Japan Unites South Korea, and China Face Off Over Sovereignty of Islands and Waters with Surging Tensions: What Travellers Need to Note

Published on December 19, 2025

Island disputes among Japan, South Korea and China are deeply rooted in history and remain central to the region’s geopolitics. Because these countries are industrialized maritime nations whose identity and security are tied to the sea, control of small islands can affect fishing rights, energy exploration, trade routes and national pride. This article reviews the major island disputes — Senkaku/Diaoyu, Takeshima/Dokdo, Northern Territories (South Kuril Islands), South China Sea islands, Ieodo/Socotra Rock and Okinotori Reef — relying on official statements and government publications issued up to December 2025. It outlines each side’s official position, recounts recent events and assesses the prospects for resolution.

Senkaku (Diaoyu) Islands dispute

Japanese perspective

Japan refers to the uninhabited islands in the East China Sea as the Senkaku Islands. The Japanese Ministry of Foreign Affairs (MOFA) insists that these islands are “clearly an inherent part of the territory of Japan”[1]. In MOFA’s view, the islands were neither unclaimed nor occupied by any other state when Japan incorporated them in 1895. Japan has exercised valid control over the islands and, therefore, asserts that “there exists no issue of territorial sovereignty to be resolved”[1]. Tokyo maintains that it will act firmly but calmly to protect the islands while striving for peace and stability in the region[1].

Chinese perspective

China calls the same islands Diaoyu Dao and its affiliated islets. Beijing argues that these islets have been Chinese territory since ancient times and that there are clear historical facts and solid legal bases supporting this claim. According to a statement by a Chinese foreign ministry spokesman in December 2025, Japan’s reliance on selective documents to assert sovereignty “only highlights the weakness and absurdity of its claims”[2]. Chinese official media regularly argue that Diaoyu Dao has been part of China’s coastal defense system for centuries[2]. China has repeatedly urged Japan to respect China’s territory and sovereignty and to take practical measures to improve relations[3].

Recent developments (2024‑2025)

The dispute has been marked by confrontations between Japanese coastguard vessels and Chinese maritime patrols. In October 2024, China and Japan held high‑level consultations on maritime affairs. China elaborated its position regarding the East China Sea, Diaoyu Dao, the South China Sea and the Taiwan Straits and urged Japan to respect China’s territorial sovereignty and security[3]. Despite occasional diplomatic discussions, both sides continued to send official ships into waters around the islands and both governments remained steadfast in their claims through December 2025.

Takeshima (Dokdo) dispute

Japanese perspective

The pair of rocky islets known as Takeshima in Japan lies roughly midway between Japan and the Korean Peninsula. Japan insists that the islets are an inherent part of its territory based on historical facts and international law. According to the Japanese MOFA, Takeshima was “incorporated into Shimane Prefecture” in 1905, and there is no basis to South Korea’s claims. Tokyo contends that the Republic of Korea (ROK) has been “illegally occupying Takeshima without legal grounds” and calls on Seoul to settle the dispute calmly based on international law[4]. Japan has protested South Korean activities on the islets and continues to assert sovereignty in diplomatic notes and school textbook approvals.

South Korean perspective

South Korea calls the islets Dokdo. The ROK government insists that Dokdo is an integral part of Korean territory historically, geographically, and under international law. In March 2025, the South Korean foreign ministry expressed deep regret over Japanese high‑school textbooks that distorted history and made preposterous claims over Dokdo[5]. The ministry strongly protested and demanded corrections, emphasizing that Dokdo is an integral part of the ROK’s territory[5]. In February 2025, Seoul again protested Japan’s “Dokdo Day” events, calling them unjustified and urging Tokyo to stop making sovereignty claims[6]. Seoul also protested Japanese foreign‑minister remarks on Dokdo and noted that repeated claims hinder future‑oriented relations[7].

Recent developments (2024‑2025)

Japan’s approval of new textbooks and recurrence of local ceremonies like “Takeshima Day” prompted strong protests from South Korea. Seoul continued to station police on the islets and maintain a research station. Both sides exchanged diplomatic notes, but there were no significant negotiations by late 2025. The dispute remains an obstacle in Japan‑ROK relations, even as the two countries cooperate on broader security issues such as North Korea.

Northern Territories (South Kuril) dispute

Japanese perspective

Japan refers to four islands at the southern end of the Kuril chain — Etorofu (Iturup), Kunashiri (Kunashir), Shikotan and Habomai — as the Northern Territories. The Japanese government argues that these islands are not part of the Kuriles but are Japan’s inherent territory. MOFA states that Japan discovered and surveyed the islands before Russia and established control by the early 19th century; the 1855 Treaty of Commerce and Navigation confirmed the boundary[8]. Japan contends that the Soviet Union occupied the islands between 28 August and 5 September 1945 and has continued to hold them without legal grounds, deporting about 17,000 Japanese residents[8]. Tokyo insists that these islands were never ceded and continues to seek their return as a prerequisite for a peace treaty with Russia.

Russian perspective

Russia administers the islands as part of its Sakhalin Oblast and refers to them as part of the South Kuril Islands. Moscow argues that the islands were acquired as spoils of war and that its sovereignty is enshrined in post‑World War II arrangements. Russia maintains a military presence and has promoted development projects on the islands. In peace‑treaty negotiations, Russia has occasionally offered to discuss the return of Shikotan and the Habomai islets but not Etorofu or Kunashiri. However, the Russian invasion of Ukraine in 2022 led Moscow to suspend negotiations, citing Japan’s alignment with Western sanctions.

Recent developments (2024‑2025)

Negotiations have remained stalled. Russia continued to fortify its presence and stage military exercises in the region, while Japan lodged formal protests. As of December 2025, there is little prospect of immediate resolution, but Tokyo continues to assert its claim and calls for the return of all four islands[8].

South China Sea islands dispute

Chinese perspective

China asserts sovereignty over islands in the South China Sea—including the Nansha (Spratly), Xisha (Paracel), Zhongsha (Macclesfield Bank and Scarborough Shoal) and Dongsha (Pratas) groups. A government statement issued on 12 July 2016 stressed that these islands have been part of China for more than two thousand years and that China was the first to discover, name and exercise sovereignty over them[9]. The statement declared that the islands and their adjacent waters constitute China’s internal waters, territorial sea, contiguous zone, exclusive economic zone (EEZ) and continental shelf[9]. It asserted China’s historic rights in the South China Sea and denounced other states’ occupation of Chinese islands, while pledging to resolve disputes through negotiation and maintain freedom of navigation[9].

China refused to participate in the Philippines v. China arbitration under the UN Convention on the Law of the Sea (UNCLOS). In July 2016, the arbitral tribunal ruled that China’s historic claims had no legal basis. China responded by declaring the award “null and void” and stating that it neither accepts nor recognizes it[10]. Beijing argued that the arbitral tribunal lacked jurisdiction and that the case violated bilateral agreements[10]. China reaffirmed that its territorial sovereignty and maritime rights would not be affected by the award[10].

Southeast Asian and U.S. perspectives

The Philippines, Vietnam, Malaysia and Brunei claim overlapping portions of the Spratlys and adjacent waters. Following the 2016 arbitral ruling, Manila sought to engage China diplomatically while occasionally protesting Chinese activities. Vietnam continued to fortify features it occupies and to protest Chinese maritime militia swarming near its oil projects. The United States has not taken a position on sovereignty but conducts freedom of navigation operations to challenge what it views as excessive maritime claims.

Recent developments (2024‑2025)

In late 2024 and 2025, Chinese coastguard vessels increased patrols around Second Thomas Shoal and Reed Bank, leading to confrontations with Philippine vessels. Vietnam reported further harassment by Chinese maritime militia. Meanwhile, ASEAN‑China negotiations on a Code of Conduct made modest progress but failed to produce a final agreement.

Ieodo (Socotra Rock)

Ieodo (also known by its Chinese name Suyan Rock or internationally as Socotra Rock) is a submerged reef located about 150 km southwest of South Korea’s Jeju Island. Because it does not protrude above the sea surface, it cannot be claimed as territory under international law. The ROK foreign ministry emphasized in a 2013 press briefing that “Ieodo is a submerged rock, not territorial land, and the issue relates to jurisdiction over surrounding waters and the Exclusive Economic Zone”[11]. South Korea operates the Ieodo Ocean Research Station on the reef and states that China’s air-defense identification zone (ADIZ) does not affect its use[11].

China also claims jurisdiction over the waters around the rock. The dispute is not about sovereignty but rather about delimiting overlapping EEZs. Both countries have proposed establishing joint research or cooperation zones. As of December 2025, there have been occasional diplomatic protests but no serious confrontations.

Okinotori Reef

Okinotori is a remote atoll about 1,700 km south of Tokyo. Japan contends that the reef is an “island” capable of generating an EEZ and continental shelf. The Japanese government has reinforced the atoll with concrete installations to prevent erosion and maintain habitation claims.

China and South Korea dispute Japan’s classification. In May 2012, Chinese foreign ministry spokesman Hong Lei highlighted that the UN Commission on the Limits of the Continental Shelf did not acknowledge Japan’s claim of an outer continental shelf based on Okinotori[12]. He argued that Okinotori “cannot sustain human habitation” and therefore should not generate an EEZ or continental shelf[12]. China (and South Korea) submitted notes to the UN Secretary‑General stressing that Okinotori should be regarded as a rock with only a 12‑nautical‑mile territorial sea[12]. The issue remains unresolved, and there are occasional incidents where Chinese or Taiwanese fishing boats are detained near the atoll.

Conclusion and outlook

The island disputes among Japan, South Korea and China are unlikely to be resolved soon. Historical memories of colonization, war and national humiliation magnify the stakes. Economic factors—such as fisheries, seabed resources and shipping routes—add practical incentives to maintain claims. In the Senkaku/Diaoyu dispute, both Japan and China are strengthening coastguard capabilities and refusing to compromise, though they occasionally manage tensions through high‑level consultations. The Takeshima/Dokdo conflict remains a major irritant in Japan‑ROK relations despite broader security cooperation. The Northern Territories dispute is frozen due to Russia’s invasion of Ukraine and Japan’s participation in sanctions. In the South China Sea, China’s militarization of islands and rejection of the arbitral ruling continue to provoke pushback from other claimants and the United States.

Nevertheless, there are opportunities for confidence‑building. Negotiating fisheries agreements, joint development of resources and establishing codes of conduct could reduce the risk of clashes. International law, particularly the United Nations Convention on the Law of the Sea, provides mechanisms for peaceful resolution, though states must be willing to accept rulings. Ultimately, progress will require political will to balance nationalist narratives with regional stability and economic cooperation.

Reference list

• Ministry of Foreign Affairs of Japan (MOFA) statements regarding the Senkaku Islands, Takeshima and Northern Territories[1][4][8].
• Republic of Korea Ministry of Foreign Affairs (ROK MOFA) statements on Dokdo, including protests against Japanese textbooks, “Dokdo Day,” and foreign‑minister remarks[5][6][7].
• ROK MOFA press briefing clarifying the status of Ieodo/Socotra Rock[11].
• Chinese government statements on Diaoyu Dao/Senkaku dispute and South China Sea sovereignty[3][2][9].
• Chinese foreign ministry statement rejecting the 2016 arbitral award and defending historic rights in the South China Sea[10].
• Chinese foreign ministry spokesman’s remarks on Okinotori Reef[12].