boundary Lines Agreement signed in Jakarta on May 25, 1973, which was ratified into Law No. 7 of 1973 on December 8, 1973. It governs only a portion of the Indonesia-Singapore sea boundary segments in the Singapore Strait. Other segments that need to be discussed to resolve the entire maritime boundary between the Republic of Indonesia and the Republic of Singapore are the western segment (in the Nipa-Tuas Island region), the eastern segment 1 (in the Batam-Changi Island region), and the eastern segment 2 (in the Bintan-South Ledge Island/Middle Rock/Pedra Branca region).

The continuation of negotiations on the determination of the territorial sea boundary line in the Singapore Strait Western Part with the Government of the Republic of Singapore began on February 28, 2005, and ended on March 10, 2009, when the Foreign Ministers of both countries signed an agreement in Jakarta on the Determination of the Sea Boundary Line of the two countries in the Singapore Strait Western Part.

In the negotiation process, Indonesia has always based its position on the United Nations Convention on the Law of the Sea (UNCLOS) of 1982, refused to use the reclamation results as the Basis of Measurement (BOM), and used the original map reference of 1973, the base points in Nipa Island, and the baseline of the Indonesian archipelago drawn from Nipa Island to Karimun Kecil Island.

This stipulates that the determination of the actual location of the coordinate points above the sea will be determined in a manner that will be mutually agreed upon by authorized officials from both countries. In accordance with the prevailing regulations in Indonesia, the officials in question are the National Coordinating Agency for Surveys and Mapping (Bakosurtanal) and the Indonesian Navy (TNI AL).

The negotiations claimed that the boundary line of the Treaty between the Republic of Indonesia and the Republic of Singapore, concerning the determination of the sea boundary line of the two countries in the Singapore Strait, signed on May 25, 1973 and the territorial sea boundary line in the Singapore Strait Western Part signed on March 10, 2009, is described in Appendix “B” of the Treaty.

Furthermore, based on the Government Regulation in Lieu of Law (Perpu) of The Republic of Indonesia (RI) Number 4 of 1960 to Law Number 6 of 1996 on Indonesian Waters and Law Number 32 of 2014 on Marine, as well as the UNCLOS regulations of 1982, especially Part II of the Territorial Sea, Indonesia invites Singapore to establish the boundary of the Territorial Sea between neighboring countries through a third negotiating method.

Thus, an agreement was made on September 3, 2014, which aims to establish a territorial sea boundary line between Indonesia and Singapore in the Singapore Strait Eastern Part that provides legal certainty about the sovereign territory of the Unitary State of the Republic of Indonesia, protect Indonesia’s interests in the Singapore Strait, and strengthen friendly ties between the two countries.

The Treaty dated September 3, 2014, was then ratified into Law of the Republic of Indonesia Number 1 of 2017 concerning ratification of the Agreement between the Republic of Indonesia and the Republic of Singapore on the Determination of the Sea Boundary Line of the two countries in the Singapore Strait Eastern Part of 2014.

The territorial sea boundary line between the Republic of Indonesia and the Republic of Singapore in the Singapore Strait Eastern Part is a continuation of the territorial sea boundary line in the Singapore Strait Central Part in accordance with the Agreement between both countries concerning the Determination of the Sea Boundary Line of the two countries in the Singapore Strait of 1973 (Treaty of 1973) as a line consisting of straight lines drawn between the coordinates’ points as follows: