The port of Tokyo is pictured on November 4, 2021. (Photo: Charly Triballeau / AFP)

Why UNCLOS Matters

Cooperation, Challenges and Charms: The UNCLOS for Japan


Japan has made solid contributions to the global rules-based order. Notwithstanding Japan’s efforts for international cooperation, challenges remain in implementing UNCLOS.

Editor’s Note:

This article is part of “UNCLOS 40th Anniversary Series – Why UNCLOS Matters” conceptualised by the Blue Security programme. The series, which commemorates the 40th anniversary of the UN Convention on the Law of the Sea, brings together established and emerging maritime security scholars from Southeast Asia and the broader Indo-Pacific to address the pertinence and relevance of UNCLOS. Blue Security brings together Australian and Southeast Asian experts to look at a range of maritime security issues across the region. The series was developed by Dr. Troy Lee-Brown and Dr. Bec Strating.

Japan is an island nation with more than 6,800 islets. It has an exclusive economic zone (EEZ) that extends up to more than 4.4 million square kilometres. It has rich oil, natural gas, minerals and hydrothermal deposits on its continental shelf. In 2019, 99.6 per cent of Japan’s trade per tonnage was made through maritime transportation. Japanese shipping companies have the second largest share of the global maritime trade. Therefore, Japan needs to secure the safety and freedom of navigation, logistics flows and transportation infrastructure. These include constructing and maintaining ports, the communication infrastructure established through submarine cables, and the sustainable development of ocean resources. None of this is possible without international cooperation.

The United Nations Convention on the Law of the Sea (UNCLOS) has been indispensable for Japan because the instrument sets out a universal yardstick for the rights and obligations of the parties. It has been the foundation for Japan to communicate, negotiate, coordinate and settle disputes with other states.

The Rule-Based Maritime Order

UNCLOS is a living instrument which incorporates the norms and practices as they emerge. Japan has contributed to the norm-making process to secure the rules-based maritime order. It includes declaring the Three Principles of the Rule of Law at Sea in 2014 and pushing the Quality of Infrastructure Investment Principles at the G20 Summit in 2019. The former declares that states should make their claims based on international law, that they should not use force or coercion to pursue their claims, and that they should seek dispute settlement by peaceful means. The latter maps out principles to develop sustainable infrastructure projects necessary for connectivity. In a broader context, Japan has sponsored the Free and Open Indo-Pacific (FOIP) to pursue economic development through enhancing connectivity and secure safety by assisting other countries with capacity building on maritime law enforcement, disaster risk reduction and non-proliferation.

Japan has worked on maintaining international architectures to govern the maritime domain. It has financially and substantially contributed to the organs established under UNCLOS, including the International Tribunal for the Law of the Sea, the Commission on the Limits of the Continental Shelf and the International Seabed Authority. It plays a central role in the International Maritime Organization (IMO) in ensuring the safety of navigation. It is a member of major regional fisheries management organisations and has backed the arrangements and implementation of conservation and management measures. It actively participates in the United Nations Environment Programme (UNEP) and other organisations to prevent pollution and preserve the marine environment.

Japan has also directed the drafting and establishment of various treaties to govern the oceans. It adopted the Regional Agreement on Anti-Piracy in Asia (ReCAAP), which entered into force in 2006 and played a key role when the IMO led the adoption of the Djibouti Code of Conduct in 2009. It has also committed to the work of the Intergovernmental Conference for the biological diversity of areas beyond national jurisdiction (BBNJ) agreement negotiation and to draft the International Seabed Authority’s regulations on mineral exploitation.

The Comprehensiveness of the UNCLOS and The Challenges for Japan

Notwithstanding Japan’s efforts for international cooperation, challenges remain in implementing UNCLOS. Japan has long developed a unique maritime policy and interpretation of the law of the sea. As a result, some Japanese domestic legislation and policies are not well-adapted to the comprehensiveness of the treaty. While none of the policies contravenes international law, it may be time that Japan reconsidered its narratives.

For example, the status of Okinotorishima has been an issue. Japan justifies its status as an island under Article 121(1) by demonstrating its capability for economic activities. The islet is expected to be utilised for various types of scientific research and the basepoint for resource exploration.

Yet, China and the Republic of Korea (ROK) have criticised Japan’s position since the early 2000s. They argue that the island is a rock under Article 121(3) and does not enjoy the jurisdictional waters. It is reported that oceanographic research by Chinese have been taking place within Okinotorishima’s EEZ without Japanese government’s permission (see here and here).

In response, the Japanese government explains (see here and here) that its maritime entitlement is based upon Article 121(1). This part is in line with the International Court Justice (ICJ) jurisprudence that islands, regardless of their size, enjoy the same status, and therefore generate the same maritime rights, as other land territory (Qatar v. Bahrain, 2001, para. 185; Nicaragua v. Colombia, 2012, para. 139).

However, Japan further explains that Article 121(3) deals with “a rock which is inhabitable and does not define what an island is,” and the requirements of the rocks are not well-established. This explanation does not agree with the ICJ, which held that “the entitlement to maritime rights accorded to an island by the provisions of paragraph 2 [of Article 121] is expressly limited by reference to the provisions of paragraph 3” and “the legal régime of islands set out in UNCLOS Article 121 forms an indivisible régime” (Nicaragua v. Colombia, 2012, para. 139). If Japan is to accept this interpretation, it should also clarify its position on the definition of the rock provided under Article 121(3).

Japan has made many efforts to promote connectivity, yet problems have often overshadowed these efforts, including geopolitical competition in East Asia, territorial and maritime disputes, political mistrust and security concerns. Japan’s contribution to fostering peace and security for the region and the global domain is only achievable through greater adherence to the rule-based order that the UNCLOS supports.


This article is part of the ‘Blue Security’ project led by La Trobe Asia, University of Western Australia Defence and Security Institute, Griffith Asia Institute, UNSW Canberra and the Asia-Pacific Development, Diplomacy and Defence Dialogue (AP4D). Views expressed are solely of its author/s and not representative of the Maritime Exchange, the Australian Government, or any collaboration partner country government.

Yurika Ishii is an associate professor at the National Defense Academy of Japan.