Historical and Legal Basis of Japan’s Territorial Disputes
Although Japan’s imperial expansion concluded at the end of World War II, its colonial legacy continues to fuel regional instability. Critically, unresolved disputes between Japan, Korea, China, and Taiwan over the Takeshima and Senkaku islands remain at a stalemate. Rooted in Japan’s annexation of the islands in the late 1890s to 1910s, the legal conflict over rightful ownership has evolved from territorial disagreements into significant threats to regional security.
Geographically, both island territories are small, rocky formations with limited habitability. Takeshima, known as the Liancourt Rocks, is inhabited by two individuals, while Senkaku, known as the Pinnacle Islands, is uninhabited. Because of the unresolved sovereignty disputes, each state identifies the islands differently. The Liancourt rocks, located between Japan and Korea, are respectively known as Takeshima and Dokdo, while the Pinnacle islands, between Japan and Taiwan, are respectively known as Senkaku and Diaoyutai. Despite minimal land value, each nation unequivocally affirms ownership for symbolic and security reasons, creating a diplomatic stalemate where neither claimant is willing to concede sovereignty.
Regional disputes over the islands began in the aftermath of World War II through the ambiguities left in the San Francisco Treaty. The treaty forced Japan to renounce and return all of the land it had taken to successor states. Most critically, Taiwan was restored to the Republic of China, and Korea was returned to the Republic of Korea. However, the territories that Japan owned, such as the Liancourt Rocks and Pinnacle Islands, were not allocated to successor states, deferring it to the post-war world to decide. The failure of the San Francisco Peace Treaty to resolve the disputes created significant uncertainty that international law was ultimately unable to settle due to its unenforceable nature. Consequently, disputes over the territories today have resulted in close military encounters and can be the primary catalyst for a regional armed conflict.
Japan and Korea both cite historical documents to support their territorial claims in the Liancourt Rocks. While Japan points to Shimane Prefecture's incorporation of Takeshima in 1905, South Korea highlights a 1900 Imperial ordinance, occupation records from ancient Korean kingdoms, and post war agreements, such as Yalta and instructions from SCAP. However, Japan—using the resolution of similar territorial disputes by the International Court of Justice (ICJ) as justification—believes precedent is in favor of Japanese ownership. In the territorial dispute between Malaysia and Indonesia over islands similar to Japan’s, the ICJ cited that Malaysia significantly developed the islands under long British occupation, whereas Indonesia did not. Therefore, the islands were awarded to Malaysia. Similarly, Japan annexed and occupied the Liancourt Rocks in 1905, occupying and attempting to forcefully integrate the Korean population until 1945. In 1954, after major territories were returned, Korea took de facto control of the islands while still being officially owned by Japan.
In 1954, 1962, and 2012, Japan offered to resolve the dispute through the International Court of Justice, but was rejected by Korea each time, maintaining that there was no dispute in existence as the islands irrefutably belonged to them. Strategically—as the ICJ may rule in favor of Japanese ownership based on precedent cases—Korea has little incentive to participate in an ICJ hearing. In 2015, Japan and Korea held a high-level ‘two-plus-two’ dialogue, otherwise known as a joint security discussion between national foreign and defense ministers. In the meetings, Japan continued to affirm ownership and control over the Liancourt Rocks. Ultimately, minimal progress was made, as Korea continues to occupy the Liancourt Rocks with only two permanent residents, maintaining claims of sovereignty and history on the island. As wartime tensions remain unresolved, occupation of the island serves as a symbol of Korean independence beyond tangible benefits of ownership.
By contrast, the Pinnacle Islands, being five uninhabited rocks in the ocean, lacked the same post-war value or significance as the Liancourt Rocks. However, the Islands find value in another sector. In 1969, a report from the United Nations Economic Commission for Asia and the Far East (ECAFE) found that rich oil and gas reserves lie in the area. After the ECAFE’s report, control of the islands presented significant economic and security opportunities due to the abundance of natural resources and fisheries, as well as its strategic location, escalating regional tensions.
The historical background of the Pinnacle Islands is also varied. The dispute spans to ancient times, where China draws claims to ownership from the 1400s using records of imperial envoys of the Ming and Qing courts. Then, the islands were reportedly present on maps from the 1500s to the 1700s. On the other hand, Japan first possessed the islands in 1895 in the colonial era, following the first Sino-Japanese war. The Chinese claim that the islands were stolen by the Japanese as a result of the Treaty of Shimonoseki, which ended the first Sino-Japanese war by ceding Taiwan and surrounding territories. Conversely, the Japanese claim extensive surveying by the Okinawa Prefecture revealed no Chinese presence, and as such, the islands were terra nullius. Terra nullius is a legal doctrine meaning land belonging to no one, grants a state’s right to exercise sovereignty. The Japanese held control of the islands until the period from 1951 to 1972, when the U.S. temporarily took control as agreed to in the San Francisco Peace Treaty.
Following Japan’s defeat in World War II, the Senkakyu islands changed hands many times, creating further ambiguities over the islands’ rightful owner. After 1972, the U.S. transferred ownership of the Ryūkyū islands, a larger group of islands including the Pinnacles, back to Japan pursuant to the Okinawa Reversion Agreement. The transfer prompted swift backlash from China, citing the Cairo and Potsdam declarations—postwar treaties that forced Japan’s unconditional surrender and return of occupied territories such as Taiwan. By accepting the Cairo and Potsdam agreements, it was implied that the Senkakyu islands would be returned. However, sovereignty of the islands was not explicitly given up in the San Francisco Peace Treaty, as China had no involvement in the treaty’s making. As such, Japan claims that due to the “residual” sovereignty held during U.S. occupation, they are entitled to the islands. Japan has consistently exercised activities that demonstrate ownership, such as having the U.S. pay rent to occupy the territory. Since the 70s, protests between the Chinese, Taiwanese, and Japanese have been prolific, primarily waving flags to display ownership. Furthermore, the disputes have created major security implications in the 2010s, with aggressive Chinese maritime behavior and establishment of an Air Defense Identification Zone over the area. To this day, China, Japan, and Taiwan are still conflicted on the legality of military drills and actions indicating ownership of the islands.
As no state is willing to change their position on these disputed territories, no end to the disputes is in sight. Korea’s refusal to negotiate and China’s relentless efforts to change the status-quo signal a difficult path to peace for Japan, as diplomatic relations have failed to de-escalate potential military actions. In retrospect, the inability of the San Francisco Peace Treaty to address Japan’s minor territories seems to have sparked an endless issue, potentially destabilizing the region.