Introduction

The Indo-Pacific is emerging as a consequential geopolitical region due to the prospects of dynamic economic growth, on the one hand, and the rise of an expansionist China, on the other. Among the multiple flashpoints in the region, the South China Sea remains the most critical, given heightened risks of miscalculation or unintended escalation due to errors in judgment, misunderstandings, or misinterpretations of actions among the involved parties; the degree of power asymmetry; and concerns over future uncertainty. Within this protracted dispute, the Philippines has been facing more acute security risks in the West Philippine Sea—what Manila calls the part of the South China Sea that encompasses its 200 nautical mile exclusive economic zone (EEZ).

While China’s expansionist ambitions in the West Philippine Sea was already evident in the second half of the 20^th century with the occupation of Mischief Reef in 1995, the growth in China’s material power and its willingness to leverage this for its great-power ambitions have led to more escalatory activities in Philippine waters. Under the current administration of President Ferdinand Marcos Jr., Manila has reoriented its foreign and security policy to have the security of the West Philippine Sea at the core. This has led to a recalibration of national security, as seen in the implementation of the Comprehensive Archipelagic Defence Concept (CADC). The CADC aligns the Philippines’ military modernisation programme and operations based on securing the nation’s archipelagic waters, territorial sea, and EEZ.^[1]

However, the Philippines has limited material resources and assets to keep the West Philippine Sea free, open, and rules-based. As Manila seeks to play a larger role as a stakeholder in the Indo-Pacific’s rules-based order, it has become a hub for likeminded cooperation against revisionist forces. In this context, since the establishment of their strategic partnership in 2015, Manila and Tokyo have expanded the scope of their maritime security partnership based on their shared interests and objectives for the region.^[2]

Japan’s increasing strategic and maritime engagement with the Philippines has led to key developments and strategic initiatives in recent years. The two countries have been building stronger ties for over two decades, with the partnership seeing progress in the last eight years, propelled by converging threat perceptions in an increasingly volatile Indo-Pacific. The finalisation of the Reciprocal Access Agreement (RAA) on 8 July 2024^[3] comes at an opportune time. The RAA, Japan’s first such agreement in Asia, will facilitate the entry of equipment and troops for combat training and disaster response, enhancing military cooperation between Manila and Tokyo.^[4]

In 2023, Manila witnessed a number of maritime incidents of increasing frequency and incited by Beijing. For Japan, the Philippines has always been a natural partner in the ASEAN region in a relationship that has been strengthened with the signing of the RAA. Both countries, being archipelagic, share interests in maritime security and ensuring freedom of navigation along vital Sea Lines of Communication. Their collaboration also responds to China’s increasing maritime presence in the East and South China seas.^[5] The Philippines faces almost regular intimidation by China in the South China Sea, while Japan deals with pressure around the Senkaku Islands. Both nations view China’s expansionist policies as a serious threat to regional stability and territorial integrity. This shared perception has been the foundation of strategic maritime diplomacy between Japan and the Philippines, aimed at countering China’s influence and maintaining status quo in the region.

The Evolution of Japan’s Defence Engagement

The evolution in the nature and scope of Japan’s strategic engagement has been gradual, being fraught with limitations on the extent of the country’s defence partnerships.

First, Japan’s post-Second World War pacifist Constitution, particularly Article 9,^[a] restricts its military capabilities and the scope of its defence engagements. This constitutional pacifism creates a legitimacy issue for the Self-Defence Forces (SDF), limiting Japan’s ability to engage in defence partnerships fully. For example, Japan faced hurdles in providing defence support to the Philippines due to its restrictive 1967 “three principles” policy, which banned arms exports. Progress began in 2011, with expanded coast guard and naval exercises and a strategic partnership pact in 2012.^[6] Legal easing allowed for more extensive cooperation, including joint exercises and port visits by Japanese warships. By the mid-2010s, Japanese military aircraft could refuel in the Philippines, and bilateral air force exercises began in 2021.^[7] The Japanese Ministry of Foreign Affairs reported that these exercises are designed to bolster the defence capabilities of both nations, ensuring that they can effectively manage potential conflicts and maintain regional security.^[8]

Former Prime Minister Shinzo Abe further relaxed these rules in 2014, enabling easier transfers of defence equipment alongside more extensive cooperation.^[9] This included joint exercises and port visits by Japanese warships to the Philippines, which enhanced the operational capabilities and interoperability of both countries’ maritime forces.^[10] According to the Japan Ministry of Defence, these initiatives were part of a broader strategy to promote regional stability and counterbalance China’s assertive actions in the South China Sea.^[11] For instance, by leveraging the Japan International Cooperation Agency’s Official Development Assistance program, Japan was able to fund the construction of patrol boats for the Philippine Coast Guard.^[12] Additionally, Japan modified national security laws to transfer excess military equipment, including the TC-90 trainer aircraft to Manila.

Regular high-level dialogues between the countries have increased since 2012, highlighting Japan’s growing security engagement with the Philippines.^[13] These dialogues, involving senior civilian defence officials and uniformed officers, have evolved into a ‘2+2 ministerial framework’, with defence and foreign ministers meeting concurrently to discuss strategic issues. Annual meetings of national security advisors from Japan, the Philippines, and the United States (US) underscore the trilateral dimension of this partnership.^[14] The Japanese government has emphasised that these dialogues are essential for coordinating defence policies and ensuring a unified response to regional security challenges.

In December 2022, Japan unveiled its new National Security Strategy, which included a doubling of its defence budget to make it the third largest in the world after the US and China. This increase is aimed at addressing the rapid military buildup of China and enhancing Japan’s counteroffensive capabilities, including the acquisition of intermediate-range missiles.^[15]

In April 2023, Japan established the Overseas Security Assistance programme, potentially facilitating more defence transfers, such as P-3 maritime patrol aircraft. The Overseas Security Assistance programme represents Japan’s latest and most significant effort to enhance defence support. As part of this plan, Japan initiated its first-ever foreign military assistance grant to Manila, amounting to two billion yen (approx. US$15 million),^[16] to enhance the security of its sea lanes in the South China Sea. Although modest, this aid highlights Japan’s increasing security engagement with the Philippines as a key part of its long-term strategy to strengthen ties with Southeast Asia.^[17] The programme also facilitates further strengthening of the Philippines’ maritime security against Chinese assertiveness.^[18] Tokyo also deployed its largest coast guard patrol ship, the Akitsushima, in June 2023, to aid trilateral exercises with Philippine and American forces.^[19]

Second, Japan’s defence budget constraints and the need for modernisation of its military capabilities pose challenges in fully committing to and supporting extensive defence partnerships. Historically, Japan’s defence budget has been limited to around 1 percent of its Gross Domestic Product (GDP), reflecting its post-Second World War pacifist ethos. Japan’s defence budget constraints are rooted in its economic policies and domestic priorities. The country has historically allocated a large portion of its budget to social welfare programmes to support its ageing population. This demographic challenge diverts financial resources away from defence spending, leaving less room for increases in military budgets.^[20]

This budgetary limitation has also impacted Japan’s ability to modernise its Self-Defence Forces (SDF) and expand its military capabilities. The need for modernisation of Japan’s military capabilities is driven by regional security threats, particularly from North Korea and China. China’s military expansion—including its nuclear arsenal and missile capabilities, frequent intrusions near the contested Senkaku/Diaoyu islands, and activity in the East China Sea—poses threats to Japan. Tensions over Taiwan, which is critical for Japan’s energy and trade, exacerbate these concerns. North Korea’s missile developments, which are targeting even US bases in Okinawa, pose further threats. Additionally, Russia’s invasion of Ukraine and increased military activities around Japan, including missile deployments on the disputed Kuril Islands,^[21] heighten regional instability. Joint military exercises by China and Russia amplify these security challenges.^[22]

Former Prime Minister Fumio Kishida’s 2022 National Security Strategy doubled the defence budget to 2 percent of GDP, aligning with NATO standards and aimed at acquiring new counterstrike capabilities. This policy augmentation is aimed at enhancing Japan’s defence posture^[23] to deter regional threats and support extensive defence partnerships, particularly with the US.

Third, there is domestic political opposition in Japan towards expanding military roles and deepening defence partnerships, rooted in pacifist public sentiment and political dynamics.^[24] The Japanese public and political landscape have historically been wary of military expansion due to wartime trauma.^[25]

Efforts to reinterpret or amend Article 9 to allow for greater military flexibility have previously faced resistance from various political factions as well as the general populace. For instance, Shinzo Abe’s push to reinterpret the Constitution to enable collective self-defence sparked widespread protests and political debates.^[26] Japan’s defence policy is also influenced by the fear of entanglement in foreign conflicts. The public’s opposition to deploying troops overseas for combat roles, as seen in the limited Japanese military involvement in Iraq and Afghanistan, stems from a cautious approach to avoid becoming embroiled in international conflicts. This cautious stance reflects a broader strategic culture that favours minimal use of military force abroad.

However, China’s aggressive conduct in Asia’s maritime regions has persuaded the Japanese public of the importance of enhancing their country’s security presence overseas.^[27]  In the past several years, there has been increased public support for revising Article 9 of the Japanese Constitution. For instance, the enactment of national security laws in 2015, which allow Japan to engage in collective self-defence and support allies under attack, was the subject of increased public debate.^[28] Despite initial opposition, public acceptance has grown as the regional security environment has deteriorated. While domestic public opinions about Japan’s increased military role vary, advocates argue that it is necessary for regional stability.^[29]

Nevertheless, public opinion is increasingly turning in favour of boosting Japan’s defence budget. The government’s decision to increase the defence budget to 2 percent of GDP, aligning with NATO standards, has gained public support and is being viewed as necessary to counter regional threats and enhance national security.^[30] The public has also shown growing support for enhancing Japan’s defence capabilities through advanced technologies,^[31] including missile defence systems and cyberwarfare capabilities, reflecting a shift towards acknowledging the need for a technologically advanced military to ensure national security. Surveys indicate that most Japanese citizens now view a strong military as essential^[32] to national defence, marking a shift from the post-war pacifist outlook.

From Cooperation to Strategic Partnership: Imperatives for Japan and the Philippines

The Philippines’ foreign and defence policy calculations have fluctuated since its independence in 1946. A shift occurred in 2010, arising from concerns over insurgent and secessionist groups in the southern islands of Mindanao, when the country’s security perception gravitated towards territorial defence from a largely internal defence orientation.^[33] This shift was reflected in Manila’s external relations and threat perceptions.

One of the catalysts for this change was China’s unilateral attempts to pursue its expansionist ambitions within the Philippines’ lawful exclusive economic zone (EEZ) in the South China Sea. Since submitting its nine-dash line map to the United Nations in 2009, China has not only maintained double-digit defence growth but also increased the presence and operations of the Chinese Coast Guard (CCG) and maritime militia to assert illegitimate claims in the South China Sea at the expense of the sovereignty and sovereign rights of claimant countries, including the Philippines.^[34] As China’s material power grew, its expansionist behaviour became more pronounced and aggressive, particularly in the West Philippine Sea, or the part of the South China Sea that encompasses the Philippine EEZ.^[35]

Various Philippine administrations have formulated methods to address this issue. While attempts at military and coast guard modernisation are vital to the country’s defences, its limited resources and the lack of a coordinated long-term military strategy have proven to be inadequate to deter Chinese belligerence.

In such circumstances, the most pragmatic step for any middle power is to forge robust security ties with more capable partners that can supplement its interests. For the Philippines, one would assume that relying on the US would be Manila’s most logical step to address the China challenge. Washington, after all, is the sole treaty ally of the Philippines and its most significant security provider since its independence. However, the degree to which Washington has been involved in Manila’s security calculations has fluctuated throughout various administrations in the 21^st century for various reasons. For instance, under former President Benigno Aquino III (2010-2016), Manila relied solely on US alliance to balance against China’s aggression in the West Philippine Sea.^[36] However, under the Rodrigo Duterte administration (2016-2022), Manila sought to distance itself from Washington and downplay the challenges posed by China in Philippine waters with the hopes of gaining economic concessions from Beijing.^[37]

Despite the decreased momentum of Philippines-US security ties, the Duterte administration pursued strategic partner diversification. Under the current presidency of Marcos Jr., Manila is pushing for a more robust partnership with the US, after realising the unreliability of China’s pledges and its unwillingness to manage its expansionist ambitions.^[38] Therefore, while the US remains the most materially capable partner of the Philippines, especially by virtue of their alliance, its role in Manila’s strategic calculations has been the subject of controversies and vacillations.

Meanwhile, Manila’s security partnership with Tokyo has been a consistent and increasingly crucial element in the former’s foreign policy since its shift to territorial defence and maritime security. The Philippines has been consistently receptive to Japan’s role in regional peace and development. Japan has been the Philippines’ largest bilateral source of official development assistance (ODA) for over 20 years and a major investor and trade partner of the Southeast Asian nation.^[39]  Manila has also looked to Japan as crucial for the capacity building of its security, particularly in the maritime domain.^[40]

Sustained economic engagement has allowed Japan to remain a trusted partner under various administrations in the Philippines, from the reformist policies of Aquino III to the populist governance of Duterte and now the moderate approach of Marcos Jr. During the Aquino administration, Japan played a pivotal role in supporting the Philippines’ public-private partnership infrastructure programme, which emphasised transparency and efficiency.^[41] This included significant contributions to projects like constructing roads, railways, and airports, demonstrating Japan’s commitment to Aquino’s reform-driven development agenda.

Aquino III and Abe also deepened security cooperation, laying the groundwork for Japan’s strategic engagement in the region. Under Duterte, Japan maintained its strategic position by aligning its assistance with Duterte’s “Build, Build, Build” initiative, despite the Philippine president’s pivot to China and the controversies surrounding his administration.^[42] Japan funded key infrastructure projects such as the Metro Manila Subway and the North-South Commuter Railway, addressing critical urban transportation challenges.^[43] These investments reflect Tokyo’s ability to work with leaders across the political spectrum while emphasising shared regional connectivity and development goals.^[44]

Japan’s engagement with Southeast Asian nations, particularly the Philippines, emphasises the former’s commitment to maritime security. Since the 1950s, Japan has provided war reparations to the Philippines as part of the San Francisco Peace Treaty. These reparations were used for infrastructure projects and development programmes, which helped in the post-war reconstruction of the Philippines and established an early economic linkage between the two nations.^[45] By the 2000s, Japanese leaders viewed stronger ties with the Philippines, alongside US alliances, as enhancing Western Pacific deterrence—a view that is supported by Washington.^[46] This relationship was boosted in 2011, under Yoshihiko Noda’s leadership, when the Japan-Philippines strategic partnership was established. Bilateral ties experienced a rapid increase during Abe’s second term.^[47] Since then, maritime security cooperation has become Japan’s cornerstone.^[48]

Japan’s maritime diplomacy with the Philippines is a crucial component of its broader strategic purview of “Proactive Contribution to Peace”.^[49] Initiated under Abe’s second term, the policy marked a shift in Japan’s post-Second World War pacifist stance, allowing for a more active role in regional and global security. The policy also emphasises collective self-defence and has enabled Japan to enhance its security ties with key partners, including the Philippines.

Japan’s cooperative security measures with the Philippines include joint naval exercises, capacity-building programmes, and strategic dialogues aimed at improving the maritime capabilities of the Philippine Coast Guard and Navy. Such initiatives are integral to Japan’s broader national security strategy.^[50] The emphasis on balance of power is evident in Japan’s efforts to provide the Philippines with patrol vessels, surveillance equipment, and training programmes designed to enhance maritime domain awareness and operational readiness. Both countries are long-standing US treaty allies, which has further facilitated strategic cooperation. This cooperation is crucial for fostering a collective response to potential threats and maintaining the rule of law in international waters.^[51]

Tokyo’s recognition of the challenges posed by an expansionist China in the Western Pacific catalysed Japan’s increased engagement in regional security. Japan also sought to deepen its security engagements with like-minded partners such as the Philippines, which shared similar concerns in the maritime domain. Consequently, the Abe government reinterpreted Japan’s Constitution to reflect Tokyo’s willingness to play a more active role as capacity builder. One of the most important developments came in 2014, when Tokyo adopted the revised “Three Principles of Transfer of Defence Equipment and Technology”, which was based on the December 2013 National Security Strategy (NSS)^[52] and replaced the previous “Three Principles on Arms Exports and Their Related Policy Guidelines”. This made it easier for Japan to provide defence and security equipment to friendly countries.

Among friendly partners, the Philippines largely benefited from Tokyo’s policy shift. Tokyo believed that enhancing the Philippines’ capacity in maritime security does not pose any conflicts of interest, given the latter’s support of international law-based engagements. Both countries being US treaty allies that share democratic principles and threat perceptions added significance to their partnership. Manila signing a Defence Equipment and Technology Transfer Agreement with Tokyo in 2016 enabled further defence transfers. Moreover, Abe’s incorporation of maritime safety into Japan’s ODA allowed the country to fund the construction of 10 unarmed Parola class patrol boats for the Philippine Coast Guard (PCG).^[53],[54] The vessels were delivered during the 2016-2018 timeframe. The Philippines also received five Japanese-donated TC-90 aircraft during the same period.^[55]

Additionally, Japan’s maritime strategy is part of its broader vision for a Free and Open Indo-Pacific (FOIP), emphasising the importance of maritime security, freedom of navigation, and adherence to international laws. Japan has been actively promoting this concept through multilateral forums and bilateral partnerships, aiming to create a regional security architecture that can deter unilateral actions.^[56] This stance is reflected in Japan’s support for the Philippines’ legal victory in the 2016 Permanent Court of Arbitration ruling,^[57] which invalidated China’s historical claims in the South China Sea.

The FOIP’s strengths lie in its flexibility and continuity. Tokyo has even integrated provisions within its domestic institutional mechanisms to support necessary changes and meet the requirements of its FOIP vision. Japanese diplomacy has evolved from a sole reliance on its bilateral relationship with the US to building robust security and strategic partnerships with Indo-Pacific countries that share concerns about China. Additionally, Japan’s strategic direction through the successive administrations of Shinzo Abe (2012-2020), Yoshihide Suga (2020-2021), and Fumio Kishida (2021-present) has consistently promoted the realisation of the FOIP vision.^[58]

The FOIP also draws on Japan’s ability to emphasise its “Asian identity” and distinct “non-Western” cultural narrative, which has been a critical asset in diplomatic engagements across the Indo-Pacific, particularly when navigating relationships with leaders such as Rodrigo Duterte.^[59] Unlike Western powers, whose diplomacy in Asia is often perceived through a lens of postcolonial influence or even, at times, external interference, Japan’s position as an Asian nation with shared regional experiences offers it a unique platform for engagement.

Tokyo can therefore leverage its Asian identity to frame its developmental aid, infrastructure projects, and security cooperation as a shared endeavour for regional stability and prosperity rather than as an imposition of external values. For instance, Japan’s aid to the Philippines under Duterte was presented as part of a broader goal of regional resilience, eschewing overt political conditionalities.^[60]

Furthermore, Japan’s cultural diplomacy highlights its heritage, traditional values, and modernity without being overtly assertive. This soft power projection helps to foster goodwill and trust, creating a foundation for deeper bilateral cooperation. Japan’s dual identity as a global power and a deeply Asian nation positions it as a credible and more approachable partner.^[61]

As Tokyo reinterpreted and modified its national security regulations to enhance defence cooperation, the transfer of defence equipment was not the only notable development between Manila and Tokyo. In 2015, Japan and the Philippines held their coast guard and naval drills to demonstrate joint preparedness against “unplanned encounters at sea”.^[62] The first 2+2 format between Philippine foreign affairs and defence secretaries and their Japanese counterparts in 2022 reflected a practical evolution of their bilateral partnership.

Tokyo has also become more vocal about the potential security implications of a cross-Strait crisis in the event of China’s invasion of Taiwan.^[63] This development has coincided with the Marcos Jr administration’s acknowledgement of the direct security implications of any geopolitical crisis in Taiwan, given the role of geography, the treaty obligations under the Mutual Defence Treaty, and the presence of over 200,000 Filipino overseas workers in the island nation.^[64],[65] The Taiwan issue has significant implications for the Japan-Philippines security partnership, and both countries recognise Taiwan’s strategic importance in the broader context of regional security.^[66] Taiwan lies near vital shipping routes for Japan, and a conflict over the island could threaten these routes and Japan’s economic security. Similarly, the Philippines, given its geographical proximity to Taiwan, could face both direct and indirect consequences from any regional escalation. It is in this context that the integration of the traditional hub-and-spoke framework becomes crucial.

The inaugural summit of the Philippines-Japan-US trilateral summit in Washington in April 2024 highlighted a long-term roadmap for more consistent trilateral maritime security activities between the three partners—not only in the West Philippine Sea but also across the Taiwan Strait. Recognising the perils of geography, Manila and Tokyo have expanded their attention to include the defence of their islands that lie close to Taiwan.^[67] The US plays a vital role in operationalising these activities. For instance, in the 2024 Balikatan exercise between the Philippine and US militaries, held in the northern region of the Philippines facing Taiwan, simulations of island takeovers and ship sinking were conducted.^[68] Similarly, the 2023 iteration of the Iron Fist exercise between the US and Japan was the first such held in the East Asian state.^[69]

For a more comprehensive layer of deterrence, the Philippines houses the US mid-range Typhon missile system in its north, while Washington is in talks with Tokyo regarding the possible deployment of the former’s High Mobility Artillery Rocket Systems to Japan’s Nansei Islands, located 850 kilometres from Taiwan.^[70]

While such developments are vital for regional maritime security, the depth of involvement of Japanese and Philippine forces during a potential Chinese invasion of Taiwan remains uncertain. This is because it is unlikely that Japan would deploy ground forces in the South China Sea, even if tensions escalate. Japan’s constitutional restrictions and its post-Second World War security policy limit military engagement overseas unless Japan itself faces a direct threat. In scenarios involving the South China Sea, Japan would more feasibly resort to diplomatic pressure, economic sanctions, or logistical support for the Philippines through intelligence sharing and indirect assistance under the framework of regional security partnerships like the Quad and bilateral agreements.

Japan’s willingness to go beyond these measures would hinge on multilateral consensus, particularly from the US and ASEAN, to ensure that any action aligns with its broader security interests and legal commitments. Nevertheless, Japan’s strong stance on freedom of navigation and its proximity to Taiwan suggests that it might become more involved if escalation threatens regional stability and Japanese interests, but such involvement would likely be through multilateral frameworks rather than unilateral military deployment.

Under the Kishida government, Japan pursued a more robust security-driven foreign policy due to the exacerbating security conditions of the Indo-Pacific brought about by China’s expansionism and concerns over the long-term security commitment of the US in the region.^[71] Tokyo felt that it was necessary strengthen its role not just as a development provider but also as a regional security provider. This emboldened position was evident in Tokyo’s December 2022 NSS, which aimed not only at bolstering Japan’s military capabilities but also at enhancing the security capacity of likeminded regional partners.^[72],[73] Tokyo recognised the need to form a network of likeminded partners to push back against Chinese revisionism in the region, particularly in the maritime domain. This was operationalised through the Official Security Assistance (OSA), through which Japan provides defence equipment and assistance to the militaries of its partners.^[74]

The Philippines was the first beneficiary of the OSA, which came in the form of a coastal surveillance radar system to improve the capabilities of the PCG.^[75] Additionally, Marcos Jr approved the acquisition of five 97-metre cutters from Japan for the PCG.^[76] These developments are in line with the Philippines’ Re-Horizon 3 military modernisation programme, which is anchored on the CADC’s focus on fast-tracking the country’s acquisition of naval, coast guard, and aerial assets and technology to better secure its EEZ and supplement the objective of  maintaining constant physical presence in Philippine waters. Accordingly, any security collaboration between Manila and Tokyo will likely centre on coastal defence.

Moreover, in addition to the signing of the RAA, Japan has been an anchor for the Philippines to explore security-driven arrangements in the Indo-Pacific. The implementation of the logistics pact will allow for a more efficient process for operationalising collaborative activities between Filipino and Japanese forces. However, there are limitations to this agreement. While it may seem similar to the Visiting Forces Agreement between Manila and Washington, the RAA is unlikely to possess the level of sophistication as the Philippines and the US, especially because, unlike the US, Japan is not a treaty ally of the Philippines. This means that Tokyo is unlikely to deploy weapon systems in the Philippines or have the same control that US troops have over the Enhanced Defense Cooperation Agreement (EDCA) sites. Nevertheless, creating avenues for more immediate joint deployments is crucial in times of conflict or crisis.

The Philippines-Japan security partnership has gained traction in Indo-Pacific geopolitics. More importantly, the deepening bilateral relationship has provided Manila with a formidable diplomatic anchor that would allow for deeper integration within the existing US-led alliance network. For instance, the Philippines-Japan-US trilateral has expanded to include Australia in a four-way arrangement. This integration among eastern partners has also provided opportunities for Washington’s western allies, such as France and Canada, to forge strategic linkages.^[77] With the Philippines becoming a pivotal fulcrum within eastern and western alliance networks, the next practical step will be to institutionalise cooperation to ensure policy continuity in the Philippines regarding its role and utilisation of the increasingly integrated alliance dynamics towards the security of the established regional order amid concerns over China’s unilateralism and expansionism. It is against this backdrop that a stronger Philippines-Japan partnership becomes more vital for the future of Indo-Pacific security.

Conclusion

The maritime security partnership between the Philippines and Japan has strengthened over time, not only because of shared structural concerns but also because of a convergence of interests in the region. Today, the strategic partnership between Manila and Tokyo has become strong enough to stand on its own and flexible enough to be integrated within broader multilateral security arrangements with likeminded states that seek to secure the established regional rules-based order. However, while the bilateral momentum continues to grow, it is imperative for the Philippines and Japan to navigate the future uncertainty of Indo-Pacific geopolitics, given the changes in leadership in Japan and the US, the continuous escalation of Chinese activities at sea, and concerns over foreign policy continuity in Manila. By institutionalising cooperation, the Philippines and Japan are likely to secure the trajectory of their bilateral security partnership in the long term.

Regime change in either Japan or the Philippines could affect the partnership, which has increasingly focused on mutual security concerns in the Indo-Pacific. Fumio Kishida’s resignation and the Liberal Democratic Party’s (LDP) poor performance in the October 2024 elections marked a period of uncertainty in Japan. Kishida has been instrumental in strengthening Japan’s foreign policy and defence posture, with substantial attention on the Philippines as a key partner in counterbalancing China’s regional ambitions. Should a new leader adopt a less assertive defence stance, Japan’s commitment to the Philippines could be tempered, potentially altering the momentum of current defence agreements like the RAA and broader joint initiatives in the South China Sea. However, as the LDP remains broadly supportive of defence alliances in Southeast Asia, there may be some continuity in the bilateral relationship, depending on the next administration’s approach to regional security concerns.

In the Philippines, while President Marcos Jr has prioritised a strong defence partnership with Japan, future elections could introduce new priorities depending on leadership changes. If a successor prioritises a more independent stance or shifts focus to economic over security cooperation, the Philippines might reconsider its alliance with Japan. However, the enduring relevance of shared regional threats, such as China’s maritime assertiveness, will likely ensure that security cooperation remains focused on the bilateral agenda, although its intensity and focus could vary based on leadership styles and regional pressures.

The recent Japan-Philippines RAA enhances Tokyo’s regional security influence, enabling both countries to better prepare for and respond to threats. While providing the Philippines with new patrol vessels and allowing Japan access to Philippine bases is unlikely to drastically alter the naval power balance in the South China Sea, it will enhance the Philippines’ maritime domain awareness and help Japan monitor China’s maritime activities and naval expansion.^[78] This pact promotes increased intelligence sharing, joint military exercises, and technology transfers between the two nations. It also facilitates coordinated defence strategies and force deployments in strategic areas like Batanes in the northern Philippines and Okinawa in southern Japan, near Taiwan. This ‘spoke to spoke’ cooperation signifies a mutual effort to boost defence capabilities and strategic independence.^[79]

In this context, Japan has been essential to the Philippines’ security and foreign policy calculations. As Tokyo continues to embrace a more proactive interpretation of its regional security responsibilities, the Philippines remains increasingly supportive of a more robust bilateral partnership with Japan. Therefore, given the growing uncertainties in Indo-Pacific geopolitics, it is likely that Manila-Tokyo ties will strengthen, diversify, and evolve based on the changing security architecture of the region.

Endnotes

^[a] Article 9 of Japan's Constitution, adopted in 1947, renounces war as a sovereign right and prohibits maintaining military forces for combat purposes. Japan established the Self-Defense Forces (SDF) in 1954, as a strictly defensive measure. Over time, reinterpretations, particularly in 2014, allowed limited collective self-defence, enabling Japan to support allies under threat. Article 9 has not been formally amended, but debates persist about revising it to address modern security challenges, such as North Korea’s missile tests and China’s assertiveness. Proponents seek clarity on the SDF's role, while opponents fear undermining Japan’s pacifist identity and escalating regional tensions.

^[1] Priam Nepomuceno, “CADC to Allow PH to Defend Sea Lanes of Communication,” Philippine News Agency, March 20, 2024, https://www.pna.gov.ph/articles/1221211.

^[2] Government of Japan, Ministry of Foreign Affairs, “Japan-India Joint Statement Toward Advancing Strategic Partnership,” Ministry of Foreign Affairs of Japan, 2015, https://www.mofa.go.jp/s_sa/sea2/ph/page4e_000280.html.

^[3] Ministry of Foreign Affairs of Japan, “The Japan-Philippines RAA,” 2024, https://www.mofa.go.jp/s_sa/sea2/ph/pageite_000001_00432.html#:~:text=The%20Japan%2DPhilippines%20RAA%20is,status%20of%20the%20visiting%20force.

^[4] Mikhail Flores and Karen Lema, “Philippines Says Pact with Japan Takes Defence Ties to Unprecedented High,” Reuters, July 8, 2024, https://www.reuters.com/world/asia-pacific/philippines-japan-sign-landmark-defence-deal-2024-07-08/.

^[5] Julius Cesar Imperial Trajano, “Japan-Philippines Strategic Partnership: Converging Threat Perceptions,” RSIS Commentary, 2013, https://www.rsis.edu.sg/rsis-publication/rsis/2034-japan-philippines-strategic-pa/?doing_wp_cron=1722840157.1688969135284423828125.

^[6] Renato Cruz De Castro, “Philippines and Japan Strengthen a Twenty-First Century Security Partnership,” Asia Maritime Transparency Initiative, Center for Strategic and International Studies, 2015, https://amti.csis.org/philippines-and-japan-strengthen-a-twenty-first-century-security-partnership/.

^[7] Felix K. Chang, “Japan’s Security Engagement with the Philippines,” Foreign Policy Research Institute, 2023, https://www.fpri.org/article/2023/08/japans-security-engagement-with-the-philippines/.

^[8] Embassy of Japan in the Philippines, “First Air-to-Air Bilateral Training on Humanitarian Assistance and Disaster Relief between Japan Air Self-Defense Force and the Philippine Air Force,” Embassy of Japan in the Philippines, 2021, https://www.ph.emb-japan.go.jp/itpr_en/11_000001_00467.html.

^[9]Government of Japan, Ministry of Foreign Affairs, “The Three Principles on Transfer of Defense Equipment and Technology,” Ministry of Foreign Affairs of Japan, 2023, https://www.mofa.go.jp/fp/nsp/page1we_000083.html.

^[10] Mynardo Macaraig, “Philippines and Japan Hold Historic Naval Drills in Flashpoint Waters,” SpaceDaily, 2015, https://www.spacedaily.com/reports/Philippines_and_Japan_hold_historic_naval_drills_in_flashpoint_waters_999.html.

^[11] Ministry of Defense, Japan, “Defense Equipment and Technology Cooperation Policy,” Acquisition, Technology & Logistics Agency, Ministry of Defense, Japan, 2014, https://www.mod.go.jp/atla/en/policy/defense_equipment.html.

^[12] Japan International Cooperation Agency, “JICA and the Philippines: Strengthening Maritime Safety and Security Cooperation,” JICA Philippines Office, 2020, https://www.jica.go.jp/Resource/philippine/english/office/topics/news/200213.html.

^[13] Felix K. Chang, “Japan’s Security Engagement with the Philippines,” Foreign Policy Research Institute, 2023, https://www.fpri.org/article/2023/08/japans-security-engagement-with-the-philippines/.

^[14]The White House, “Joint Readout of Trilateral Meeting Between the National Security Advisors of the United States, Japan, and the Philippines,” The White House, 2023, https://www.whitehouse.gov/briefing-room/statements-releases/2023/06/16/joint-readout-of-trilateral-meeting-between-the-national-security-advisors-of-the-united-states-japan-and-the-philippines/.

^[15] Kanehara Nobukatsu, “Reading Japan’s National Security Strategy,” Taylor and Francis Online, 2023, https://www.tandfonline.com/doi/full/10.1080/13439006.2023.2198854.

^[16] Japan Coast Guard, “Japan Coast Guard Activities: A Summary,” Japan Coast Guard, https://www.kaiho.mlit.go.jp/e/topics_archive/article4200.html.

^[17] Chang, "Japan's security engagement with the Philippines."

^[18] Nobukatsu, "Reading Japan’s National Security Strategy."

^[19] Hiroshi Asahina, “Japan Eyes Philippines as First Recipient of Security Grant,” Nikkei Asia, 2023, https://asia.nikkei.com/Politics/International-relations/Japan-eyes-Philippines-as-first-recipient-of-security-grant.

^[20] Marina Fujita Dickson and Yoichi Funabashi, “The Next Generation of Japan’s National Security,” Asia Policy 18, no. 2 (2023), https://muse.jhu.edu/article/893911.

^[21] Reuters, “Russia Deploys Defense Missile System on Kuril Island Near Japan,” Reuters, 2022, https://www.reuters.com/business/aerospace-defense/russia-deploys-defence-missile-system-kuril-island-near-japan-2022-12-06/.

^[22] Jingdong Yuan, “Japan’s New Military Policies: Origins and Implications,” Stockholm International Peace Research Institute, February 2, 2023, https://www.sipri.org/commentary/blog/2023/japans-new-military-policies-origins-and-implications.

^[23] Nobukatsu, "Reading Japan’s National Security Strategy."

^[24] Rintaro Nishimura, “Opposition Party Could Hold Deciding Vote on Japan’s National Security Policy,” The Interpreter, Lowy Institute, 2024, https://www.lowyinstitute.org/the-interpreter/opposition-party-could-hold-deciding-vote-japan-s-national-security-policy.

^[25] Christopher Hughes, “Chapter Six: The Erosion of Japan’s Anti-Militaristic Principles,” The Adelphi Papers 48, no. 403 (2008; Taylor and Francis Online, 2010): 99–138, https://www.tandfonline.com/doi/full/10.1080/05679320902955278.

^[26] Garren Mulloy, “Defenders of Japan Present and Future,” in Defenders of Japan: The Post-Imperial Armed Forces 1946–2016, A History, by Garren Mulloy (Oxford Academic, 2021), https://academic.oup.com/book/38870/chapter-abstract/338002592?redirectedFrom=fulltext.

^[27] Chang, "Japan's security engagement with the Philippines."

^[28] Daisuke Akimoto, “The Abe Government and the Right to Collective Self-Defence,” in The Abe Doctrine, by Daisuke Akimoto (Springer Link, 2018), 65–69, https://link.springer.com/chapter/10.1007/978-981-10-7659-6_4.

^[29] Adam P. Liff and Ko Maeda, “Why Shinzo Abe Faces an Uphill Battle to Revise Japan’s Constitution,” Brookings Institution, 2018, https://www.brookings.edu/articles/why-shinzo-abe-faces-an-uphill-battle-to-revise-japans-constitution/.

^[30] Dickson and Funabashi, “The Next Generation of Japan’s National Security”

^[31] Peter Y. Lindgren and Wrenn Yennie Lindgren, “The Relationship Between Narratives and Security Practices: Pushing the Boundaries of Military Instruments in Japan,” Asian Perspective 43, no. 2 (Johns Hopkins University Press, 2019): 323–348, https://su.diva-portal.org/smash/get/diva2:1592052/FULLTEXT01.

^[32] Itsunori Onodera, “Japan’s New National Security Policy and Defence Strategy in a New Era,” Asia-Pacific Online 26, no. 2 (Taylor and Francis Online, 2019): 37–49, https://www.tandfonline.com/doi/full/10.1080/13439006.2019.1688928.

^[33] Renato De Castro, “The Aquino Administration's Balancing Policy against an Emergent China: Its Domestic and External Dimensions,” Pacific Affairs 87, no. 1 (2014): 5–6.

^[34] Don McLain Gill, “A Neoclassical Realist Analysis of the Evolving Philippines–India Defence Partnership in the Twenty-First Century,” Asian Security 19, no. 3 (2023): 250–256.

^[35] Council on Foreign Relations, “China’s Maritime Disputes,” Council on Foreign Relations, https://www.cfr.org/timeline/chinas-maritime-disputes.

^[36] Renato Cruz De Castro, “Developing a Credible Defence Posture for the Philippines: From the Aquino to the Duterte Administrations,” Asian Politics and Policy 9, no. 4 (2017): 541–563.

^[37] Malcolm Cook, “Applying the Duterte Filter to US-Philippine Relations,” The Interpreter, Lowy Institute, 2016, https://www.lowyinstitute.org/the-interpreter/applying-duterte-filter-us-philippine-relations.

^[38] Joshua Kurlantzick, “Marcos Jr. Moves the Philippines Dramatically Closer to the United States,” Council on Foreign Relations, 2024, https://www.cfr.org/article/marcos-jr-moves-philippines-dramatically-closer-united-states.

^[39] Dennis D. Trinidad, “Japan’s Official Development Assistance (ODA) to the Philippines,” De La Salle University, Manila, 2021: 1–24.

^[40] Don McLain Gill, “Why Japan’s Role in Philippines’ Defence Is Nearly as Big as the US,” South China Morning Post, 2024, https://www.scmp.com/opinion/asia-opinion/article/3270828/why-japans-role-philippines-defence-nearly-big-us.

^[41] Public-Private Partnership Center of the Philippines, “PPP Center Pushes Enhanced Cooperation with Japan,” Public-Private Partnership Center of the Philippines, 2023, https://ppp.gov.ph/in_the_news/ppp-center-pushes-enhanced-cooperation-with-japan/.

^[42]Asian Development Bank, “Philippine PPP Policy Gets Boost with ADB’s $300 Million Loan,” Asian Development Bank, 2018, https://www.adb.org/news/philippine-ppp-policy-gets-boost-adbs-300-million-loan#:~:text=%E2%80%9CThe%20Philippines%20has%20made%20significant,members%E2%80%9448%20from%20the%20region.

^[43] Chihiro Ishikawa, “Japan's KDDI to Take Part in Philippines' First Subway Project,” Nikkei Asia, January 15, 2024, https://asia.nikkei.com/Business/Transportation/Japan-s-KDDI-to-take-part-in-Philippines-first-subway-project.

^[44] Karl Ian Cheng Chua, “Philippine-Japan Relations: Friends with Benefits,” Kyoto Review of Southeast Asia, issue 34 (December 2022), https://kyotoreview.org/issue-34/philippine-japan-relations-friends-with-benefits/.

^[45] United Nations, “Treaty of Peace with Japan (Treaty of San Francisco),” United Nations Treaty Series 136, no. 1832 (1952): 45–130, https://treaties.un.org/doc/publication/unts/volume%20136/volume-136-i-1832-english.pdf.

^[46] Chang, "Japan's security engagement with the Philippines."

^[47] Chang, "Japan's security engagement with the Philippines."

^[48] Trajano, “Japan-Philippines Strategic Partnership.”

^[49] “Efforts for Peace and Stability of Japan and the International Community,” in Diplomatic Bluebook, 2021, https://www.mofa.go.jp/policy/other/bluebook/2021/pdf/pdfs/4-2.pdf.

^[50] Chang, "Japan's security engagement with the Philippines."

^[51] Paul Midford, "Japan’s Approach to Maritime Security in the South China Sea." Asian Survey (University of California Press, 2015), https://online.ucpress.edu/as/article-abstract/55/3/525/24805/Japan-s-Approach-to-Maritime-Security-in-the-South?redirectedFrom=fulltext

^[52] Japan Ministry of Foreign Affairs, “The Three Principles on Transfer of Defence Equipment and Technology,” Japan Ministry of Foreign Affairs, April 1, 2014, https://www.mofa.go.jp/fp/nsp/page1we_000083.html.

^[53]Felix Chang, “Japan’s Security Engagement with the Philippines,” Foreign Policy Research Institute (FPRI), August 28, 2023, https://www.fpri.org/article/2023/08/japans-security-engagement-with-the-philippines/#:~:text=By%20broadly%20interpreting%20economic%20development,delivered%20between%202016%20and%202018.

^[54] Renato Cruz De Castro, “The Philippines and Japan Sign New Defense Agreement,” Asia Maritime Transparency Initiative, Center for Strategic and International Studies (CSIS), 2016, https://amti.csis.org/the-philippines-and-japan-sign-new-defense-agreement/.

^[55] Embassy of Japan in the Philippines, “JMSDF TC-90s Transferred to the Philippine Navy,” Embassy of Japan in the Philippines, 2018, https://www.ph.emb-japan.go.jp/itpr_en/00_000509.html#:~:text=1%20On%20March%2026%2C%20three,%2C%20Sangley%20Point%2C%20Cavite%20City.

^[56] Narushige Michishita, “Japan’s Grand Strategy for a Free and Open Indo-Pacific,” in The Oxford Handbook of Japanese Politics (Oxford Academic, 2021), 492–513, https://academic.oup.com/edited-volume/40699/chapter-abstract/348430888?redirectedFrom=fulltext.

^[57] Kamikawa Yoko, Ministry of Foreign Affairs of Japan, “As Reaffirmed with the Philippines: Binding 2016 Award on the South China Sea,” Ministry of Foreign Affairs of Japan, 2024, https://www.mofa.go.jp/press/release/pressite_000001_00430.html#:~:text=As%20reaffirmed%20with%20the%20Philippines,binding%202016%20award%20on%20the.

^[58] Pratnashree Basu, “Order Through Practice: Assessing Tokyo’s Free and Open Indo-Pacific Vision”, ORF Occasional Paper no. 444, August 1, 2024, https://www.orfonline.org/research/order-through-practice-assessing-tokyo-s-free-and-open-indo-pacific-vision

^[59] Don McLain Gill, “The Significance of a More Robust Philippines-Japan Strategic Partnership,” The Diplomat, February 17, 2023, https://thediplomat.com/2023/02/the-significance-of-a-more-robust-philippines-japan-strategic-partnership/.

^[60] Ralph Jennings, “Japan Pledges Economic Aid to the Philippines,” Voice of America, 2017, https://www.voanews.com/a/japan-economic-aid-philippines/4098258.html.

^[61] Wrenn Yennie Lindgren, “WIN-WIN! with ODA-man: legitimising development assistance policy in Japan”, The Pacific Review, Vol. 24, Issue 4, Taylor & Francis, February

2020, https://doi.org/10.1080/09512748.2020.1727552

^[62] Mynardo Macaraig, “Philippines and Japan Hold Historic Naval Drills in Flashpoint Waters,” AFP News, May 12, 2015; Manuel Mogato, Adam Rose, and Ben Blanchard, “Philippines, Japan Coast Guards Hold Anti-Piracy Drills,” Reuters, May 6, 2015.

^[63] Anthony Kuhn, “After Being Silent for Decades, Japan Now Speaks Up About Taiwan — and Angers China,” Asia Times, August 2, 2021, https://www.npr.org/2021/07/26/1020866539/japans-position-on-defending-taiwan-has-taken-a-remarkable-shift.

^[64] Robin Michael Garcia and Thomas J. Shattuck, “Philippines’ New National Security Plan Falls Short in Taiwan Policy,” The Diplomat, 2023, https://thediplomat.com/2023/10/philippines-new-national-security-plan-falls-short-in-taiwan-policy/.

^[65] Richard Heydarian, “Marcos’ Embrace of Taiwan’s Lai Was More Than a Friendly Gesture,” Nikkei Asia, 2024, https://asia.nikkei.com/Opinion/Marcos-embrace-of-Taiwan-s-Lai-was-more-than-a-friendly-gesture.

^[66] Christopher Woody, “Japan and the Philippines Increase Their Focus on Island Defense,” The Diplomat, 2024, https://thediplomat.com/2024/05/japan-and-the-philippines-increase-their-focus-on-island-defense/.

^[67] Woody, “Japan and the Philippines Increase Their Focus on Island Defense.”

^[68] Arron-Matthew Lariosa, “Balikatan 2024 Drills Prioritize South China Sea, Luzon Strait,” USNI, 2024, https://news.usni.org/2024/04/22/balikatan-2024-drills-prioritize-south-china-sea-luzon-strait.

^[69] Indo-Pacific Defense Forum, “Iron Fist Deepens Integration of Japanese, U.S. Forces,” Indo-Pacific Defense Forum, 2024, https://ipdefenseforum.com/2024/03/iron-fist-deepens-integration-of-japanese-u-s-forces/#:~:text=The%20exercise%2C%20which%20concluded%20in,artillery%20and%20close%2Dair%20support.

^[70] Christy Lee, “New Missile Plan by US-Japan Eyes Chinese Invasion of Taiwan,” Voice of America (VOA), November 27, 2024, https://www.voanews.com/a/new-missile-plan-by-us-japan-eyes-chinese-invasion-of-taiwan-/7879818.html.

^[71] Mirna Galic, “How Fumio Kishida Shaped Japan’s Foreign Policy,” United States Institute of Peace, 2024, https://www.usip.org/publications/2024/08/how-fumio-kishida-shaped-japans-foreign-policy.

^[72] “National Security Strategy of Japan,” Cabinet Secretariat (CAS), December 2022, https://www.cas.go.jp/jp/siryou/221216anzenhoshou/nss-e.pdf.

^[73] Government of Japan, “National Security Strategy of Japan,” Cabinet Secretariat of Japan, 2022, 1–40, https://www.cas.go.jp/jp/siryou/221216anzenhoshou/nss-e.pdf.

^[74] Ministry of Foreign Affairs, Japan, “Official Security Assistance,” Ministry of Foreign Affairs of Japan, 2024, https://www.mofa.go.jp/fp/ipc/page4e_001366.html.

^[75] Helen Flores, “Philippines to Receive Coastal Surveillance Radar System from Japan,” Philstar, July 9, 2024, https://www.philstar.com/headlines/2024/07/09/2368895/philippines-receive-coastal-surveillance-radar-system-japan.

^[76] Anna Felicia Bajo, “PCG Chief: Marcos OK'd Acquisition of 5 97-Meter Boats from Japan,” GMA, November 7, 2024, https://www.gmanetwork.com/news/topstories/nation/926301/pcg-chief-marcos-ok-d-acquisition-of-5-97-meter-boats-from-japan/story/.

^[77] “Philippines Eyes Defense Pacts with France, Canada, New Zealand, Says Minister,” TV5, July 22, 2024, https://news.tv5.com.ph/articles-you-might-like/read/philippines-eyes-defense-pacts-with-france-canada-new-zealand-says-minister#google_vignette.

^[78] Trajano, "Japan-Philippines Strategic Partnership: Converging Threat Perceptions."

^[79] Richard Javad Heydarian, "Philippines-Japan security pact puts China on notice." The Interpreter, 2024, https://www.lowyinstitute.org/the-interpreter/philippines-japan-security-pact-puts-china-notice

• International Affairs
• India
• The Pacific, East and Southeast Asia
• China’s expansion
• Exclusive Economic Zone (EEZ)
• Indo-Pacific
• Japan
• maritime security
• Philippines
• rules-based order
• South China Sea
• strategic partnership
• West Philippine Sea

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