1.  Historical Developments

3  To support its sovereignty claim, China tends to refer to certain historical events, including the discovery and naming of the islands, and select geographical facts, such as the islands’ location en route to Ryukyu (ie, Okinawa), in addition to writings, documents, and maps of ancient times. It is questionable whether or to what extent these Chinese sources are relevant and/or reliable.

4  On 14 January 1895, the Japanese government decided to erect a marker on Senkaku/Diaoyu to incorporate it formally into the Japanese territory. At that time, China and Japan were at war (‘Sino–Japanese War’ of 1894–1895). The Treaty of Peace between China and Japan to end that war (‘Treaty of Shimonoseki’) was signed, subsequent to Japan’s incorporation of the islands, on 17 April 1895 and entered into force on 8 May 1895. Under Art. 2 of the Treaty, China agreed to cede ‘[t]he island of Formosa [ie, Taiwan], together with all islands appertaining or belonging to the said island of Formosa’ and ‘[t]he Pescadores [ie, Penghu] Group’ to Japan.

5  As a result of its defeat in World War II, Japan lost some of its former territories. Before concluding a peace treaty to end World War II, the major Allied Powers signed several political instruments pertaining to Japan. On 27 November 1943, the United States (‘US’), the United Kingdom (‘UK’), and China (Republic of China [‘ROC’]) signed the Cairo Declaration (General Statement of the Conference of President Roosevelt, Generalissimo Chiang Kai-Shek, and Prime Minister Churchill in North Africa [1943]), which provided that ‘all the territories Japan has stolen from the Chinese, such as Manchuria, Formosa and The Pescadores, shall be restored to the Republic of China’. On 26 July 1945, the US, the UK, and the ROC signed the Potsdam Proclamation Defining Terms for Japanese Surrender, para. 8 of which endorsed the Cairo Declaration by stating that: ‘The terms of the Cairo Declaration shall be carried out and Japanese sovereignty shall be limited to the islands of Honshu, Hokkaido, Kyushu, Shikoku and such minor islands as we determine’. Japan accepted this Proclamation on 14 August 1945, which was then formalized by the Instrument of Surrender signed on 2 September 1945. However, the ultimate peace settlement concerning Japan, including matters related to territories, was not concluded until the Peace Treaty with Japan (1951) of 8 September 1951 (entering into force on 28 April 1952) (‘San Francisco Peace Treaty’).

6  Under the terms of the San Francisco Peace Treaty, Japan ‘renounce[d] all right, title and claim to Formosa and the Pescadores’ (Art. 2 (b)). Japan also agreed to concur with any US proposal to employ the United Nations Trusteeship System, with the US as the sole administering authority, regarding ‘Nansei Shoto south of 29° north latitude (including the Ryukyu Islands and the Daito Islands)’ and some other named islands. Furthermore, Japan accepted, pending a future proposal which was never made, that the US would have the right to exercise ‘all and any powers of administration, legislation and jurisdiction’ over these islands (Art. 3). Although China is not a party to the San Francisco Peace Treaty, the Republic of China (ROC), whose government represented China vis-à-vis Japan at that time, recognized the above disposition of Formosa and the Pescadores in that treaty when it concluded the Treaty of Peace between the Republic of China and Japan on 28 April 1952 (Art. 2) (entering into force on 5 August 1952). On the other hand, the People’s Republic of China (PRC), whose government Japan recognized only on 29 September 1972, has maintained that both the San Francisco Peace Treaty and the Treaty of Peace between the Republic of China and Japan are null and void.

2.  Critical Date and Crystallization of the Dispute over Senkaku/Diaoyu

7  As is true for any territorial dispute, it is important to consider the critical date for the dispute over Senkaku/Diaoyu. As the International Court of Justice (ICJ) pronounced in its judgment in the Territorial and Maritime Dispute between Nicaragua and Honduras in the Caribbean Sea (Nicaragua v Honduras) case in 2007, the significance of a critical date lies in ‘distinguishing between those acts … which are in principle relevant for the purpose of assessing and validating effectivités, and those acts occurring after such critical date, which are in general meaningless for that purpose’ (para. 117). And according to the ICJ judgment in the Sovereignty over Pulau Ligitan and Pulau Sipadan Case (Indonesia/Malaysia) in 2002, a critical date is the date ‘on which the dispute between the Parties crystallized’ (para. 135).

8  After World War II, the US administered Senkaku/Diaoyu de facto initially and then de iure in accordance with Art. 3 San Francisco Peace Treaty. As seen above, Art. 3 of the Treaty provides that ‘the [US] will have the right to exercise all and any powers of administration, legislation and jurisdiction’ over ‘Nansei Shoto … (including the Ryukyu Islands and the Daito Islands)’ among others. On 17 June 1971, it was agreed between Japan and the US that ‘the [US] relinquishes in favor of Japan all rights and interests under Article 3 of [the San Francisco Peace Treaty]’ and ‘Japan … assumes full responsibility and authority for the exercise of all and any powers of administration, legislation and jurisdiction’ over the Ryukyu Islands and the Daito Islands in accordance with Art. I (1) Agreement Concerning the Ryukyu Islands and the Daito Islands (commonly known as the ‘Okinawa Reversion Agreement’), which entered into force on 15 May 1972.

9  Senkaku/Diaoyu was not specifically mentioned in the Okinawa Reversion Agreement, so China consequently denies that Senkaku/Diaoyu was covered by the Agreement. China instead claims that Senkaku/Diaoyu belongs to Taiwan and thus is covered by Art. 2 (b), not Art. 3 San Francisco Peace Treaty. However, China’s contention incorrectly reads the Okinawa Reversion Agreement, which provides in Art. I (2) that the term ‘the Ryukyu Islands and the Daito Islands’ to be returned to Japan means ‘all the territories and their territorial waters with respect to which the right to exercise all and any powers … was accorded to the [US] under Article 3 of the [San Francisco Peace Treaty] other than those with respect to which such right has already been returned to Japan’. The Agreed Minutes attached to the Okinawa Reversion Agreement recorded the understanding of the Parties that the territories defined in Art. I (2) of the Agreement are ‘all of those islands, islets, atolls and rocks situated in an area’ indicated by a list of geographical coordinates in the Minutes, which clearly includes Senkaku/Diaoyu, a fact China does not dispute. Moreover, as part of US Congressional Hearings on the Okinawa Reversion Agreement, a letter dated 20 October 1971 from the Acting Assistant Legal Adviser of the US Department of State clarified that the relevant term in Art. 3 San Francisco Peace Treaty was ‘understood by the [US] and Japan to include the Senkaku Islands’ (at 90).

10  On 30 December 1971, the PRC made its first official claim to sovereignty over Senkaku/Diaoyu and thus a dispute arose between Japan and the PRC. They had begun making unofficial claims to the islands in 1970, including through an article published in China’s State-owned news agency (Xinhua News Agency). The ROC (ie, Taiwan) had presented separate but similar claims to the islands on 11 June 1971. For its part, Japan has maintained that ‘there exists no issue of territorial sovereignty to be resolved concerning the Senkaku Islands’ (see Japanese Foreign Ministry pamphlet ‘The Senkaku Islands: Seeking Maritime Peace based on the Rule of Law, not Force or Coercion’). Thus, the critical date for the dispute over the Senkaku/Diaoyu Islands can reasonably be set for 11 June 1971 (vis-à-vis the ROC) or 30 December 1971 (vis-à-vis the PRC). In this entry, however, events taking place subsequent to these dates will also be discussed as they have territorial and other international law implications.

1.  China

12  As mentioned above, the Chinese (PRC) official position on this issue was articulated for the first time in a ‘Statement of the Ministry of Foreign Affairs of the People’s Republic of China’ of 30 December 1971 (‘China’s Statement of 1971’). It stated that the Senkaku/Diaoyu Islands ‘have been China’s territory since ancient times’ (at 349). According to the Statement, the Senkaku/Diaoyu Islands were ‘already within China’s sea defence areas’ in the Ming dynasty (1368–1644), and they specifically were islands ‘appertaining to China’s Taiwan but not to [Japan’s] Ryukyu’. China held that the Japanese government ‘stole’ Senkaku/Diaoyu during the Sino-Japanese War of 1894–95, and ‘forced [it] to conclude the unequal “Treaty of Shimonoseki” [of 1895]’ (at 350) (see Treaties, Unequal). By that Treaty, the Island of Taiwan together with all islands appertaining or belonging to the Island of Taiwan as well as the Pescadores were ceded to Japan. After World War II, according to China, the Japanese government ‘illicitly handed over to the [US] the Tiaoyu and other islands appertaining to Taiwan’, and the US government ‘unilaterally declared that it enjoyed the so-called “administrative rights” over these islands’, which ‘in itself was illegal’ (at 350). However, as discussed above and below (see paras 9, 16, 17, and 21), it is groundless to argue that the Senkaku/Diaoyu Islands belong to Taiwan.

13  China has recently updated its position on this issue in a white paper of September 2012 (People’s Republic of China State Council Information Office ‘Diaoyu Dao, an Inherent Territory of China’ [2012] [‘China’s White Paper’]). The paper provides more detail than China’s prior arguments, but the thrust of the argument is largely unchanged: it emphasizes the historical bases of China’s claim to the islands. As one of its new detailed arguments, the paper questions the process by which Japan initially incorporated Senkaku/Diaoyu into the Japanese territory. According to China, after secret fact-finding missions to Diaoyu Dao occurred in 1885, the governor of Okinawa Prefecture asked the Japanese Minister for Internal Affairs whether sovereignty markers should be set up there. The central government did not approve this request, following the advice of the Foreign Minister that any such open moves would alert China. The Minister’s recommendation, therefore, was to wait. China’s White Paper of 2012 further notes that around the end of the Sino–Japanese War, Japan secretly made a Cabinet decision to formally place Senkaku/Diaoyu under the jurisdiction of Okinawa Prefecture. Thus, China’s White Paper posits that ‘Japan had consistently acted in secrecy without making its moves public’, leading to its conclusion that ‘Japan’s claim of sovereignty over Diaoyu Dao does not have legal effect under international law’.

14  However, it is a widely shared view that there is no strict legal requirement to notify other States of a government’s intention to occupy terra nullius, as pronounced explicitly in the arbitral award of 1931 concerning the French occupation of Clipperton Island in 1858 (Affaire de l’île de Clipperton [Mexiko v France] 1110; Clipperton Island Arbitration). Moreover, a year after the Cabinet decision, Japan began openly exercising its jurisdiction over Senkaku/Diaoyu, including through the issuance of permits for land tenancy and field surveys by the central government and the government of Okinawa Prefecture. These actions provided external notice to other States that Japan intended to possess sovereignty over the islands.

15  China’s White Paper of 2012 also makes a new salient point in reference to the Cairo Declaration and the Potsdam Proclamation: it argues that

Read together, the Cairo Declaration and the Potsdam Proclamation essentially state that Taiwan should be returned to China. However, these instruments not only lack the status of (full-fledged) legal documents, but also would only be relevant if the Senkaku/Diaoyu Islands were part of Taiwan.

16  As already discussed, Senkaku/Diaoyu is not and has never been part of Taiwan. China inaccurately contends that, pursuant to the Treaty of Shimonoseki, China ceded Senkaku/Diaoyu to Japan as part of its cession of the Island of Taiwan and all other islands appertaining or belonging to the Island of Taiwan. However, as shown in Section B above (para. 4), Japan occupied Senkaku/Diaoyu prior to the conclusion of the Treaty of Shimonoseki. Thus, as China could not transfer more rights than it possessed, it was impossible for China to cede Senkaku/Diaoyu to Japan in that Treaty.

17  Furthermore, there are several instances demonstrating that China acknowledged and recognized Japan’s occupation and incorporation of Senkaku/Diaoyu into the Okinawa Prefecture of Japan. For instance, a letter of appreciation sent from the consul of the Republic of China in Nagasaki in May 1920 regarding Chinese fishermen rescued by Japanese citizens characterized the shores reached as ‘the Senkaku Islands, Yaeyama District, Okinawa Prefecture, Empire of Japan’ (see provisional translation in ‘Senkaku Islands Q&A’). Notably, this letter also provides no indication that China viewed the islands as belonging to or connected with Taiwan. Additionally, an internal Chinese Ministry of Foreign Affairs record of a meeting related to a peace treaty with Japan in 1950 referred to the Senkaku/Diaoyu Islands as the ‘Senkaku Islands’ (the Japanese name) and even mentioned them in the context of Okinawa. In January 1953, an article in the People’s Daily, an organ of the Communist Party of China, explicitly included the Senkaku/Diaoyu Islands among the ‘Ryukyu [ie, Okinawa] Islands’ (see provisional translation in ‘Senkaku Islands Q&A’). These examples (the photographs of the relevant materials can be found in the above-mentioned Japanese Foreign Ministry pamphlet) make clear that China had considered Senkaku/Diaoyu as lawfully belonging to Okinawa, Japan (and thus not Taiwan), which is consistent with China’s long-running silence with regard to anything happening in Senkaku/Diaoyu prior to its assertions in 1970/1971.

18  Finally, whatever implications are drawn from the Cairo Declaration and the Potsdam Proclamation, it is well-established that peace treaties ending wars serve as the final resolution of territorial settlements (Jennings [2017] 86; Oppenheim [1952] 611). In the case of Japan following World War II, this would be the San Francisco Peace Treaty, which deals with Senkaku/Diaoyu (in Art. 3) and Taiwan (in Art. 2) separately (see paras 6 and 9 above). While the PRC opposed the Treaty before and after its conclusion, their reason for doing so—their non-inclusion in the treaty negotiations—was entirely unrelated to the Senkaku/Diaoyu issue. In any case, the Republic of China (ROC), as the legitimate government of China at that time, accepted the territorial disposition made in the San Francisco Peace Treaty by concluding the Peace Treaty between the Republic of China and Japan in 1952 (Arts II and XI).

2.  Japan

19  In its Ministry of Foreign Affairs’ statement entitled ‘The Basic View on the Sovereignty over the Senkaku Islands’ (‘Japan’s Basic View’), issued on 8 March 1972 and revised on 8 May 2013, Japan claims that the government, through the agencies of Okinawa Prefecture, conducted a series of thorough surveys from 1885 to 1895. The results indicated that ‘the Senkaku Islands had been uninhabited and showed no trace of having been under the control of the Qing Dynasty of China [1644–1912]’. According to Japan’s Basic View, the government then made a ‘Cabinet Decision on 14 January 1895 to erect a marker on the Islands to formally incorporate the Senkaku Islands into the territory of Japan’. In 1896, according to the above-mentioned Japanese Foreign Ministry pamphlet entitled ‘The Senkaku Islands’, a Japanese entrepreneur named Tatsushiro Koga obtained permission from the Japanese government to develop the islands, and many Japanese people subsequently moved there. They operated businesses such as dried bonito manufacturing and feather collecting. The government also applied administrative measures such as land surveys and authorizations to run these businesses on the islands. Japan continued to exercise such effective control over Senkaku/Diaoyu until the end of World War II.

20  Japan contends in its Basic View that the Senkaku/Diaoyu Islands have been consistently part of Japan’s territory. They are ‘not included in the islands of Formosa and the Pescadores’, which were ceded to Japan from China in accordance with the Shimonoseki Treaty. At the time of the San Francisco Peace Treaty, therefore, ‘the Senkaku Islands were not renounced by Japan under Article 2 of the Treaty but were placed under the administration of the United States together with other islands of Nansei Shoto in accordance with the provisions of Article 3’ (at 352).

21  Additionally, Japan’s Basic View highlights that ‘[f]or a long time, since the entry into force of the San Francisco Peace Treaty, China [has] raised no objection to the fact that the Senkaku Islands [were] included in the area placed under [US] administration’; it was not ‘until the latter half of 1970 when movements relating to exploitation of oil resources deposited in the East China Sea continental shelf surfaced’ that the PRC and the ROC started to raise questions of sovereignty over Senkaku/Diaoyu. All this, according to Japan, ‘clearly indicate[d] that China had not until recently regarded the Senkaku Islands as a part of Formosa’ (ibid).

22  As the Japanese Ministry of Foreign Affairs explicitly describes in its ‘Senkaku Islands Q&A’, the legal basis of Japan’s possession of, and sovereignty over, the islands under international law is the ‘occupation of terra nullius’. China criticizes such a claim in its White Paper of 2012 by stating that ‘[Diaoyu Dao] is by no means “terra nullius”. China is the indisputable owner of Diaoyu Dao as it had exercised valid jurisdiction over the island for several hundred years long before the Japanese people “discovered” it’. China specifically bases its historical appeal on the islands’ placement under coastal defence in the Ming Dynasty as well as its ‘clearly plac[ing] the islands under the jurisdiction of the local government of Taiwan’ in the Qing dynasty.

23  It must be pointed out, however, that this undoubtedly falls short of the exercise of ‘effective control’ (or effectivité) by China that is required for a valid acquisition of a territory by occupation under modern international law. The arbitral award in the Palmas Island Arbitration (1928) enunciated that modern international law in the 19th century laid down the principle that ‘occupation, to constitute a claim to territorial sovereignty, must be effective’ (at 846). Purely symbolic actions such as drawing a map portraying the islands as within a defence zone or placing the islands under the jurisdiction of local government without actually exercising State function there are insufficient to meet this standard. Notably, neither China’s Statement of 1971 nor its White Paper of 2012 contains any reference to ‘effective’ control over Senkaku/Diaoyu, and they likewise fail to concretely describe the ‘jurisdiction’ under which it claims to have placed the islands. Unless China provides evidence of its exercise of effective control over Senkaku/Diaoyu during the period before Japan’s occupation, the islands properly would have been deemed terra nullius as there was no other claimant.

24  Another major contention by Japan, as seen above, has been that China had expressed no objection to the status of the Senkaku/Diaoyu Islands being under the administration of the US before China began making its own assertions on territorial sovereignty over these islands in 1970/1971. China, nevertheless, counters in its White Paper of 2012 that it has strongly protested against the ‘backroom deals between the [US] and Japan over Diaoyu Dao’ and cites the Chinese government’s statements made in 1951 before and after the conclusion of the San Francisco Peace Treaty to the effect that it is ‘illegal and therefore invalid’. However, it is conspicuous that these 1951 statements did not refer to Senkaku/Diaoyu; instead, the statements repeatedly condemned the preparation, formulation, and signing of the peace treaty without China’s participation. China in fact asserted that the Treaty will be regarded as illegal and invalid, ‘no matter what its content and outcome are’. These statements do not seem to constitute a valid objection for the present purpose, particularly in light of China’s silence on the status of Senkaku/Diaoyu for many years after the conclusion of the Peace Treaty.

3.  United States

25  Despite its admission during the Hearings of the Okinawa Reversion Agreement that Art. 3 San Francisco Peace Treaty is understood ‘to include the Senkaku Islands’, the US has taken a neutral position with regard to the competing Japanese and Chinese claims. The letter from the Acting Assistant Legal Adviser which was shown at the Hearings stated:

The United States believes that a return of administrative rights over those islands to Japan, from which the rights were received, can in no way prejudice any underlying claims. The [US] cannot add to the legal rights Japan possessed before it transferred administration of the islands to us, nor can the [US], by giving back what it received, diminish the rights of other claimants. The [US] … considers that any conflicting claims to the islands are a matter for resolution by the parties concerned (at 91).

26  At the same time, the US position is that Art. V Treaty of Mutual Co-operation and Security between Japan and the US of 1960 applies to Senkaku/Diaoyu. Article V provides that:

The application of Art. V to Senkaku/Diaoyu has been affirmed by successive US administrations, including in the US–Japan Joint Leaders’ Statement ‘US–Japan Global Partnership for a New Era’ of 16 April 2021, in which the US reaffirmed the fact that ‘Article V of the Treaty applies to the Senkaku Islands’. Both leaders also ‘oppose[d] any unilateral action that seeks to undermine Japan’s administration of the Senkaku Islands’.

27  The US position of neutrality regarding the competing claims over Senkaku/Diaoyu could be subject to legal criticism in relation to its use of two of the Senkaku/Diaoyu Islands (Kuba and Taisho Islands) for the purpose of bombing exercises (as an air—to-ground range) during the period of their administration and beyond. Article 3 San Francisco Peace Treaty provides for the right of the US to exercise ‘all and any powers of administration, legislation and jurisdiction’ over the islands.

28  Theoretically, if Japan did not have full sovereignty over Senkaku/Diaoyu, then Japan could only transfer powers it possessed (ie, imperium) to the US in accordance with Art. 3 San Francisco Peace Treaty. Under this assumption, if China had the residual sovereignty (ie, dominium) over Senkaku/Diaoyu, international law would have required the US to obtain permission from China to carry out bombing exercises that could seriously damage the territory. However, there is no record, nor has China presented any evidence, that the US sought (and obtained) Chinese authorization to use these islands for that purpose. This absence of evidence suggests that the legal position of the US logically must have been (and must continue to be) that Japan possesses full sovereignty over Senkaku/Diaoyu.

1.  China’s Enactment of the Law on the Territorial Sea and the Contiguous Zone in 1992

31  In February 1992, China enacted a Law on the Territorial Sea and the Contiguous Zone, which explicitly refers to ‘Diaoyu Island’ as its ‘territorial land’ (Art. 2). This was a new addition as the Declaration of the Government of the PRC on China’s Territorial Sea of 1958 did not include the name in a list of islands.

2.  China’s Dispatch of its Government Ships in 2008 and Ship Crash Incident in 2010

32  In December 2008, two ships belonging to China’s State Oceanic Administration made a sudden entry into the 12–nautical-mile area surrounding Senkaku/Diaoyu, and they hovered and drifted for many hours. Japan perceived these actions as an attempt by China to change the status quo through force or coercion.

33  In September 2010, a Chinese fishing vessel deliberately crashed into Japanese Coast Guard patrol vessels in the 12–nautical-mile area of Senkaku/Diaoyu. The fishing vessel’s captain was arrested and detained, but soon released by the Japanese authorities out of political considerations. This incident led to the deterioration of relations between the two States.

3.  Japan’s Transfer of Ownership of Three Islands to the Government in 2012

34  In April 2012, the Governor of Tokyo announced his plan to buy the three privately-owned islands of Senkaku/Diaoyu (Uotsuri, Kitakojima, and Minamikojima Islands) and to construct dock facilities there. To preempt such a plan in order to ‘maintain and manage the Senkaku Islands peacefully and stably on a long-term basis’, the Japanese government decided to purchase them in September 2012 (see ‘Senkaku Islands Q&A’). While China condemned this as Japan taking ‘unilateral measures’, it does not have any special international legal implications in territorial terms because it was a simple transfer of ownership in accordance with the Japanese domestic Civil Code. In fact, these islands had been owned by the Japanese government until 1932, so the transfer in 2012 was merely a return to this prior position.

35  However, since then, there has emerged a routine pattern whereby Chinese government vessels enter the sea areas surrounding Senkaku/Diaoyu, and the Japanese government lodges a strong protest in response. In 2023, it was recorded that on 42 separate days, Chinese government ships entered into the Japanese-claimed territorial sea surrounding Senkaku/Diaoyu, while the presence of Chinese government vessels in the contiguous zone persisted for 352 days total (<https://fmso.tradoc.army.mil/2024/china-increases-presence-in-east-china-sea-to-change-status-quo/> [accessed 21 October 2024]).

4.  China’s Drawing of Straight Baselines for Senkaku/Diaoyu in 2012

36  In September 2012, China issued a ‘Statement of the Government on the Baselines of the Territorial Sea of Diaoyu Dao and its Affiliated Islands’, setting forth the coordinates of straight baselines for Senkaku/Diaoyu. It also deposited to the United Nations a list of these coordinates and an illustrative chart. However, the straight baselines connecting the islands of Senkaku/Diaoyu are not in conformity with the United Nations Convention on the Law of the Sea (1982) (‘UNCLOS’). According to UNCLOS, such a mode of drawing straight baselines is only allowed for archipelagic States and not for States with offshore archipelagos (South China Sea Arbitration [Philippines v China] [Award] [2016] para. 573; Archipelagic Waters). Moreover, even assuming that the latter kind of States can draw archipelagic straight baselines, the Chinese assertions around Senkaku/Diaoyu fail to satisfy the requirement of Art. 47 (1) UNCLOS concerning the ratio of water to land area enclosed by the baselines. While the UNCLOS requires the ratio to be between 1:1 and 9:1, the Chinese ratio in the Senkaku/Diaoyu area is estimated to be 27.1:1.

37  Japan immediately protested this move by stating: ‘Such unilateral action has no ground under international law including within the [UNCLOS]. This action by the [PRC] concerning the Senkaku Islands, a part of the territory of Japan, is totally unacceptable and legally invalid’ (Permanent Mission of Japan ‘Communication from the Government of Japan to the United Nations [Concerning the Straight Baselines Drawn Around Senkaku Islands]’ [2012]). Japan did not draw straight baselines around these features when it promulgated the 1996 Law on the Territorial Sea and the Contiguous Zone in which Japan introduced the straight baseline system in other contexts for the first time. The United States also sent a diplomatic note to the Chinese government, protesting that the establishment by China of straight baselines around the Senkaku Islands was contrary to customary international law as reflected in the UNCLOS.

5.  Strengthening of the Chinese Maritime and Airspace Patrol Competence: China’s Enactment of the Coast Guard Law in 2021 and Establishment of an Air Defence Identification Zone in 2013

38  The China Coast Guard (‘CCG’) Bureau has been responsible for Chinese maritime law enforcement since its establishment in 2013. In July 2018, the CCG became an integral part of the People’s Armed Police Force and was placed under the unified command of the Central Military Commission, China’s highest national defence organization. Collaboration between the People’s Liberation Army (‘PLA’) and the CCG has also been reinforced in terms of organization, personnel, and equipment, as exemplified by the transfer of retired PLA destroyers and frigates to the CCG.

39  In terms of Chinese legislation, the Coast Guard Law (enacted in January 2021; translations of the law below are by the author) provides that coast guard organizations (including the CCG Bureau and local coast guard bureaus) have the authority to carry out maritime rights enforcement activities in and above the ‘sea areas under the jurisdiction of the People’s Republic of China’. The Law contains no definition or elaboration on this jurisdictional area, but it likely is intended to encompass sea areas surrounding Senkaku/Diaoyu. Article 21 of the Law permits coast guard organizations to take measures, such as forced eviction and forced towing, against ‘foreign military ships and foreign government ships used for non-commercial purposes’ that commit acts in violation of Chinese laws and regulations in the ‘sea areas under [its] jurisdiction’ and refuse orders to leave, thereby causing serious harm or threats. Article 22 further provides that coast guard organizations may take ‘all necessary measures, including the use of arms’ to stop illegal infringement (or imminent danger of such an infringement) on national sovereignty, sovereign rights, and jurisdiction by foreign organizations and individuals at sea. These provisions appear to go beyond permissible conduct under UNCLOS, even within a coastal State’s own territorial seas under Arts 30 to 32.

40  Concerning airspace control, the Chinese Ministry of National Defense established in November 2013 the ‘East China Sea Air Defense Identification Zone’, which includes the airspace above Senkaku/Diaoyu, and issued an ‘Announcement of the Aircraft Identification Rules for the East China Sea Air Defense Identification Zone of the P.R.C.’. Legally, an air defence identification zone (‘ADIZ’) does not carry any territorial implications as it only serves to protect the coastal State from unwanted intruders (Air Defence Identification Zones). The State administering the ADIZ normally requires foreign civil aircraft to provide it with advance warning information only if the aircraft’s final destination is the said State or the aircraft otherwise intends to enter its airspace. However, China requires aircraft (civil or military) flying in its East China Sea ADIZ (regardless of the aircraft’s final destination) to abide by the announced Rules, including requirements to furnish identification. The Rules also provide that aircraft flying in the East China Sea ADIZ should follow the instructions of the Ministry of National Defense. Most notably, China warns in the Rules that aircraft failing to cooperate in the identification or refusing to follow the instructions would face unspecified ‘defensive emergency measures’ by the Chinese armed forces. It was also reported early in 2024 that China constantly deployed multiple warships and patrol vessels near the borders of its ADIZ and sometimes warned Japanese Maritime Self-Defense Force aircraft flying over the Senkaku area to leave (<https://japannews.yomiuri.co.jp/politics/defense-security/20240128-165250/> [accessed 21 October 2024]).

41  Japan’s Foreign Minister responded by expressing deep concern that China’s establishment of this zone constituted a profoundly dangerous act that unilaterally changed the status quo in the East China Sea. He also criticized the announced ‘defensive emergency measures’ as ‘unduly infring[ing] the freedom of flight in international airspace, which is the general principle of international law’ (Japanese Ministry of Foreign Affairs ‘Statement on the Announcement on the “East China Sea Air Defense Identification Zone” by the Ministry of National Defense of the People’s Republic of China’ [2013]) (Airspace). Specific concern was directed at the seeming description of the airspace over the Senkaku/Diaoyu Islands as if it were a part of China’s ‘territorial airspace’, which ‘Japan cannot accept at all’. All these unilateral measures taken by China in both airspace and sea areas appear to complicate future resolution of the dispute.

Cited Bibliography

• L Oppenheim International Law vol 2 Disputes, War and Neutrality (H Lauterpacht (ed) 7th edn Longmans London 1952).

• RY Jennings The Acquisition of Territory in International Law (2nd edn Manchester University Press Manchester 2017).

Further Bibliography

• C-H Park ‘Oil under Troubled Waters: The Northeast Asia Sea-Bed Controversy’ (1973) 14 HarvIntlLJ 212–60.

• T Cheng ‘The Sino-Japanese Dispute over the Tiao-yu-tai (Senkaku) Islands and the Law of Territorial Acquisition’ (1974) 14 VaJIntlL 221–66.

• VH Li ‘China and Off-Shore Oil: The Tiao-yì Tai Dispute’ (1975) 10 StanJIntlL 143–62.

• KT Chao ‘East China Sea: Boundary Problems Relating to the Tiao-yu-t’ai Islands’ (1982) 2 Chinese Yearbook of International Law and Affairs 45–97.

• Y Matsui ‘International Law of Territorial Acquisition and the Dispute over the Senkaku (Diaoyu) Islands’ (1997) 40 JapanAnnIntlL 3–31.

• Taiwan Law Society and Taiwan Institute of International Law (eds) International Law Conference on the Dispute over Diaoyu/Senkaku Islands (Taiwan Law Society and Taiwan Institute of International Law Taipei 1997).

• U Suganuma Sovereign Rights and Territorial Space in Sino-Japanese Relations: Irredentism and the Diaoyu/Senkaku Islands (University of Hawaii Press Honolulu 2000).

• S Lee ‘Territorial Disputes among Japan, China and Taiwan Concerning the Senkaku Islands’ (2002) 3(7) Boundary & Territory Briefings 1–30.

• J Shen ‘China’s Sovereignty over the South China Sea Islands: A Historical Perspective’ (2002) 1(1) Chinese Journal of International Law 94–157.

• TJ Schoenbaum ‘Resolving Japan’s Territorial and Maritime Disputes with Its Neighbors: Problems and Opportunities’ (2006) 57 The Journal of Social Science of the International Christian University in Japan 197–254.

• H-Y Shaw ‘Revisiting the Diaoyutai/Senkaku Islands Dispute: Examining Legal Claims and New Historical Evidence under International Law and the Traditional East Asian World Order’ (2008) 26 Chinese (Taiwan) Yearbook of International Law and Affairs 95–168.

• R Drifte ‘The Senkaku/Diaoyu Islands Territorial Dispute between Japan and China: Between the Materialization of the China Threat and Japan Reversing the Outcome of World War II?’ (2013) 32 UNISCI Discussion Papers 9–62.

• Y Matsui ‘Between History and International Law: Senkaku/Diaoyu Dispute Revisited’ (2014) 113(2) Journal of International Law and Diplomacy 145–68.

• RM Scoville ‘A Defense of Japanese Sovereignty over the Senkaku/Diaoyu Islands’ (2014) 46 GWashIntLRev 571–605.

• X Zhang ‘Diaoyu/Senkaku Dilemma: To Be or Not to Be’ (2014) 113(2) Journal of International Law and Diplomacy 169–92.

• M Asada ‘The Senkaku/Diaoyu Islands Issue and Confidence-Building in the East China Sea’ in C Schofield YK Park and L Bernard (eds) East China Sea: How to Build Confidence and Promote Cooperation (Korea Maritime Institute Busan 2017) 49–75.

• ME Manyin ‘The Senkakus (Diaoyu/Diaoyutai) Dispute: U.S. Treaty Obligations’ (2021) US Congressional Research Service Report 1–12.

• S Sakamoto ‘Anatomy of China’s Maritime Strategy: Threatening the Maritime Order Through Its National Legislation and Self-Centered Interpretation of UNCLOS’ (2023) 100 International Law Studies 374–402.

• K Serita The Territory of Japan: Its History and Legal Basis (2nd edn Springer 2023).

Cited Documents

• Agreement Concerning the Ryukyu Islands and the Daito Islands (with agreed minutes and exchanges of notes) (signed 17 June 1971, entered into force 15 May 1972) 841 UNTS 249 (Okinawa Reversion Agreement).

• Coast Guard Law of the People’s Republic of China (promulgated 22 January 2021, entered into force 1 February 2021), available at <https://www.msa.gov.cn/page/article.do?type=hsfg&articleId=37cb1e19580b4f62acea63b76d056d97> (accessed 25 August 2024).

• General Statement of the Conference of President Roosevelt, Generalissimo Chiang Kai-Shek, and Prime Minister Churchill in North Africa (27 November 1943) IX (232) Dept St Bull 393 (Cairo Declaration).

• Instrument of Surrender by Japan (signed 2 September 1945) in CI Bevans (ed) Treaties and Other International Agreements of the United States of America vol 3 Multilateral Treaties 1931–1945 (US Government Printing Office Washington DC 1969) 1251–53.

• Joint Communiqué of the Government of Japan and the Government of the People’s Republic of China (29 September 1972), available at <https://www.mofa.go.jp/region/asia-paci/china/joint72.html> (accessed 25 August 2024).

• Law on the Territorial Sea and the Contiguous Zone (adopted 25 February 1992) (People’s Republic of China), available at <https://www.un.org/depts/los/LEGISLATIONANDTREATIES/PDFFILES/CHN_1992_Law.pdf> (accessed 25 August 2024).

• Law on the Territorial Sea and the Contiguous Zone (Law No 30 of 1977, as amended by Law No 73 of 1996) (Japan), available at <https://www.un.org/depts/los/LEGISLATIONANDTREATIES/PDFFILES/JPN_1996_Law.pdf> (accessed 25 August 2024).

• Ministry of Foreign Affairs of Japan ‘The Basic View on the Sovereignty over the Senkaku Islands’ (8 March 1972) in JA Cohen and H Chiu (eds) People’s China and International Law: A Documentary Study vol I (Princeton University Press Princeton 1974) 351.

• Ministry of Foreign Affairs of Japan ‘The Basic View on the Sovereignty over the Senkaku Islands’ (revised 8 May 2013) available at <https://www.mofa.go.jp/region/asia-paci/senkaku/basic_view.html> (accessed 25 August 2024).

• Ministry of Foreign Affairs of Japan ‘Senkaku Islands Q&A’ (March 2013), available at <https://www.mofa.go.jp/region/asia-paci/senkaku/qa_1010.html#q6> (accessed 25 August 2024).

• Ministry of Foreign Affairs of Japan ‘Statement on the Announcement on the “East China Sea Air Defense Identification Zone” by the Ministry of National Defense of the People’s Republic of China’ (24 November 2013), available at <https://www.mofa.go.jp> (accessed 25 August 2024).

• Ministry of Foreign Affairs of Japan ‘The Senkaku Islands: Seeking Maritime Peace based on the Rule of Law, not Force or Coercion’ available at <https://www.mofa.go.jp> (accessed 25 August 2024).

• People’s Republic of China ‘Declaration of the Government of the People’s Republic of China on China’s Territorial Sea’ (4 September 1958) in United Nations The Law of the Sea: Baselines: National Legislation with Illustrative Maps (United Nations 1989) 104.

• People’s Republic of China ‘Statement of the Government of the People’s Republic of China on the Baselines of the Territorial Sea of Diaoyu Dao and Its Affiliated Islands’ (10 September 2012), available at <https://www.un.org/depts/los/LEGISLATIONANDTREATIES/PDFFILES/DEPOSIT/chn_mzn89_2012_e.pdf> (accessed 25 August 2024).

• People’s Republic of China Ministry of National Defense ‘Announcement of the Aircraft Identification Rules for the East China Sea Air Defense Identification Zone of the P.R.C.’ (23 November 2013), available at <https://web.archive.org/web/20131128215834/http://eng.mod.gov.cn:80/Press/2013-11/23/content_4476143.htm> (accessed 25 August 2024).

• Permanent Mission of Japan ‘Communication from the Government of Japan to the United Nations (Concerning the Straight Baselines Drawn Around Senkaku Islands)’ (24 September 2012), available at <https://www.un.org/depts/los/LEGISLATIONANDTREATIES/PDFFILES/DEPOSIT/communicationsredeposit/mzn89_2012_jpn.pdf> (accessed 25 August 2024).

• Proclamation Defining Terms for Japanese Surrender (26 July 1945) in CI Bevans (ed) Treaties and Other International Agreements of the United States of America 1776–1949 vol 3 Multilateral Treaties 1931–1945 (US Government Printing Office Washington DC 1969) 1204 (Potsdam Proclamation).

• State Council Information Office of the People’s Republic of China ‘Diaoyu Dao, an Inherent Territory of China’ (25 September 2012), available at <http://www.scio.gov.cn/zfbps/ndhf/2012n/202207/t20220704_130081.html> (accessed 25 August 2024) (China’s White Paper).

• ‘Statement of the Ministry of Foreign Affairs of the People’s Republic of China’ (30 December 1971) in JA Cohen and H Chiu (eds) People’s China and International Law: A Documentary Study (Princeton University Press Princeton 1974) 349–51.

• Treaty of Mutual Co-operation and Security (signed 19 January 1960, entered into force 23 June 1960) 373 UNTS 179.

• Treaty of Peace and Friendship between Japan and the People’s Republic of China (signed 12 August 1978, entered into force 23 October 1978) 1225 UNTS 257.

• Treaty of Peace between China and Japan (signed 17 April 1895, entered into force 8 May 1895) 181 CTS 217 (Treaty of Shimonoseki).

• Treaty of Peace between the Republic of China and Japan (signed 28 April 1952, entered into force 5 August 1952) 138 UNTS 38.

• Treaty of Peace with Japan (signed 8 September 1951, entered into force 28 April 1952) 136 UNTS 45 (San Francisco Peace Treaty).

• United Nations Convention on the Law of the Sea (concluded 10 December 1982, entered into force 16 November 1994) 1833 UNTS 3.

• US–Japan Joint Leader’s Statement ‘US–Japan Global Partnership for a New Era’ (16 April 2021), available at <https://www.whitehouse.gov> (accessed 25 August 2024).

• US Senate ‘Hearings Before the Committee on Foreign Relations’ Agreement Between the United States of America and Japan Concerning the Ryukyu Islands and the Daito Islands (27, 28 and 29 October 1971) (US Government Printing Office Washington 1971), available at <https://riis.skr.u-ryukyu.ac.jp> (accessed 25 August 2024).

Cited Cases

• Affaire de l’île de Clipperton (Mexiko v France) (28 January 1931) (1949) 2 RIAA 1105.

• Island of Palmas (Netherlands v United States of America) (4 April 1928) (1949) 2 RIAA 829.

• South China Sea Arbitration (Philippines v China) (Award) (12 July 2016) PCA Case No 2013-19.

• Sovereignty over Pedra Branca/Pulau Batu Puteh, Middle Rocks and South Ledge (Malaysia/Singapore) (Judgment) [2008] ICJ Rep 12.

• Sovereignty over Pulau Ligitan and Pulau Sipadan (Indonesia/Malaysia) (Judgment) [2002] ICJ Rep 625.

• Territorial and Maritime Dispute between Nicaragua and Honduras in the Caribbean Sea (Nicaragua v Honduras) (Judgment) (8 October 2007) [2007] ICJ Rep 659.