Japanese Maritime Claims: The Geopolitics of Law

by Evan Enns
February 7th, 2020

Over the past decade, Japanese President Shinzo Abe’s Liberal Democratic Party has been steadily expanding Japan’s military capabilities. For example, October of 2018, the Japan Ground Self-Defense Force’s (JGSDF) Amphibious Rapid Deployment Brigade participated in amphibious warfare training with the Filipino navy and the U.S. Marine Corps. This recently-activated marine force is the first of its kind for Japan since the end of the Second World War, representing a substantial change in Japanese defense policy. Also for the first time since the war, Japan has announced the future deployment of its first aircraft carrier. Their deliberation over the purchase of F-35 stealth multirole fighters from the United States is seen by some legal scholars as a violation of Article 9 of Japan’s constitution forbidding the development of offensive military capabilities. In order to understand the escalation of Japan’s defense policy, it is important to conduct an analysis of the economic, geopolitical, and historical factors that influence it.


The Asia-Pacific region is currently rife with territorial and maritime disputes, and Japan is one of the major claimants. Of these disputes, Japan’s discord with the People’s Republic of China (PRC) and Taiwan over several islands in the East China Sea—known as the Senkaku Islands in Japan, the Diaoyutai Islands in Taiwan, and the Diaoyu Islands in China—proves to be one of the most contentious. The Senkaku islands, are of vital interest to all three parties. This is partly due to the discovery of vast reserves of oil and natural gas that lie off the coast of the islands. More crucially, however, the islands are a part of the first island chain, which China views as a geostrategic threat and a primary target of its military doctrine; the first island chain enables the United States to contain the People’s Liberation Army Navy (PLAN) and to maintain airstrike capability over the Chinese mainland. Several military confrontations have occurred over the islands, including standoffs between naval vessels and scrambled fighter jets. One was prominently displayed when a Chinese frigate sailed at the edge of the Senkaku Islands’ 12 mile territorial zone, constituting the first engagement of the People’s Liberation Army Navy (PLAN) in the dispute, and causing protests by the Japanese government. Incidents such as this contribute to growing perceptions of the dispute as a serious threat to peace and stability throughout East Asia. 


While the Senkaku Islands dispute tends to receive the most media coverage, there are several other maritime conflicts that are important to Japan. The debate over the sovereignty of the Kuril Islands, for example, is a key issue for the Japanese Ministry of Foreign Affairs and has remained a major sticking point in talks between the Japanese and Russian governments. Russia claims and administers all of the islands, while the Japanese maintain a claim on the southern portion of the Kuril Islands (the Habomai Islands, Kunashir Island, Shikotan Island, Iturup). Japan also competes with South Korea and China over another piece of territory. The Liancourt Rocks (referred to as Dokdo in Korean and Takeshima in Japanese) exist in an important location in the Sea of Japan, marking the exit of the Tsushima strait. However, these islands are a symbolic part of larger conflict between South Korea and Japan over history. Especially due to the fact that the South Korean government views them as being the first territory taken in Japan’s eventual occupation of Korea. Similarly, the Okinotorishima rocks have stirred conflict among Japan, China, and South Korea. South Korea currently administers the Liancourt Rocks while Japan holds sway over Okinotorishima. These cases illustrate Japan’s struggle for control of ocean space, for which no resolutions have been yielded while their relations with other regional actors have degraded.


These disputes exist in a framework of specific international agreements. The most relevant international agreement for maritime disputes, in regard to the conflicts that Japan faces, is the United Nations Convention on the Law of the Sea (UNCLOS). This convention provides that every state may maintain an Exclusive Economic Zone (EEZ) of 200 nautical miles off of its coast and baseline (low water line) or to the median line between two states, within which the state holds exclusive rights to resource exploitation and the responsibility to defend its zone. The Japanese archipelago includes around 6,852 islands, thus granting Japan dominion over the fifth-largest EEZ in the world: an area of 4,479,358 km2. The Senkaku Islands are surrounded by enough gas reserves to meet the economic needs of Japan for 100 years as well as enough cobalt for 1,300 years. Some debate exists regarding the determination of whether a state’s continental shelf is considered a part of its EEZ if it extends beyond the Zone. This contention is one of the underlying factors of the ongoing maritime dispute between China and Japan over the Senkaku Islands. The UNCLOS is also pertinent to the Okinotorishima conflict, as the Convention states that for an island to have an EEZ it must remain above water at high tide and be habitable as well as economically sustainable. Accordingly, China contests Japan’s characterization of Okinotorishima as an island, citing its inhabitability and lack of economic potential. While China does not dispute Japan’s claim to the territory, it still does not recognize the existence of an EEZ in that area because, as stipulated by the UNCLOS, it would require China to obtain approval from Japan for oceanographic research at least 6 months in advance of conducting it. This requirement would greatly reduce China’s ability to conduct naval operations in the area between Taiwan and Guam, threatening China’s attempts to isolate Taiwan from the United States. Challenges over EEZs have been brought to dispute settlement mechanisms such as the International Tribunal for the Law of the Sea (ITLOS). Japan has filed four cases with the ITLOS, two of which were filed against Russia. These court cases have helped manage relations between the two countries, allowing allowing smaller crises to be resolved without prejudice, while long-term solutions are left for bilateral negotiations. The International Court of Justice (ICJ) has also been used to solve maritime disputes. In fact, Japan proposed that its dispute with Korea over the Liancourt Rocks be brought to the ICJ in 2012—a proposal that the South Korean Foreign Ministry promptly declined.


The aforementioned disputes over maritime boundaries have been shaped by the end of the Second World War and its resulting treaties. The most significant of these is the 1951 Treaty of San Francisco, which forced Japan to cede sovereignty over the southern portion of the Sakhalin Islands and all of the Kuril Islands to the Soviet Union. While this may seem straightforward, the treaty does not explicitly stipulate that Japan would have to recognize Russia’s sovereignty over the islands, which drove the Soviet Union to ultimately reject the treaty. The Japanese government still challenges whether Etorofu and Kunashiri islands are part of the Kuril island chain and thus included in the San Francisco Treaty. Russia also views the Yalta Agreement to be the superseding document pertaining to the Kuril Islands, as it explicitly granted the Soviet Union the entire island chain. These differences in historical perspective have been, and most likely will continue to shift the relationship between these two states.


What underlies all of these legal issues is Japan’s reliance on other states for their natural resources. Under these circumstances, Japan has sought to secure itself a stake in the natural resources of the Pacific and in the trade routes that sustain the Japanese economy. It has attempted to achieve its goals through diplomacy and the use of international law, which can be seen through Japan’s dialogue with Russia over the Kuril Islands and Japan’s attempts to resolve the Liancourt dispute through the International Court of Justice. However, as the Senkaku Islands disagreement has shown, conflicts over the legality of Japanese claims have also resulted in military confrontations. Without the capability to enforce its claims, Japan has had to rely on the United States to support its interests while being openly challenged by larger military forces in the Asia-Pacific such as China. This state of affairs is changing. As the Japanese navy grows in strength, so too does the risk for escalation. Dialogue-based settlements among claimants and submission of disputes to international courts should be of the utmost priority to policymakers seeking to avoid a military calamity.

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