What Cambodia Reveals About Japan’s Regional Strategy – OpEd

Much of the international discussion about Cambodia’s foreign policy often begins and ends with China.

The narrative isn’t unfamiliar. Since President Xi rose to power, Beijing has been heavily invested and has transformed parts of Cambodia’s economic landscape in which China accounts for 54% of Cambodia’s total investment while remaining as Cambodia’s largest foreign investor in 2025. This marks China as a major source of financing and also a strategic concern surrounding the Indo-Pacific that have pushed Cambodia into debates over great-power competition. Consequently, Cambodia is often portrayed as China’s client state in Southeast Asia. 

However, this narrative overlooks a more complicated reality. Despite China’s continuous growing presence, Japan remains one of Cambodia’s most influential and trusted partners. More importantly, Tokyo has maintained this position without competing with Beijing or Washington on financial scale or geopolitical pressure to keep its influences.

Even as a small state, Cambodia offers an important lesson about influence in the Indo-Pacific. At a time when regional politics is increasingly framed as a contest between the United States and China, Japan’s experience suggests that influence can still maintain through long-term partnerships, institutional trust, and pragmatic cooperation. Cambodia has become a demonstration that middle powers can remain relevant in the Indo-Pacic amidst in an era dominated by great-power rivalry. 

The Partnership That Outlasted Geopolitical Shifts

Japan’s relationship with Cambodia did not start within today’s Indo-Pacific competition. It was forged during a very different period.

In early 1990s, Japan played a significant role in Cambodia’s post-conflict reconstruction and peacebuilding efforts. Japanese personnel participated in UNTAC operations, while Tokyo has since become one of Cambodia’s most important development partners. Japan has emerged as a pivotal partner in Cambodia’s reconstruction and economic growth, and accelerating aid into the forefront of healthcare, agriculture, education, and governance. 

Japan ODA is undoubtedly the largest donor for Cambodia’s development, accounting for 20% of the total ODA inflow received by Cambodia, and between 1992 and 2018, Japan has provided the equivalent of over US$2.8 billion to Cambodia.

These efforts rarely viewed as attentions associated with major geopolitical accouchements. However, they created something more valuable particularly the building of institutional trust. 

From individual levels, many Cambodian policymakers, civil servants, engineers, academics, and business leaders have studied, trained, or work with Japanese institutions. The particular network has reinforced bilateral relations beyond just government-to-government diplomacy. 

The Significant of Cambodia-Japan Comprehensive Strategic Partnership

In 2023, Japan and Cambodia have elevated their bilateral relations to a comprehensive strategic partnership amid growing Chinese influence in 2023 to commemorate both nations’ 70-year diplomatic relationship. This signals a new phase of cooperation that extends beyond traditional development assistance. This new elevation of diplomatic ties comes with multiple endorsed cooperation on digital infrastructure, energy, defense, regional affairs, and other sectors.

Recent development demonstrates that this partnership remains active rather than symbolic. In 2025, Japan signed new ODA loan agreements supporting Phnom Penh’s water supply expansion and power transmission networks totaling $296.2 million (approx. ¥44.4 billion). In 2026, both governments launched new environmental cooperation initiatives covering climate change, waste management, biodiversity protection, and green technologies.

These cooperation initiatives may not attract dramatic headline, but they reveal a partnership that continue to evolve with Cambodia’s development priorities. 

Influence Without Pressure

What distinguishes Japan’s approach to maintain its influence is not merely what they contribute but how they do it.

China’s influence in Cambodia is often associated with large-scale investment, infrastructure financing, and strategic engagement. The United States, meanwhile, frequently frames its regional partnerships around governance, democratic values, and security concerns. 

Japan has generally pursued a different model. Rather than asking Cambodia to choose sides, Tokyo has focused on becoming a reliable and predictable partner. Japanese engagement has largely emphasized on economic development, human capital, institutional cooperation, and engagement in rule based international order. Particularly, Cambodia was the first country in Southeast Asia to officially back Japan’s Free and Open Indo-Pacific (FOIP) initiative, which was spearheaded by former Prime Minister Abe Shinzo in 2016.

This diplomatic alignment highlights Japan’s role as a trusted partner and counterweight in Cambodia’s foreign policy. 

Southeast Asian countries have repeatedly expressed a preference for strategic autonomy rather aligning with any major powers. Most countries in the region seek constructive relationships with multiple partners simultaneously. They welcome investment from China, security cooperation with the United States, and regional engagement from countries such as Japan, South Korea, Australia, and India.

Cambodia is no exception.

Despite growing perceptions that Cambodia has moved firmly into China’s orbit, Phnom Penh has continued to cultivate relations with a wide range of partners. Japan’s ability to maintain influence within this environment suggests that regional states do not necessarily view international relations as a zero-sum game.

Japan’s success in Cambodia challenges a common assumption underlying discussions of great power competition. While influence often measure through financial commitments, military presence, or strategic leverage, yet Cambodia case demonstrates that influence can also emerge from credibility and long-term consistency. 

It is observable that countries that force difficult strategic choices often generate resistance while countries that provide practical benefits while respecting local strategic autonomy may enjoy greater long-term influence. 

A New Role for Japan in the Indo-Pacific

Japan’s engagement in Cambodia extends beyond bilateral relations. Over the past decade, Tokyo has sought to play a more active role in regional order particularly the concept such as Free and Open Indo Pacific and Comprehensive and Progressive Agreement for Trans-Pacific Partnership (CPTPP) reflecting Japan’s desire to support regional stability, trade connectivity, and rule-based cooperation across the region. 

Recent Japan-Cambodia cooperation has expanded into areas increasingly linked to regional resilience and economic security. Senior officials from both countries have discussed economic security, governance challenges, organized crime, and regional stability as part of efforts to strengthen their Comprehensive Strategic Partnership. 

Traditionally, Japan was viewed primarily as a development partner, however, Tokyo is now increasingly becoming a strategic partner. This does not mean Japan is attempting to replace China’s role in Cambodia or draw Phnom Penh into a geopolitical bloc. Rather, Tokyo appears to be pursuing a more subtle objective to ensure that Cambodia remains connected to a diverse network of regional partnerships.

Tokyo’s approach to maintain regional influence aligns loosely with ASEAN’s longstanding preference for inclusivity and strategic balance. Noticeably, Japan’s recent diplomatic engagement also reflects this role. During periods of tension between Cambodia and Thailand, Japanese officials have consistently encouraged dialogue and de-escalation, illustrating that stability in the Mekong region is essential for broader regional prosperity. 

This reinforces Japan’s reputation as a stabilizing actor rather than a geopolitical competitor.

The future of the Indo-Pacific will not be determined solely by military capabilities or economic size. It will also be shaped by which countries can build trust, maintain credibility, and offer partnerships that regional states genuinely want. For more than three decades, Tokyo has remained influential not because it offered the largest investments or the strongest security guarantees, but because it consistently demonstrated reliability. 

While other states often approached Cambodia through the lens of geopolitical competition, Japan approached Cambodia through the lens of Partnership.