China and Cambodia have officially launched the Yunyang Port Support and Training Center, a new joint facility located near Cambodia’s Ream Naval Base, marking a significant step forward in their growing defense partnership. The center began full operations on April 5, 2025, with both Chinese and Cambodian personnel stationed at the site to handle daily operations and coordination.
Announced by China’s Ministry of National Defense, the Yunyang Port facility is described as the product of “mutual respect and equal consultation” between Beijing and Phnom Penh. Officials from both sides stress that the center is intended to provide practical military cooperation, enhance technical training, and support public security efforts. Importantly, both governments have underscored that the center is “not directed at any third party” — a line clearly aimed at easing regional anxieties.
Yet, the timing, location, and scale of this development leave little doubt about its wider significance, especially against the backdrop of rising tensions in the Indo-Pacific.
The Yunyang Port Support and Training Center sits in close proximity to the Ream Naval Base — a Cambodian military facility that has drawn intense scrutiny from defense analysts and foreign governments over the past several years.
Satellite imagery published in 2023 first revealed major expansion works at Ream, including a large dry dock facility, new piers, and significant infrastructure upgrades. Of particular note was the construction of a pier reportedly capable of hosting aircraft carriers or large amphibious assault ships — vessels far beyond the current needs or capabilities of Cambodia’s small navy.
Such upgrades, analysts say, suggest a dual-use strategy: a facility that nominally serves Cambodian interests but can be rapidly scaled for use by China’s People’s Liberation Army Navy (PLAN) if required.
Geography is a crucial part of this story. The expanded Ream Naval Base and the nearby Yunyang Port facility lie just outside the mouth of the Gulf of Thailand, providing easy access to the South China Sea. But more importantly, they are within strategic striking distance of the Malacca Strait — the world’s busiest shipping lane, and a vital artery for global energy flows.
Roughly 60% of China’s imported oil passes through the Malacca Strait. This bottleneck — long referred to by Chinese strategic thinkers as the “Malacca Dilemma” — represents a critical vulnerability for Beijing, particularly in any scenario involving a U.S.-led naval blockade.
With its growing network of bases, ports, and logistics hubs stretching across the South China Sea and into the Indian Ocean, China is clearly working to ease that vulnerability. The new Yunyang Port center is just the latest piece of that expanding infrastructure puzzle.
Both Phnom Penh and Beijing insist that their cooperation is entirely transparent and defensive in nature. Cambodia’s Prime Minister Hun Manet has emphasized that the country’s constitution prohibits the establishment of foreign military bases on Cambodian soil.
However, critics argue that the line between “base” and “logistics hub” is increasingly blurred. “China doesn’t need to fly a flag over Ream Naval Base to benefit from its capabilities,” says a Southeast Asia defense analyst based in Singapore. “It just needs access — and from what we’ve seen, it appears to have that.”
U.S. officials have expressed longstanding concerns over China’s military presence at Ream, suggesting that it could provide Beijing with its first dedicated naval facility in Southeast Asia — a major development in its broader Indo-Pacific strategy.
An anonymous U.S. defense official was quoted in regional media saying: “The scale of construction at Ream exceeds any plausible Cambodian requirement. This looks far more like a forward operating support site for PLAN than a local naval upgrade.”
For Southeast Asian nations, the deepening China-Cambodia military relationship sends a clear signal: Beijing is consolidating its foothold on the western side of the South China Sea.
Vietnam, which shares historical tensions with both Cambodia and China, has been especially wary. Analysts suggest that Hanoi views the Ream developments as a potential threat to its own maritime security and freedom of navigation in the region.
Thailand and Malaysia, while officially silent, are likely watching closely. Both nations sit near the Malacca Strait, and any Chinese military expansion in the region raises obvious strategic calculations.
Indonesia, with its sprawling archipelago and major energy transport routes, is also assessing the shifting balance of power.
For Phnom Penh, aligning closely with China offers both rewards and risks.
On the one hand, Chinese investment has poured into Cambodia over the past decade, funding everything from infrastructure projects to real estate and energy developments. Military cooperation is a natural extension of that relationship.
The joint training center at Yunyang Port provides Cambodian naval personnel with access to advanced Chinese technical expertise and equipment, strengthening their operational capabilities.
On the other hand, Cambodia risks becoming overly dependent on Beijing — a concern that some in the region and within Cambodia itself have raised quietly.
By allowing Japan’s naval vessel to visit Ream soon after its expansion — as Cambodian officials have stated — Phnom Penh may be attempting to demonstrate that its ports remain open to multiple partners, not just China.
The Yunyang Port development fits into a larger pattern of Chinese activity in the Indo-Pacific.
Beijing has invested heavily in port facilities, naval logistics hubs, and infrastructure projects across the region under the Belt and Road Initiative (BRI). From Gwadar in Pakistan to Hambantota in Sri Lanka and Djibouti in East Africa, China is assembling what some have called a “string of pearls” — a network of facilities that could support military operations if needed.
Ream Naval Base and the Yunyang Port center appear to be Southeast Asia’s contribution to that network.
“China is playing a long game here,” says an Asia-Pacific security analyst. “Every port, every logistics hub, every training center gives the PLAN more flexibility and reach. It’s about creating options, not necessarily launching immediate operations.”
As operations begin at Yunyang Port, the next few months will be closely watched.
- Will Chinese warships make regular calls at Ream or Yunyang?
- How will the U.S., Australia, and Japan respond to the growing Chinese presence?
- Will Cambodia seek to balance China’s influence by deepening ties with other regional players?
- Could Vietnam or other ASEAN members ramp up their own naval modernization in response?
Already, the U.S. has stepped up its naval engagements in the region, conducting freedom of navigation operations (FONOPs) in the South China Sea and increasing defense ties with the Philippines and Vietnam.
The opening of the Yunyang Port Support and Training Center marks a new phase in China-Cambodia defense cooperation. While both governments frame the development as peaceful and focused on public security, the strategic implications are clear.
For China, it represents another step in securing critical sea lanes and projecting power in Southeast Asia. For Cambodia, it offers both enhanced military capabilities and deeper dependence on its largest foreign patron.
