Japan’s Growing Hard-power Profile: Implications for Southeast Asia

INTRODUCTION

Since the end of World War II, Japan’s influence in Southeast Asia has been shaped primarily by its economic weight, diplomatic engagement, development assistance, and cultural appeal. These factors have underpinned Tokyo’s consistent standing as the region’s most trusted major power, as reflected in the ISEAS–Yusof Ishak Institute’s State of Southeast Asia annual surveys (SSEA). Yet, even as this trust endures, the mainstay of Japan’s influence – its economic and technological prowess – has declined; the region’s economic gravity has instead shifted towards China, with South Korea also emerging as a competitive techno-industrial force. While regional surveys indicate that Japan remains influential, China is increasingly viewed as the most important partner for ASEAN’s future and economic growth.

Yet, the story of the rising sun is far from over. Japan is emerging as a potentially consequential hard-power player by steadily reshaping its strategic profile through increased deterrence capabilities and expanded security networks. Tokyo’s transition is incremental, calibrated, and shaped by systemic shifts in the regional and global security environment that have sharpened its threat perceptions. These dynamics unfold against the backdrop of Japan’s long-running effort to reconcile its post-war identity as a peace-oriented nation – anchored in a pacifist constitution and a populace deeply wary of war-making – with its gradual shift towards a more militarily capable and deterrence-focused security posture. This article examines this transition in Japan and its potential implications for Southeast Asia.

JAPAN’S CHANGING STRATEGIC OUTLOOK AND HARDENING SECURITY POSTURE

Japan’s strategic outlook has gradually shifted from an emphasis on shaping global governance through economic influence and multilateral engagement towards a more pragmatic realpolitik approach, driven by structural changes in its external environment. China’s rapid military build-up has fuelled its assertiveness in the East and South China Seas. Russia’s invasion of Ukraine laid bare the erosion of the rules-based international order. North Korea’s nuclear and missile threats continue unabated, and Pyongyang’s deepening ties with Moscow – alongside tightening Sino-Russian alignment – have accentuated Tokyo’s threat perception. Furthermore, the dramatic shift in US foreign policy under Trump 2.0 has placed unprecedented pressure on allies like Japan to shoulder greater defence responsibilities.

Japan’s embrace of the “Free and Open Indo-Pacific” concept, conceived by Prime Minister Shinzo Abe in 2012, signalled the beginning of this strategic turn. Described as “Asia’s Democratic Security Diamond”, linking the Pacific and Indian Oceans, the concept was shaped by the imperative to counterbalance China’s power by anchoring a rising India within the constellation of US allies and like-minded partners. Arguing that Tokyo “should play a greater role in preserving the common good in both regions”, the Abe government in 2014 approved a reinterpretation of the constitution permitting the participation of the Japan Self-Defence Force (JSDF) in collective self-defence missions when an ally is under attack.

Successive Japanese governments have reinforced this trajectory, providing policy substance, political ballast, and institutional infrastructure to Japan’s growing defence-security profile. The Kishida government’s 2022 National Security Strategy (NSS) and National Defence Strategy (NDS) were watershed documents, stating unambiguously that “Japan’s security environment is as severe and complex as it has ever been since the end of World War II (WWII)”, while asserting that Japan “will not tolerate unilateral changes to the status quo by force”, and must “fundamentally reinforce its defence capabilities”. Central to this shift were the development of counter-strike capabilities through the acquisition of Tomahawk cruise missiles and home-grown long-range missiles, and the increase in defence spending from the long-held cap of approximately 1% of GDP to 2% by 2027.

The current Sanae Takaichi government has accelerated this timeline by two years, with the 2% target now slated for fiscal year 2025. As Abe’s ideological heir, Takaichi is expected to fast-track Japan’s security evolution, aided by the alignment within the ruling coalition between her Liberal Democratic Party and the Japan Innovation Party on the imperative to strengthen defence capabilities, in contrast to the more pacifist stance of the previous Komeito partner. Barely a month into office, she has advanced plans to establish a national intelligence agency, revise the 2014 Three Principles on Transfer of Defence Equipment and Technology by 2026 to remove restrictions on Japan’s lethal weapons export and expand domestic weapons manufacturing, potentially enabling Japanese firms to become significant global arms players. Furthermore, Japan’s arms imports surged by 155% between 2019 and 2023 (Figure 1), becoming the sixth-largest weapons importer globally, reflecting its gradual emergence as a consequential security actor.

AN EMERGING DEFENCE PARTNER OF SOUTHEAST ASIA

Recognising its constitutional constraints and the sensitivities surrounding its WWII history, Japan has pursued its more hard-edged security posture in close coordination with the US and other like-minded partners, allowing Tokyo to expand its strategic footprint while managing domestic and regional perceptions. According to the Lowy Institute Asia Power Index 2024, Japan’s most significant improvement was in defence networks, where increased activity with the US and other regional partners boosted its score by 13.1 points.

For Southeast Asia, Japan’s relevance as a defence partner has risen significantly from 15^th place in 2017 to 4^th in 2025, according to the Lowy Institute’s Southeast Asia Influence Index. Japan’s defence cooperation is particularly robust with the Philippines (46.5 in the Index’s ranking), Vietnam (43.3), Indonesia (39.9), Malaysia (39.7), and Cambodia (35.6). Military exercises with Southeast Asian states have expanded steadily since 2014, mainly with maritime states such as Indonesia (18.8%), the Philippines (18.2%), Singapore (17.7%), and Malaysia (16.6%) (Figures 2 & 3). Likewise, port calls by the Japan Maritime Self-Defence Force (JMSDF) have become more routine in the region.

Japan’s provision of defence equipment to Southeast Asia has also increased in recent years, facilitated in part by the Official Security Assistance (OSA) scheme. Launched in 2022, the OSA enables Japan to supply non-lethal defence equipment to strengthen the capabilities of partner countries.

The Philippines has been the foremost beneficiary, receiving rigid-hulled inflatable boats, coastal radar systems, and air surveillance equipment to enhance its maritime domain awareness. These material contributions are complemented by a deepening 2+2 dialogue between the two countries’ defence and foreign ministries, a landmark Japan-Philippines Reciprocal Access Agreement (RAA), which entered into force in 2025, and growing strategic trilateral cooperation between Japan, the Philippines, and the US.

… Japan’s influence as an anchor state and connective hub in shaping the Indo-Pacific security architecture to balance against Chinese military power is consequential, though often understated.

Under the OSA, Malaysia has received rescue boats to support monitoring and surveillance missions, and equipment to assist ASEAN observer teams operating along the Cambodia-Thailand border. Tokyo has also delivered two patrol boats, established working-level defence consultations, and is in discussions to co-produce advanced frigates with Indonesia, signalling its intent to project Japan’s defence-industrial capability through collaborative production with partner countries.

For Vietnam, Japan has been a helpful partner in strengthening its maritime capabilities. In 2020, both countries signed an agreement for concessional loans worth US$348 million to finance the construction of six new patrol vessels for Hanoi, in addition to Japan’s donation of six used patrol boats in 2016. In 2021, an agreement was signed to transfer defence equipment and technology, leading to the transfer of two multi-purpose supply vehicles to Vietnam in 2024. Hanoi and Tokyo hold deputy ministerial-level defence policy dialogues and consultations among Air Force, Army, and Navy officers. Recently, a deputy minister-level 2+2 mechanism has been established to facilitate coordination in defence and foreign affairs.

While Japan’s defence engagements with Southeast Asia have steadily expanded, its direct defence footprint remains relatively limited, compared to Tokyo’s collaborations with other strategic partners (see the subsequent section). The OSA is modest in terms of funding and the range of military equipment provided. Besides, Southeast Asian countries have divergent threat perceptions vis-à-vis China, and are reluctant to engage in arrangements that could be seen as balancing against Beijing, circumscribing the extent of Japan’s regional hard-security cooperation.

JAPAN’S GLOBAL STRATEGIC NETWORKING

While Japan’s defence engagement with Southeast Asian countries remains formative, its parallel outreach beyond the region has more substantial strategic depth and operational cooperation; intensifying security cooperation with a broader constellation of like-minded partners in Asia and Europe, through joint exercises, defence-industrial collaboration and capability-enhancement initiatives. It is within this wider web of global partnerships that Japan is emerging as an increasingly consequential security actor, with effects that will reverberate across the Indo-Pacific landscape.

In defence-industrial collaboration, Tokyo is involved in high-end projects, such as the UK-Italy-Japan Global Combat Air Programme (GCAP) to develop a sixth-generation fighter, slated for service entry in 2035. In 2025, Australia selected Japan’s Mitsubishi Heavy Industries to build a new fleet of 11 Mogami-class frigates, valued at US$6.5 billion – the largest defence deal in Japan’s history. New Zealand has likewise signalled interest in Japan-built ships. These advances are restoring Japan’s defence-industrial momentum and market legitimacy to scale up capabilities after decades of stagnation. This trajectory could accelerate further if the Takaichi government removes restrictions on lethal weapons exports, allowing Japanese firms to compete more robustly in global defence markets.

Tokyo has also extended its transatlantic security networks. As one of NATO’s four Indo-Pacific partners (IP4), Tokyo established its dedicated Mission to NATO in 2025 and convened the first Japan-NATO dialogue on defence-industrial cooperation, focusing on emerging technologies, interoperability, and supply-chain security. With the EU, Japan launched the Security and Defence Partnership in 2024 – covering maritime security, cyber, hybrid threats, counter-terrorism, non-proliferation, and peace operations – and held the inaugural Japan-EU Security and Defence Dialogue in 2025 to operationalise these priorities. 

Japan’s deepening defence engagement with Europe is driven by the conviction that “Ukraine today may be East Asia tomorrow”. Tokyo is one of Ukraine’s leading non-lethal aid sponsors, providing around US$15 billion in aid since 2022. More broadly, Japan has worked to strategically connect the two regions by encouraging European military engagements in Asia through port calls, joint exercises, and defence agreements, aligned with its outlook that “the security of Euro-Atlantic and Indo-Pacific is inseparable”. Tokyo concluded a Reciprocal Access Agreement with the UK in 2023, is negotiating one with France, and is open to hosting the first NATO liaison office in Asia. Japan also joined France and the US in a series of maritime drills in the South China Sea in 2025, reflecting its role as an emerging node facilitating Europe’s operational presence in the Indo-Pacific. For its part, Japan is projecting its forces farther afield: in September 2025, the Japan Air Self-Defence Force conducted its first-ever fighter deployment to Europe as part of the Atlantic Eagles mission.

Closer to home, Japan’s influence as an anchor state and connective hub in shaping the Indo-Pacific security architecture to balance against Chinese military power is consequential, though often understated. Outside the US, Japan maintains the closest military ties with Australia in the Indo-Pacific. Tokyo and Canberra maintain a “special strategic partnership”, with frequent high-level engagements and regular 2+2 meetings between their defence and foreign ministers. A convergence of concern about China’s strategic footprint in Southeast Asia and the Pacific has led both countries to intensify their security partnership, culminating in the Australia-Japan RAA, which entered into force in 2023. As “Japan’s first defence treaty with an international partner since 1960,” it has facilitated over 40 joint activities, enabled the largest ever Japanese participation of over 1,500 Japan Self-Defence Forces (JSDF) personnel in Exercise TALISMAN SABRE 2025, and Australia’s inaugural participation in Exercise ORIENT SHIELD with the US and Japan. Canberra trails only the US as Tokyo’s most frequent military exercise partner since 2021 (Figure 4).

As for India, the foundations for enhanced Japan-India military logistics and information-sharing have been laid through the 2015 Agreements on Defence Equipment & Technology Transfer and Security of Classified Information, as well as the 2020 Acquisition and Cross-Servicing Agreement (ACSA). Defence-industrial cooperation is also beginning to take shape, notably through Japan’s provision of the Unified Complex Radio Antenna (UNICORN) stealth antenna system for Indian warships. This trajectory is set to gain further momentum with the 2025 Japan-India Joint Declaration on Security Cooperation, committing both sides to enhanced use of the ACSA for logistical support, greater access to each other’s facilities for repair and maintenance, more frequent visits and port calls, and expanded co-development and co-production of defence equipment and technologies.

Outside bilateral engagements with Quad partners, Japan is increasingly embedded in major minilateral frameworks to shape the Indo-Pacific security architecture even as the Quad falters under Trump 2.0. The SQUAD grouping, comprising the US, Japan, Australia, and the Philippines, has sustained traction through regular meetings and joint patrols in the Philippines’ exclusive economic zones, with ongoing discussions about formalising and potentially expanding the grouping. Japan has also deepened trilateral cooperation involving Australia, the ROK, India, France, and the US. In 2025, Tokyo, Canberra, and Washington signed an important trilateral logistics agreement enabling reciprocal naval support, including refuelling and missile reloading.

IMPLICATIONS FOR SOUTHEAST ASIA

So far, Japan’s security-defence engagements with Southeast Asia have been positively received, with minimal political backlash, largely because they have been advanced cautiously due to Japan’s own institutional constraints and with sensitivity to regional political realities. Tokyo recognises that Southeast Asian countries maintain deep economic and diplomatic linkages with China and are wary of actions that might be perceived as overtly provocative to Beijing. Tokyo’s gradual, carefully sequenced steps therefore signal incremental evolution rather than rupture in its regional behaviour.

Apart from bilateral and minilateral engagements with Southeast Asian partners, Japan remains a steadfast supporter of ASEAN-led mechanisms, as reflected in its 2025 joint statement to further implement the ASEAN Outlook on the Indo-Pacific. In 2025, Japan proposed the Japan-ASEAN Ministerial Initiative for Enhanced Defence Cooperation (JASMINE), focusing on defence exchanges, seminars, and capacity-building, reflecting Tokyo’s calibrated use of ASEAN-led platforms to build norms and trust through sustained institutional engagement.

Southeast Asians’ trust in Japan rests on its benign image, cultivated through decades of economic, diplomatic, and soft-power engagement. This trust is unlikely to erode simply because Tokyo is gradually strengthening its defence capabilities …

While ASEAN remains essential to Japan’s regional strategy, Tokyo is diversifying its strategic focus, deepening its alliance with the US, and extending military cooperation with like-minded partners, forming a broader constellation of strategic partnerships that collectively bolster its Indo-Pacific security posture. Whether Tokyo can sustain its adept balance of hard-edged defence engagements – focused on the security challenge posed by China – with its traditional support for ASEAN multilateralism, without sidelining the bloc, will be a critical test that will require increasingly sophisticated diplomacy going forward.

This balancing challenge becomes evident in Tokyo’s efforts to link the Indo-Pacific and Euro-Atlantic security theatres. While cross-regional linkages enhance Japan’s security profile and capabilities, they risk conflating two strategically distinct regions and complicating already complex security dynamics. Southeast Asian countries generally welcome the presence of external powers in the region but are wary of overly confrontational or power-centric approaches that could sideline ASEAN-led frameworks or draw them into bloc politics. In this context, Tokyo’s overtures – such as supporting NATO’s reach into Asia, or former Prime Minister Shigeru Ishiba’s proposal of an Asian NATO – appear tone-deaf to Southeast Asian strategic perceptions and overlook the nuanced, hedging approaches of Southeast Asian states, while inadvertently playing into Beijing’s narrative against Cold War mentality and NATO encroachment in Asia.

Conversely, Southeast Asia will need to navigate a delicate balance amid the increasingly fraught relationship between Japan and China. As Tokyo pursues a more forward-leaning security posture to counter China, regional countries face a stark challenge in balancing their relations with Tokyo and Beijing.

Southeast Asians have developed a remarkable degree of trust in Tokyo (Figures 5, 6, and 7), such that their views of Japan’s military role are shifting in a positive direction. The SSEA shows that the share of respondents viewing “Japan’s military power as an asset for global peace and security” rose from just 1.5% in 2020 to 10.5% in 2025, although this gain is modest relative to other pillars of Japan’s appeal. Similarly, a 2023 Japanese Ministry of Foreign Affairs survey found that 88% of Southeast Asian respondents support the JSDF’s more active role in regional peace, stability, and disaster management, suggesting a growing comfort with Japan’s regional security engagements.

The differing trust perceptions of Japan between China and Southeast Asia – and the tensions these differences generate – became visible in 2025, when Beijing launched an extensive anti-Japan propaganda campaign to mark the 80^th anniversary of the defeat of Japan in WWII. Initially focused domestically, the campaign expanded internationally after Takaichi suggested that a Taiwan contingency could pose a “survival-threatening situation” for Japan. Beijing’s subsequent response leveraged historical grievances to pressure other nations to align with its position. When asked about this issue, Singapore’s Prime Minister Lawrence Wong remarked that Singapore and Southeast Asia are “moving forward” from history and “support Japan playing a bigger role […] including on the security front.” His matter-of-fact statement was quickly politicised on social media, exposing faultlines within Singaporean society – particularly among segments heavily influenced by Chinese media. This episode underscores that Southeast Asian states will increasingly have to navigate both the pressures of Japan-China tensions and domestic sensitivities, where historical memory and external influence shape public perception in ways that complicate both domestic politics and foreign policy.

CONCLUSION

Southeast Asians’ trust in Japan rests on its benign image, cultivated through decades of economic, diplomatic, and soft-power engagement. This trust is unlikely to erode simply because Tokyo is gradually strengthening its defence capabilities: the spectre of a remilitarised Japan returning to territorial conquest is far-fetched, and the absence of shared borders, territorial disputes, or aggressive intent between Japan and the region reduces the sense of threat. For some Southeast Asian states, a stronger Japan may even serve as an implicit counterweight to China, particularly against the backdrop of flagging US engagement. Furthermore, Japan’s militarisation remains a work in progress that faces fiscal pressures, demographic challenges, strong pacifist domestic norms, and potential domestic political instability should the current Takaichi coalition falter.

Nevertheless, Tokyo must proceed with care. A re-armed Japan could evoke lingering historical memories, particularly among older generations, and such perceptions could be amplified by domestic politics or Chinese propaganda. A development to watch is the ongoing “nuclear” debate: South Korea’s plan to acquire nuclear-powered submarines with Washington’s support has triggered discussion in Japan over whether Tokyo should follow suit. If this materialises – although there is no guarantee, given Japan’s deeply ingrained nuclear taboo – it could provoke a highly assertive Chinese response, which would invoke the Southeast Asia Nuclear-Weapon-Free Zone Treaty to pressure regional states into opposing Tokyo, as it did in response to AUKUS. The region could find itself in a difficult position – not necessarily due to fear of a return of Japanese militarism, but because Tokyo’s evolving hard-power posture would further complicate regional politics and strategic calculations. Ultimately, it is the way Tokyo communicates and socialises its evolving role – through measured messaging, sustained outreach, and respect for regional sensitivities – that will determine whether or not Southeast Asia reads Japan’s growing capabilities as a stabilising and trustworthy presence. 

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This is an adapted version of ISEAS Perspective 2026/8 published on 4 February 2026. The paper and its references can be accessed at this link.