Amid rising security concerns in the Pacific, including a bolder North Korea and growing tensions across the Taiwan Strait, strong Japan-South Korea relations are more important than ever for maintaining regional stability. In their more than 60 years of bilateral relations, Japan and South Korea have deepened their economic and security cooperation, strengthening their position in the Pacific bloc. However, historical disputes have recently created new tensions that threaten to topple the alliance.
In 2018, two South Korean Supreme Court decisions ordered Japanese companies to compensate Korean citizens for forced labor. Japan objected to the ruling, arguing the decision violated the 1965 Bilateral Claims Agreement between the two countries. In response to the dispute, both countries downgraded each other’s trade status and South Korea threatened to pull out of a military intelligence-sharing pact with Japan. A later 2023 ruling by the Seoul High Court held Japan responsible for compensating Korean ‘comfort women’—a group of women forced into sexual slavery by the Japanese military during its occupation of the Korean peninsula. This ruling reignited the comfort women issue, a long-standing source of tension between the two countries, further threatening Japanese-Korean cooperation.
However, one long-standing dispute that has received little international attention involves two islets and 32 small outcroppings in the Sea of Japan. Known as Dokdo in Korea, Takeshima in Japan, and the Liancourt Rocks in the West, these islands are the subject of a nearly 300-year territorial dispute between Japan and Korea. Despite covering just 0.18 square kilometers and being largely uninhabitable, both Japan and Korea stubbornly assert ownership over the territory.
Japan’s primary interests in the islands are largely strategic. The territory contains some natural resources, most notably natural gas, and relinquishing the islands could weaken Japan’s military position in the Pacific region. Perhaps more importantly, under the United Nations Convention of the Law of the Sea (UNCLOS), the islands’ owner gains control over an additional 200 nautical miles of surrounding waters. For South Korea, however, the islands’ importance is largely symbolic. Dokdo symbolizes Korea’s independence from Japanese colonial rule, so for many Koreans, Japan’s claims to the islands amount to a denial of its colonial past.
As Japan continues to assert its claim over the islands, many Korean citizens have responded with fervent protests. In 2005, in response to the Japanese prefecture of Shimane declaring an annual “Takeshima Day,” two Korean protestors cut off their fingers outside the Japanese embassy in Seoul. In 2012, a Korean man rammed his truck into the Japanese embassy gates to protest Japan’s claims to the islands. The dispute even prompted a rare moment of cooperation between North and South Korea when, during the 2018 Asian Games in Jakarta, both Koreas submitted a request to the Olympic Council of Asia to fly a ‘unification flag’ depicting Dokdo during the event’s opening ceremony.
The dispute has also manifested in diplomatic contexts. In 2008, the Japanese Ministry of Education encouraged textbook publishers and teachers to teach their students that the Dokdo/Takeshima islands are Japanese territory. In response, South Korea recalled its ambassador to Tokyo. In 2012, Lee Myung-Bak became the first Korean president to visit the islands, which Japan responded to by recalling its ambassador to Seoul.
As tensions rise between the two states, the possibility of the dispute having disastrous military and economic implications increases. Already, the conflict has derailed a trilateral military meeting between the two countries and the U.S., initiated a minor trade war, and even pushed the Korean president to ban the Japanese emperor from visiting the country. Yet, a solution that is satisfactory to both sides seems increasingly unlikely. Both nations firmly assert full ownership of the islands, and South Korea’s stance suggests it does not even recognize the issue as a valid dispute. When Japan proposed bringing the case before the International Court of Justice (ICJ), Korea flatly declined, claiming the dispute was “not worth [the ICJ’s] attention.”
Japan has recently raised several legal claims to the islands, referencing historical acts of sovereignty and recent treaties with South Korea. Yet, as these arguments continue to weaken in the eyes of scholars and threats from other Pacific nations rise, there seems to be an increasing incentive for Japan to concede the islands to Korea. Especially considering the growing Korean nationalist movement, the possibility of Korea making any concessions seems unlikely. Instead of dragging the dispute out unnecessarily, Japan should concede the islands, focusing on economic relations with Korea and strengthening its position in more valuable territorial disputes.
Japan’s Weakening Legal Claims to the Dokdo/Takeshima Islands
There are two distinct legal arguments that should be addressed in the Dokdo/Takeshima dispute; the first is Japan’s assertion of terra nullius. Japan has long claimed that the Dokdo/Takeshima islands were terra nullius in 1905 when they were incorporated into Japan’s Shimane Prefecture. This claim of terra nullius means that the territory is not owned by anyone at the time of occupation and can therefore be legitimately acquired by the nation that ‘discovers’ the territory.
Since terra nullius implies the absence of prior sovereignty claims, Japan’s assertion of terra nullius over Dokdo/Takeshima suggests it had not claimed the islands yet. Under the doctrine of estoppel, an actor is barred from forwarding an argument that contradicts their previous statement. In other words, Japan is barred from forwarding any arguments about their own pre-1905 claims to the islands. Therefore, the key question in determining whether the islands were terra nullius in 1905 is whether another country made significant claims of sovereignty over the islands. In this case, the most likely contender would be Korea.
On this count, Korea argues that its pre-1905 actions on the islands constitute a legitimate claim of sovereignty. Because the islands are generally barren, little activity is required to establish occupation of the islands, so Korea argues that fishing activities by Koreans around the islands as well as its specific references to Dokdo in government documents were sufficient shows of sovereignty. Further, referencing Japanese maps and government documents that depict Dokdo as Korean territory, Korea argues that Japan acquiesced ownership of the islands to Korea before 1905. Especially considering international tribunals have historically been hesitant to acknowledge terra nullius claims, it seems unlikely that an international court would side with Japan on this count.
The second argument that should be addressed involves modern displays of effective sovereignty. In the case Yemen v. Eritrea, the Permanent Court of Arbitration (PCA) explained that the modern international law of acquisition of territory requires “the continuous and peaceful display of the functions of state within a given region.” Therefore, claims to Dokdo/Takeshima require a historical analysis of Japan and South Korea’s exercises of sovereignty over the islands.
As explained earlier, Japan’s terra nullius claims invalidate historical acts of sovereignty before 1905. And although Japan retained effective control over the islands for much of the early 20th century, these claims are not relevant because Korea was, at the time, a colony of Japan and was unable to contest Japan’s sovereignty. In other words, the most relevant actions to be considered when determining sovereignty occurred after Korea gained its independence in the 1940s.
On this count, Korea’s claims of sovereignty are generally more convincing than Japan’s. Since Korea’s first president Syngman Rhee drew the so-called “Peaceline” including Dokdo on the Korean side, Korea has exercised its territorial sovereignty over the islands through various acts. These include constructing a territorial monument in 1953, building a lighthouse in 1954, allowing citizens to settle on the island in 1980, building a helicopter landing facility in 1981, installing a radar facility in 1993, and building an anchoring facility in 1996.
Furthermore, since the 1940s, Japan has largely acquiesced to Korean sovereignty over the islands. Besides some written and oral protests in the early 1950s, Japan has done very little to maintain its claim to the island, especially compared to Korea’s high activity on the island. Further, Japan’s failure to address the issue in the 1965 Treaty normalizing relations with Korea is seen by many as a waiver of its claims to the island.
Although no international or domestic judicial body has adjudicated the claims to the courts yet, on its face, both of Japan’s claims to the islands seem to be weaker than Korea’s. Because of this weak legal standing, it would be generally ill-advised for Japan to seek international arbitration on the matter.
Feasibility of Binding International Adjudication
Even disregarding the strength of Japan’s legal claims to the islands, the feasibility of bringing the case before a court has become increasingly narrow. Japan has already proposed submitting the dispute to the ICJ in 1954, 1962, and 2012; each time, Korea denied the proposal. There is little reason to believe that Korea will reverse its position after denying arbitration for over 70 years.
In fact, there is evidence pointing to the contrary. Because Korea is a relatively young democracy, nationalist ideologies still run high in the country. As a result, sovereignty disputes with Japan are uniquely situated in the public eye. Unlike most countries, international relations are generally decided by the people, rather than political elites. For example, it was sagging poll numbers that pushed then-President Lee Myung-bak to visit Dokdo/Takeshima in 2012 and push a more nationalist message; the visit then prompted a ten-point rise in his approval ratings. The possibility of Korean politicians capitulating to Japan’s demands on issues like the Dokdo/Takeshima dispute could have disastrous effects on their political careers. In fact, Korean President Yoon Suk Yeol’s articles of impeachment in 2024 cited his “bizarre Japan-centered foreign policies” as justifications for his removal.
Because of this intense pressure politicians face from an increasingly patriotic voter base, there is little possibility of Korea accepting any adjudication on the matter, which could be viewed as a violation of Korean honor and sovereignty. Especially considering Korea’s current position—that Korea’s claims to Dokdo are absolute and uncontestable—the recognition of even the possibility that Japan’s claims might be valid would be viewed as a violation of the public trust.
Japan’s motivations towards the island have also been influenced by nationalism, especially since the more assertive Liberal Democratic Party (LDP) returned to power in 2012. However, as reflected by both government actions and public sentiment, Japan seems to be more motivated by practical reasons, such as expanding Japan’s territorial waters. Japan has consistently urged Korea to dismiss the war legacy of the island dispute and instead focus on the territorial and resource implications of the islands. Its willingness to accept arbitration on the issue also signals a more practical approach to the issue on the part of the Japanese.
In this way, even if Japan were to successfully gain submission to the ICJ and receive a favorable decision, two already unlikely outcomes, there is still the possibility that Korea will simply ignore the decision after facing pressure from its citizens. All things considered, any attempt to adjudicate the issue would not only place Japan’s already precarious claims to the island in jeopardy but also cause a diplomatic catastrophe with Korea that puts its economic and security interests at risk.
The Economic and Security Implications of this Dispute
Considering the legal and political infeasibility of Japan receiving a favorable decision through international arbitration, it seems the only possibility for Japan is to maintain the status quo. However, as previous diplomatic squabbles over the issue have shown, maintaining the status quo could have significant economic and security impacts.
Primarily, Japan and Korea are currently vital trade partners. In 2023, South Korea exported $28.4 billion to Japan and Japan exported $42.7 billion to South Korea, each constituting the other’s fourth-largest trading partner. For much of the 20th century, this trade reliance has integrated the Japanese and South Korean economies, specifically in the electronics sector. However, diplomatic disputes now place this economic relationship in peril. In recent years, both countries have accounted for less of the other countries’ exports, in many cases seeding critical trading grounds to China.
The major fear is that both countries will be willing to forsake their economic interdependence for political issues. Although a relatively small island whose military and economic significance are far outweighed by the benefits of continued Japan-South Korea cooperation, nationalist tendencies continue to run high on the Korean side and Japan has thus far refused to back down. Further escalation of the Dokdo/Takeshima dispute could plunge both countries into major economic downturns, threatening the stability of the broader East Asian bloc.
The Dokdo/Takeshima dispute also has significant military implications, particularly as it pertains to other territorial disputes that Japan has with China. Specifically, the Senkaku Island dispute bears the most significance because of its similarities to the Dokdo/Takeshima dispute. Japan’s de facto control over the islands since 1895 put it in a similar position to that of Korea with the Dokdo/Takeshima islands. Recognizing the importance of established sovereignty and development of the islets in the Dokdo/Takeshima dispute could theoretically strengthen its position in the Senkaku dispute, a much more significant disagreement (because of the island’s oil reserves and proximity to key shipping lines) with a potentially more dangerous actor.
Potential Paths Forward for the Dokdo/Takeshima Islands
Moving forward, it is in Japan’s best economic and security interests to acknowledge Korea’s sovereignty over Dokdo/Takeshima. In exchange, Korea could acknowledge that the islands will not impact territorial rights under the UNCLOS or create a resource-sharing agreement for the natural gas and mineral deposits around the islands.
For Korea, such an agreement would greatly satiate the country’s nationalistic fervor and improve public sentiments toward Japan. For Japan, seeding the argument would strengthen its relationship with an important economic ally moving forward and produce a precedent to cite in territorial disputes with China, all without conceding significant amounts of territory to Korea.
Of course, political support for Japanese claims to the island still runs high in the country. However, considering the opportunity cost of Japan maintaining its claims to the islands are critical military and economic ties with South Korea, the costs of Japan maintaining its weakening claims to the islands far outweigh the political benefits it draws from remaining in a perpetual state of contention with Korea.
In effect, the Dokdo/Takeshima islands are nothing more than a bargaining chip that Japan has been holding against Korea for over a century now. Japan still has the opportunity to use the islands to strike a bargain with Korea, but it has to cash in now before it’s too late.