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Beyond Boundaries | China's Deployment of Gray Zone Tactics against Japan and the Philippines


Instances of Chinese naval forces behaving unprofessionally at best and outright dangerously at worst have been well-recorded over the last years. In November 2023, the use of sonar pulses by a Chinese warship injured multiple Australian sailors on an Australian vessel operating in Japanese waters just days before Prime Minister Albanese was to meet Xi Jinping and discuss a revitalization of the bilateral relationship (Needham, 2023). Official and unofficial Chinese maritime units also register frequent run-ins with the maritime law enforcement agencies of countries such as Indonesia, Japan, Malaysia, the Philippines, South Korea, Taiwan, and Vietnam. As Chinese strategic behavior has become more volatile and less risk-averse, maritime tensions in East Asia have steadily increased. 

Chinese maritime operations are frequently argued to be located in the ‘gray zone’ between peace and conflict: although the activities are hostile in nature, they do not cross the line to a degree that would justify an outright military action. In this context, this article understands gray zone tactics as “coercive Chinese government geopolitical, economic, military, and cyber and information operations (cyber/IO) activities beyond regular diplomatic and economic activities and below the use of kinetic military force” (Lin et al., 2022). The broader use of this strategy is shaped by domestic legislation that allows China to use theoretically non-State-owned assets, China’s growing economic and military power in relation to other regional actors, and the increased blending of military and paramilitary forces (Lin et al., 2022). In the maritime context, the deployment of gray zone tactics is directly linked with China’s assertion of maritime claims in the East China Sea and the South China Sea. For Beijing, the use of gray zone tactics ultimately aims “to exert authority over a maritime space using civilian craft and personnel, but doing it in a way that precludes open military confrontation [...] activities are consciously kept below the threshold of conflict, yet demonstrate China’s resolve to establish control over disputed features” (Singh, 2018, p. 2). 

Taking the concept of gray zone tactics as a starting point, this submission investigates how China has deployed these tactics in two empirical cases: Japan and the Philippines. More specifically, it will examine the Sino-Japanese dispute surrounding the Senkaku Islands in the East China Sea and the wider maritime dispute linked with Beijing’s ‘nine-dash line’ in the South China Sea. While the conflict in the South China Sea involves a variety of actors, the escalatory potential has been highest in the case of the Philippines. The article first examines the case of Japan and then that of the Philippines, highlighting that China has used gray zone tactics to project power and assert authority. However, the use of these tactics has in both cases driven an attempt to expand indigenous capabilities and strengthen security relationships with other partners. The article concludes that the study of gray zone tactics by China is crucial for countries in the Indo-Pacific, including in South Asia, that are tasked with responding to an increasingly hostile China. 


Japan and the East China Sea

The Japan-China maritime dispute in the East China Sea has deep historical roots that are linked to overlapping territorial claims in the region and associated historical grievances. The focal point of the dispute is the Senkaku Islands archipelago (Diaoyu Islands in Chinese), a group of uninhabited islets and rocks situated between the northern tip of Taiwan and the Okinawa archipelago. The area around the islands is also home to the Chunxiao gas field (Shirabaka in Japanese, see Figure 1), which is situated around the formal intersection between the Chinese and Japanese Exclusive Economic Zones (EEZs) in which claimant countries have exclusive drilling rights (U.S. Energy Information Administration, 2014). The era of the Senkaku Islands also expands Japan’s Air Defense Identification Zone (ADIZ), in which countries identify and locate aircraft to safeguard their airspace, ensure early detection, and respond to potential threats.


Figure 1: China’s and Japan’s AIDZs and EEZs in the East China Sea
Source: Marcus (2013)

As with other maritime and territorial disputes, China bases its claim to the Senkaku Islands on the supposed control of the area by past Chinese polities. In this, Chinese representatives cite historical documents, such as maps and official records, to support the claim that the islands were historically part of Chinese territory under the Ming and Qing dynasties (1368-1912) (Hamakawa, 2007). In 1895, the Qing dynasty ceased sovereignty over the islands in the Treaty of Shimonoseki, signed following the defeat by China against Japan in the first Sino-Japanese war. Following their accession to Japan, the islands were formally administratively incorporated into Japanese territory. After Japan's surrender at the end of the Second World War in 1945, the Chinese Republican government of Chiang Kai-shek, which had fought against Japan since 1937 and had cooperated with the allied war effort against the Japanese Empire, claimed that the Potsdam Declaration and the Cairo Declaration called for the return of territories, including the Senkaku Islands, which were taken by Japan through aggression (Chiba, 2021). Following the war, however, the United States initially took administrative control of the Senkaku Islands before returning them to Japanese administrative control in 1972 as part of the Okinawa reversion, which re-established Japanese sovereignty over the Okinawa archipelago. Beijing protested this decision, highlighting that it had not been consulted on matter and arguing that Washington should not have included the disputed islands in the reversion (Chiba, 2021). In sum, China views Japan’s control over the islands as a violation of its territorial integrity.

Military tensions surrounding the islands began increasing significantly in the early 2010s. On September 7, 2010, a Chinese trawler collided with two Japanese Coast Guard (JCG) vessels near the Senkaku Islands in Japanese waters. The JCG unit then detained the Chinese trawler captain, which led China to demand the immediate release of the captain (Rathus, 2010). Reflecting the broader stream of anti-Japanese sentiments in contemporary China, anti-Japanese protests erupted in various Chinese cities (Al Jazeera, 2010). China also halted the export of rare-earth minerals to Japan and imposed unofficial trade sanctions on Japanese firms (Rachman, 2023). In September 2012, tensions increased further as the Japanese government under Prime Minister Noda Yoshihiko decided to nationalize three of the disputed islands by acquiring them from their private Japanese owners, thus reinforcing more complete administrative control by Tokyo (Johnstone, 2022). The islands’ nationalization led to a significant escalation in tensions between China and Japan, with Beijing arguing that the move was a violation of China's territorial integrity and sovereignty. In response, various bilateral meetings and events were postponed or canceled while anti-Japanese protests erupted again (Zhang, 2015). Whilst the dispute did not originate in the 2010s, the events in 2010 and 2012 marked inflection points that significantly increased tensions surrounding the dispute. 

Since then, China has ramped up the use of gray zone tactics surrounding the Senkaku Islands to project power in the region without crossing the threshold of open conflict. China has intensified its maritime patrols around the islands via the deployment of Chinese Coast Guard (CCG) vessels and maritime law enforcement ships to assert its claims while the People’s Liberation Army Navy (PLAN), the party-State’s naval force, has also engaged in repeated maneuvers and exercises surrounding the islands (Patalano, 2020). Another key asset has been the maritime militia, which is “a force of vessels ostensibly engaged in commercial fishing but which in fact operate alongside Chinese law enforcement and military to achieve political objectives in disputed waters” (Poling et al., 2021). The simultaneous deployment of the CCG, the PLAN, and the maritime militia highlights Beijing’s multidimensional approach to asserting its maritime claims in the area, with the maritime militia also being designed to ensure a degree of plausible deniability. In this context, potential incidents between Japanese units and formally civilian Chinese vessels can then be blamed on Tokyo, sustaining a narrative in which Japan aggravates tensions. Further, China has deployed unmanned aerial vehicles (UAVs) to conduct surveillance and reconnaissance operations in the East China Sea and monitor the activities of Japanese units (Choi, 2023). China has also declared an ADIZ over the Senkaku Islands (which then formally overlaps with Japan’s ADIZ, see Figure 1) (Burke & Cevallos, 2017). Notably, China only announced this ADIZ in 2013, indicating that it views the declaration of ADIZs as another tool to project power. Since then, Chinese military aircraft have routinely violated Japan’s ADIZ surrounding the Senkaku Islands, illegally entering the Japanese ADIZ a total of 675 times in 2019 alone (Axe, 2020). ADIZ incursions are part of China’s broader gray zone repertoire in the East China Sea that is also frequently employed against Taiwan (Tsui, 2022). As Japan has pushed back against Chinese claims, China has ultimately ramped up its use of gray zone tactics in disputed areas.

Japan has responded to the expanding scope of Chinese gray zone operations in the East China Sea with a combination of diplomatic, military, and law enforcement measures. Maritime patrols of the JCG and the Maritime Self-Defense Force (MSDF), Japan’s navy, have expanded and investments in naval security units have increased as threat perceptions have been aggravated (Dominguez, 2023). Tokyo has also sought to boost its intelligence-gathering capabilities, including by ramping up surveillance and reconnaissance activities in the East China Sea and deepening cooperation with regional allies and partners, most notably the United States. Over the last years, different Japanese administrations have enacted domestic security legislations and revised extant defense guidelines to enhance their ability to respond to security challenges, including gray zone threats (Kraska, 2020). Further, Japan has invested in capacity building and infrastructure development on its peripheral islands. The investment in indigenous capabilities has subsequently emerged as a more pressing security priority as Japan aims to develop policy responses to Chinese incursions. 

In terms of its external balancing behavior, Japan has taken significant steps to deepen its security relationship with the United States since the 2010 incident. In 2015, the administration of Prime Minister Abe Shinzo revised the Japan-US bilateral defense guidelines. These revisions expanded the scope of cooperation to include new domains such as space and cyberspace but also suggested that Japan would militarily support US military action abroad even if no immediate threat to the Japanese islands existed (Schoff, 2015). The 2015 revision was widely viewed as opening the door to a participation of Japanese forces in a potential Taiwan contingency (Ashley, 2021). A year later, Japan and the United States renegotiated the Host Nation Support Agreement, leading to Japan heightening its financial contribution to the maintenance of the US troop presence in the country (Tatsumi, 2016). These steps in the bilateral relationship do not just reflect Washington’s growing demands for Japan’s emergence as a greater security stakeholder but a firm recommitment to the bilateral alliance between Japan and the United States. 

Japan has also deepened its defense cooperation with regional partners other than the US. This includes participation in forums such as the Quadrilateral Security Dialogue (Quad) involving the United States, Australia, and India. Defense cooperation agreements and dialogues with countries like Australia, the United Kingdom, and France have been pursued to strengthen security ties and promote regional stability. Japan has additionally increased its security engagement with countries in Southeast Asia, including by recently loosening restrictions on defense exports and the use of Japanese development aid to fund the development of military infrastructure (Murakami, 2023). Besides its relationship with the United States, Japan has thus actively sought to develop regional frameworks that ensure broader coordination activities between regional stakeholders. 

Lastly, Japan has announced a highly ambitious military modernization program. In 2022, Prime Minister Kishida Fumio announced that the military budget would be doubled to 2% of the GDP over the next five years, including allocations for research and development, the procurement of advanced equipment, and the maintenance of existing capabilities (McCurry, 2022). Japan has been enhancing its amphibious and rapid deployment capabilities, focusing on the capacity to respond swiftly to security challenges, including those on remote islands. This involves the creation of an amphibious rapid deployment brigade within the Japanese Self-Defense Force (JSDF) and the acquisition of amphibious assault vehicles and related equipment. Lasty, the Japanese military is planning for the acquisition of counter-strike capabilities that could attack stationary targets abroad, including in China and North Korea, and significantly enhances the long-range offensive military capacities of the military (Hirao & Sasaki, 2023). This historic military build-up in a country that has long been viewed as synonymous with Pacifism indicates the deterioration of the security environment in East Asia as tensions with China escalate. 

On the trade front, China’s weaponization of trade relations in the early 2010s has sparked a significant rethinking surrounding economic vulnerabilities and has driven an attempt to reduce economic dependencies on China. Japan has actively sought to create more resilient and diversified supply chains by establishing alternative suppliers, both within and outside of Asia.  In response to the rare earth ban of 2010, for instance, Tokyo provided funds for Japanese firms to discover new sourcing markets, and the dependence of national firms on Chinese rare earth imports has decreased since then (Rachman, 2023). The government has encouraged companies to reassess and reorganize their supply chains to ensure continuity in the face of disruptions, including pandemics and growing geopolitical tensions. As part of this, Japan has encouraged the reshoring of companies from China via tax incentives and subsidies to companies that relocate to Japan or expand their manufacturing operations within Japan (Nagy, 2023). Funding has also been made available to incentivize the diversification of firms’ operations, most notably to Southeast Asia (Abe, 2020). Japan’s support for an even deeper economic relationship with Southeast Asia can also be seen in its support for regional free trade agreements, including the Comprehensive and Progressive Agreement for Trans-Pacific Partnership (CPTPP), which followed on the Trans-Pacific Partnership, and the Regional Comprehensive Economic Partnership (RCEP). While the notion of de-risking has become prominent in Western countries since the outbreak of the COVID-19 pandemic, Japan has arguably sought to de-risk its economy from China since the early 2010s. 


The Philippines and the South China Sea

The Philippines is one of a number of claimant States in Southeast Asia that are affected by what is known as the ‘nine-dash line’, which demarcates China’s maritime claims over effectively all of the South China Sea. The origins of the nine-dash line can be traced back to the mid-20th century, when the Republic of China (ROC), the predecessor to the current government in Taiwan, first officially published a map featuring the claims in the late 1940s. After the Chinese Communist Party came to power in 1949, the People's Republic has continued to assert the validity of the nine-dash line. As Figure 2 highlights, China claims effectively all of the South China Sea – a clear violation of the United Nations Convention on the Law of the Sea (UNCLOS), the main legal international framework defining the rights and responsibilities of States in maritime areas. In its current form, the nine-dash line infringes on the EEZs of Brunei, Indonesia, Malaysia, the Philippines, and Vietnam. For the Philippines, the disputed areas concern the northeastern part of the Spratly Islands as well as the Scarborough Shoal, which Manila calls the Bajo de Masinloc and Beijing names Huangyan Island, off the western coast of Luzon (National Bureau of Asian Research, n.d.). 

Figure 2: The Spratlys and the Scarborough Shoal
Source: BBC (2023)

After Chinese-Filipino tensions surrounding the Spratlys and the Scarborough Shoal intensified in the early 2010s, the Philippines initiated arbitration proceedings against China under UNCLOS at the Permanent Court of Arbitration in The Hague. In October 2011, a Philippine naval vessel collided with a Chinese fishing boat close to Reed Bank in parts of the Spratlys claimed by Manila. In 2012, a diplomatic standoff between both countries ensued as Chinese fishing boats crowded the Scarborough Shoal, leading to the Philippines deploying a warship and maritime patrol vessels to the area. Amid repeated Chinese incursions and the growing usage of gray zone tactics by Beijing, the Philippine government of President Benigno Aquino III then lodged a complaint to the Permanent Court of Arbitration to clarify the maritime entitlements of both countries in the South China Sea and challenge the validity of the nine-dash line claim made by China. Beijing rejected the arbitration process from the outset, asserting that it would not participate, and that the tribunal lacked jurisdiction. Instead, Beijing proposed, maritime disputes in the South China Sea should be resolved through direct negotiations with the concerned parties. This focus on bilateral negotiations has been replicated by China elsewhere and serves to undermine the potential collective bargaining positions by other claimants in regional fora, such as the Association for Southeast Asian Nations (ASEAN) (Vu, 2023). In 2016, the arbitral tribunal delivered its ruling, concluding that China's nine-dash line had no legal basis and did not grant any maritime rights. The tribunal also found that certain features claimed by China, such as Mischief Reef and the Second Thomas Shoal, were low-tide elevations and not islands. China's actions, including the construction of artificial islands, were deemed to have caused irreparable harm to the marine environment and violated the Philippines' sovereign rights (Graham, 2016). Furthermore, the tribunal ruled that China's activities, particularly its construction of artificial islands and interference with Philippine fishing and oil exploration activities, violated UNCLOS. In line with its previous rhetoric, China promptly rejected the tribunal's decision, stating that it was null and void, and that it would not affect China's territorial sovereignty and maritime rights. 

In practice, China’s usage of gray zone tactics in disputes with the Philippines continued and intensified after the verdict, demonstrating the ruling’s lack of material effects. China continued to assert its presence in the South China Sea through the continued incremental militarization of disputed features, including the expanding construction and reinforcement of artificial islands with military facilities (Leplâtre, 2023). Coercive tactics also included the restriction of access to traditional fishing grounds of Filipino fishermen through the CCG and the maritime militia (Bhandari, 2023). In this context, China’s insistence on bilateral negotiations weakened Manila’s bargaining position. At the same time, China continued partaking in diplomatic initiatives, such as discussions on a Code of Conduct (COC) in the South China Sea with ASEAN countries (Parameswaran, 2023). By engaging in these forums, China has sought to project an image of itself as a cooperative regional actor. This aspirational portrayal remained disconnected from the reality on the ground as China ramped up its use of gray zone tactics. 

The relatively pro-China position of Aquino’s successor Rodrigo Duterte, who entered office in 2016, nevertheless meant that China’s growing assertiveness resulted in a significant deterioration in the Beijing-Manila relationship as Duterte remained eager to secure Chinese investments in the Philippines. Duterte initially adopted a confrontational and anti-US rhetoric, expressing discontent with what he perceived as interference in the country’s domestic affairs, especially in regard to US criticism toward Duterte’s ‘war on drugs’ (BBC, 2016), which involved the State-sanctioned killing of alleged drug users and distributors by security and paramilitary forces (Zhang, 2023). After the US declined to provide a visa to Ronald dela Rosa, Duterte’s previous police chief and the primary implementer of his violent anti-drug campaign, Duterte threatened to terminate the Visiting Forces Arrangement (VFA), which permits for the rotational stationing of US troops in the Philippines in line with the Philippines-US mutual defense treaty of 1950 (The Guardian, 2020). The deterioration of the Manila-Washington relationship was accompanied by a simultaneous improvement of the relations with China. Duterte actively courted Chinese investments in major infrastructure projects, such as railways and ports, under China's Belt-and-Road Initiative (BRI) during bilateral meetings and a State visit to China (Strangio, 2020). Duterte also largely ignored the 2016 arbitral ruling on the South China Sea even as China ramped up its illicit activities in the region (Grossman, 2023). The President’s populist policy approach thus reshaped the Philippines’ strategic environment by threatening the long-standing relationship with the United States and providing for greater economic dependence on China. 

In the last years of his Presidency, Duterte tacitly reversed course as the Chinese use of gray zone tactics expanded even as the trade and investment relationship with the Philippines improved. Since Duterte had come into power, China had continued to expand its footprint in the region by encircling the Manila-administered Thitu Island with militia boats, permitting CCG vessels to attack non-Chinese ships in the region, and stationing hundreds of militia boats surrounding the disputed Whitsun Reef (Grossman, 2023). In response, Duterte went on to recognize the 2016 ruling of the Permanent Court of Arbitration before canceling his plans to end the VFA with the United States (Grossman, 2023). The ultimate failure of Duterte’s appeasement approach toward China ultimately highlighted the limits of a foreign policy strategy that sought to reduce the emphasis on tensions by stressing the potential commercial benefits of the bilateral relationship while ignoring Manila’s legitimate security concerns. 

Under Duterte’s successor Ferdinand ‘Bongbong’ Marcos Jr., who replaced Duterte in 2022 and is the son of the former military dictator Ferdinand Marcos Sr., the Philippines has reoriented its policy position toward its traditional alliance with the United States. To be sure, Bongbong Marcos has partially continued Duterte’s broader hedging strategy by seeking to attract investment from China, negotiating over shared oil and gas exploration projects, and rhetorically committing his administration to an “independent foreign policy” also promoted by Duterte (Lischin, 2022). However, Marcos’ signaling was more overtly pro-Washington than Duterte’s often volatile rhetoric had been; during a visit of US Vice President Kamala Harris to the Philippines in November 2022, Marcos stated that “I do not see a future for the Philippines that does not include the United States” (Beltran, 2022). The growing proximity with the United States is directly related with a deepening Chinese assertiveness in disputes in the South China Sea; patrols by CCG vessels increased over 2022 and in February 2023, the CCG aimed a “military-grade laser” at Philippine resupply vessels around the Second Thomas Shoal (Grossman, 2023). In early December 2023, Philippine forces initially accused Chinese vessels of attacking them with water cannons - a day later, a Chinese and a Philippine vessel collided, with an official statement by the Philippines accusing China of having “harassed, blocked, and executed dangerous maneuvers" (Wright, 2023). Tensions, then, have remained high and have expanded rather than ameliorating. 

As with Japan, the Marcos government has responded to the expansion of Chinese activities by ramping up investments in indigenous capabilities and strengthening its security relationships with other regional actors. Manila has published an ambitious military modernization program that plans for the acquisition of multi-role fighter aircraft, helicopters, radar equipment, additional frigates, submarines, India-produced BrahMos cruise missile systems and the US-developed High Mobility Artillery Rocket Systems (HIMARS) that has been effectively used by the Ukrainian armed forces since Russia’s invasion of Ukraine (Saballa, 2023). The government has also doubled down on its relationship with Washington, including through the planned launch of a trilateral defense arrangement with Japan and the US (Ashley, 2023). The relationship with India has improved due to shared regional interests and close defense industry cooperation most recently evidenced by the Philippines’ purchase of the BrahMos cruise missiles (Chalk, 2023). Lastly, Manila’s relationship with Canberra has become deeper as security cooperation expanded in the wake of China’s assertive behavior in the South China Sea throughout the 2010s (Baquisal, 2023). Although the Philippines has largely continued its hedging approach and remains keen to not openly antagonize China, there is a clearer diplomatic position discernible that has been backed by growing capacities and enhanced cooperation with regional partners.

China’s continued violations of international law and the subsequently growing alienation of countries in Southeast Asia are the key causal factors driving closer cooperation between regional countries and the United States. For China, collaboration between the United States and the Philippines (and other Southeast Asian countries) are rooted in regional actors subordinating to US hegemony - as a result of this cognitive framing, any action taken by China merely constitutes a response and has no causal impact on how foreign policy is developed and implemented in Southeast Asia. As Gregory Poling and Jude Blanchette (2023) from the Center for Strategic and International Studies eloquently formulate, however,

“Beijing is not ready to acknowledge that Manila, or any other Southeast Asian claimant, has legitimate grievances that must be addressed to peacefully manage disputes. This increases the risks of escalation as Beijing seems to believe that other States are less committed to their sovereignty and rights, defy China only because of American interference and will eventually buckle in the face of sustained pressure [...] In China’s long-embedded view of regional hierarchy, smaller States are historically and necessarily subservient to Beijing in the Asian pecking order [...] Beijing’s unwillingness to treat the concerns and grievances of its regional neighbours as legitimate has now become one of the most prominent challenges to its management of external relations”.

They go on to add that “the Biden administration’s progress in strengthening relations with countries across the region, from Australia to India to the Philippines, is less a story of diplomatic acumen and more one of Chinese truculence”. All in all, the US’ history of relative regional hegemony does not help to explain the contemporary alignment behavior by regional countries, which are incentivized to cooperate with the United States on security matters precisely because Chinese assertiveness is increasing. China’s continued use of gray zone tactics and the hostility underpinning these tactics thus ramp up regional tensions while motivating a continued regional support for a security presence of the United States. 



This submission has examined China’s use of gray zone tactics and national and regional responses thereto through two empirical cases: Japan and the Philippines. The fact that China deploys gray zone tactics in both instances is telling given that the geographical and historical context of the disputes in the East China Sea and the South China Sea is a markedly different one. Moreover, Chinese gray zone tactics are not solely maritime in nature and can also include disinformation campaigns, State-led informal sanctions, and ‘lawfare’ operations that seek to legitimize Chinese actions through extant or new supposedly international legislation. Whilst the exact scope of the tactics will differ between cases, a generally coercive nature is inherent in how China projects power without crossing the line to more escalatory forms of confrontation. Studying, understanding, and responding to Chinese gray zone tactics will also be crucial in other regional theaters, including in South Asia and the wider Indian Ocean region, as China’s strategic and economic presence in these areas grows. 

Although gray zone tactics allow China to project power, the long-term effects may rather be detrimental as these tactics incentivize the target State to ramp up its capacities, including through potentially deepening the cooperation with other regional powers. This is what happened in the cases of Japan and the Philippines, both of which have invested into their indigenous capabilities while further seeking to balance China externally through deepening security cooperation with the US and expanding the number of regional countries they share close defense ties with.

That said, Chinese behavior currently appears to become more, not less, aggressive. As a result, regional tensions in the Indo-Pacific will likely keep on rising. 


March 2024. © European Foundation for South Asian Studies (EFSAS), Amsterdam