Navigating the middle: Japan-Cambodia relations and the challenge of geopolitical competition

Navigating the middle: Japan-Cambodia relations and the challenge of geopolitical competition

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WRITTEN BY DR SOPHAL EAR

29 May 2025

Fifty years after the Khmer Rouge seized power in Cambodia, the country finds itself once again at a pivotal moment: this time not because of internal revolution, but due to the intensifying geopolitical contest between the United States and China. In this fraught regional environment, Japan stands out as a critical, albeit often understated, partner.

Japan’s long-standing engagement with Cambodia, rooted in diplomacy, development, and peace building, positions it uniquely as both a counterbalance and a complement to Cambodia’s increasingly China-centred foreign policy. Cambodia’s challenge today is how to assert agency in a landscape dominated by great-power rivalry. For Tokyo, the question is how to preserve its influence amid an increasingly crowded field.

Working together allows Cambodia to hedge its bets amid superpower rivalry, while giving Japan a foothold to promote stability and liberal values in mainland Southeast Asia without overt confrontation. More recently, Tokyo has also signaled its strategic intent through defense diplomacy, including a naval visit to Cambodia’s Ream base — marking a subtle, but unmistakable challenge to China’s exclusive influence.

A historical arc of engagement

Japan’s relationship with Cambodia dates back to the pre-war era but was most consequentially re-established after the signing of the 1991 Paris Peace Agreements. Japan played a central role in Cambodia’s post-conflict reconstruction, contributing more than USD 200 million to the United Nations Transitional Authority in Cambodia (UNTAC), making it the second-largest donor after the United States. It has continued to provide substantial Official Development Assistance (ODA), with cumulative aid surpassing USD 2.5 billion as of 2023 — more than any other bilateral donor besides China.

Over the past three decades, Japan has helped build roads, bridges, schools, and institutions such as courts, ministries, and universities. Unlike China’s large-scale investments in real estate, ports, and casino zones like Sihanoukville — often criticised for their lack of transparency and ties to corruption — Japan’s aid has largely emphasised soft infrastructure: governance reform, human resource development, and institutional strengthening. This has earned Japan a reputation of trustworthiness and neutrality in Cambodia, though Tokyo has typically eschewed overt political pressure, even as Phnom Penh has slid deeper into authoritarianism, as documented by Human Rights Watch and Freedom House.

Cambodia offers a litmus test: if Japan can sustain influence there, it may do so across mainland Southeast Asia.

Cambodia and Japan elevated their ties to a Strategic Partnership in 2013. This label signalled a shared interest in peace and development but stopped short of full alignment on key geopolitical issues. Tokyo has tried to leverage this relationship to increase Cambodia’s support for international norms, including the rule of law and maritime security, but Phnom Penh has often sided with Beijing on divisive regional matters.

Take, for instance, ASEAN’s failure to issue a joint communiqué condemning China’s activities in the South China Sea. Cambodia has been accused multiple times of blocking consensus, to Beijing’s benefit. This stance has tested Tokyo’s patience, especially as it seeks Southeast Asian support for its Free and Open Indo-Pacific (FOIP) framework.

Nevertheless, Japan has maintained its policy of constructive engagement. In February 2024, Japanese Foreign Minister Yōko Kamikawa visited Phnom Penh to reaffirm bilateral cooperation. Discussions focused on human resource development, digital connectivity, and climate change resilience. The visit also marked Japan’s continued interest in helping Cambodia navigate the political fallout of US tariffs and scrutiny related to Chinese “transhipment” through Cambodian territory.

Cambodia’s foreign policy dilemma

Cambodia’s foreign policy is increasingly constrained by structural dependence. Nearly 40 per cent of its public debt is owed to China. Chinese firms dominate the construction and energy sectors, accounting for over 70 per cent of foreign investment in these areas. Politically, Beijing has served as a vital shield, vetoeing or weakening resolutions at the United Nations Human Rights Council and providing diplomatic cover amid international criticism.

This dependency amounts to what many analysts call a “debt trap”, though the term remains contested. While China has yet to enforce punitive measures, the sheer volume of lending and Phnom Penh’s limited repayment capacity gives Beijing significant leverage, especially in shaping Cambodia’s strategic decisions. But this embrace is not without cost. Cambodia’s tilt toward China has triggered countermeasures from Western partners. The European Union withdrew some trade preferences under the “Everything But Arms” scheme due to democratic backsliding. The US has imposed sanctions on military figures and now, under a second Trump administration, appears poised to revive a harsh reciprocal tariff regime targeting Cambodian exports.

It is in this context that Cambodia must recalibrate. Japan offers a model of partnership that is less domineering and more rooted in mutual benefit. It does not demand allegiance, but its leverage also depends on the degree to which Phnom Penh is willing to diversify its relationships. Thus far, economic reality has tethered Cambodia closely to Beijing.

Cambodian Prime Minister Hun Manet has attempted to recalibrate foreign policy rhetoric. While the fundamentals of close alignment with Beijing remain, Phnom Penh now speaks of “multi-vector” diplomacy — balancing between great powers to secure national interest. Japan’s consistent and low-key engagement offers an important lever in this strategy.

Can Japan compete?

From Tokyo’s perspective, sustaining influence in Cambodia is about more than bilateral ties — it’s about preserving space for liberal internationalism in mainland Southeast Asia.

But Japan faces limitations; it lacks the economic scale and political assertiveness of China. Its ODA, while substantial, cannot match the raw cash of China’s Belt and Road Initiative. For example, while Japan’s ODA to Cambodia has averaged roughly USD 100 million annually, Chinese-backed investments and loans regularly top USD 1 billion per year.

What Japan can offer, however, is credibility and capacity-building. Japan International Cooperation Agency’s (JICA) training of over 3,000 Cambodian civil servants since 1993, hundreds of scholarships for Cambodian students to study in Japan, and support for judicial and electoral reform have lasting effects. Cambodian civil society leaders, development experts, and international donors see these efforts are higher in quality and longer-term in orientation compared to the often transactional nature of Chinese assistance.

Cultural diplomacy also plays a role: the Japan-Cambodia Kizuna Festival and the enduring popularity of Japanese pop culture and language studies help foster pro-Japan sentiment among youth. Japanese language enrolment in Cambodian universities has grown steadily over the past decade, contributing to grassroots goodwill. That said, China’s cultural influence has expanded in parallel: tens of thousands of Cambodians now study Mandarin, and the soft side of the Belt and Road Initiative — including scholarships to Chinese universities and all-expense-paid junkets — continues to generate strong appeal.

The annual State of Southeast Asia surveys conducted by the ISEAS-Yusof Ishak Institute consistently show that Japan is the most trusted major power in the region, including Cambodia. In the 2025 survey, 66.8 per cent of ASEAN respondents expressed confidence that Japan would “do the right thing” for global peace, security, prosperity, and governance — an increase from 58.9 per cent in 2024. Cambodia’s trust in Japan was notably high at 73.8 per cent, ranking among the top in the region.

A potentially powerful new tool is defence diplomacy. In April 2025, two Japanese warships docked at Ream Naval Base — the first foreign naval visit since China funded the base’s controversial upgrade. While Japan insists the visit was symbolic, it sends an unmistakable message: the base is not exclusively under Beijing’s sway. The symbolism lies in asserting Japan’s strategic presence and Cambodia’s openness to non-Chinese partners. Such gestures could give Tokyo more leverage in the evolving regional security conversation.

To be sure, a less charitable interpretation could see Japan’s port of call to Ream, along with a Vietnamese People’s Navy patrol ship three-day visit on 27 April, as performative gestures aimed at softening accusations of Chinese exclusivity. The timing of these visits has not altered core international apprehensions that China has a special hold on the base. The United States, in particular, remains wary of potential violations of Cambodia’s constitutional prohibition on foreign military bases. ASEAN neighbors, while more diplomatically reserved, are monitoring the situation closely given the precedent it sets in the South China Sea neighbourhood, where overlapping territorial claims and great power competition already create a volatile security environment. Overall, the hosting of these visits serves primarily as diplomatic theatre, aimed at projecting openness, rather than signaling any genuine shift toward multilateralisation at Ream.

Cambodia’s agency in a tight space

To observers, Cambodia may seem like a pawn between China and the West. But this underestimates the country’s strategic agency. Historically, Cambodian leaders have sought to play external powers off against one another to extract concessions while avoiding excessive dependence on any single patron. For example, during the Cold War, Sihanouk leveraged US, Soviet, and Chinese aid simultaneously under a policy of non-alignment, and more recently, Hun Sen balanced Western donors against Chinese investments to maximise strategic flexibility.

The current leadership appears eager to sustain this balancing act. A case in point: despite deep economic ties with Beijing, Cambodia restored full military and diplomatic relations with Vietnam and welcomed a Japanese naval visit to Ream Naval Base in April 2025 — gestures that subtly counterbalance Chinese dominance and reflect deliberate diplomatic calibration rather than passive alignment. Hun Manet has also increased outreach to ASEAN neighbours, and emphasised the importance of “independence and non-alignment”. Japan fits into this vision as a stabilising middle power — a friend to all, enemy to none.

Cambodia’s ability to manoeuvre is shrinking. Its garment sector is heavily reliant on US and European markets, which together accounted for over 60 per cent of Cambodia’s apparel exports in 2022, while its production inputs and capital inflows are increasingly Chinese. Indeed, China supplied approximately 60 per cent of Cambodia’s knitted fabric and cotton imports in 2023, underscoring the garment sector’s reliance on Chinese raw materials. Concurrently, China remained Cambodia’s largest source of FDI, contributing about 45.6 per cent of total inflows that year.

Should the US escalate tariffs (aid has already been decimated), and should China restrict future lending or demand political loyalty in return, Phnom Penh’s space to chart an independent course will narrow. For Cambodia, the next phase must be about building strategic value. This means strengthening internal governance, reducing vulnerability to external shocks, and asserting a vision for regional integration that does not merely echo the ambitions of others.

For Japan, the task is to deepen engagement without triggering Cambodian defensiveness. This means not just funding infrastructure, but also supporting legal and institutional reforms through capacity-building with the Ministry of Justice, backing anti-corruption training programs, and funding civil society organisations through JICA and The Asia Foundation. Promoting youth-led innovation by expanding startup incubators like the Cambodia-Japan Cooperation Center (CJCC), offering technical exchanges in green technology, and investing in climate-resilient agriculture and renewable energy projects that target communities most affected by environmental degradation would also be valuable efforts. Ultimately, Japan’s Indo-Pacific strategy will be judged not by speeches or naval visits, but by its ability to provide meaningful alternatives to China’s model. Cambodia offers a litmus test: if Japan can sustain influence there, it may do so across mainland Southeast Asia.

DISCLAIMER: All views expressed are those of the writer and do not necessarily represent that of the 9DASHLINE.com platform. 

Author biography

Dr Sophal Ear is Associate Professor at the Thunderbird School of Global Management at Arizona State University. He is President of the International Public Management Network and Vice-Chair of the Public Policy & International Affairs Program. Image credit: Wikimedia Commons/Alex Schwab.