By Wu Qiaoxi | 2025-09-08

Sino-Bruneian economic ties are deepening, as Brunei makes choices that may affect its diplomatic autonomy.

In early August, the Chinese trenching ship Hai Yang Shi You 295 arrived at Brunei's largest port, Muara. This arrival marked the vessel's first visit to the country, where it will lay subsea pipelines for offshore oil fields. It highlights the deepening co-operation between the two nations.

Co-operating with China

The expansion of Muara Port is an even clearer sign of closer Sino-Bruneian ties. The port, jointly operated by a Chinese state-owned enterprise and the Bruneian government, will add a container terminal capable of handling 50,000-ton vessels, expand berths and upgrade existing facilities.

The project carries a total investment of 2 billion CNY ($278 million) and is scheduled for completion by the end of 2027, Xinhua reported in August. Once work ends, throughput is expected to at least double.

Expanding Muara "will significantly enhance the port's handling capacity and better serve Brunei's economic development and bilateral cooperation under the BRI [Belt and Road Initiative]," Xinhua in August quoted the Sino-Bruneian Muara Port Co. as saying.

Sources have not disclosed what debt Brunei is taking on as part of this venture.

The BRI is a Chinese initiative to build infrastructure around the world that will funnel poor countries' raw materials to China. Critics have denounced it as a debt trap for many unwitting countries that take out Chinese loans.

Running out of oil and gas

Brunei's economy has long relied on oil and gas, but its resources are projected to run out within 30 years.

In 2007 the government introduced its "Wawasan Brunei (Brunei Vision) 2035" development blueprint. Modeled after Saudi Arabia's "Vision 2030," the strategy seeks to reduce dependence on oil.

Since 2018, Wawasan Brunei 2035 has been aligned with the BRI.

Flagship projects include a petrochemical refinery and the Temburong Bridge, the longest in Southeast Asia.

During Sultan Haji Hassanal Bolkiah's February visit to China, the two countries issued a joint statement pledging cooperation in oil and gas exploration in the South China Sea.

Without disclosing locations, they agreed to "cooperate in the development of resources in mutually agreed areas."

The statement illustrates Brunei's cautious approach to the South China Sea: it has avoided directly confronting China over its "nine-dash line."

China draws the nine-dash line on maps to claim almost all of the South China Sea, even though its neighbors reject Beijing's view.

Brunei's growing economic dependence on China has undermined its position on the South China Sea, say analysts.

Brunei is making "a desperate attempt to secure opportunities from China by steadily neglecting its claims in the South China Sea," political scientist Bama Andika Putra of Hasanuddin University in Makassar, Indonesia, said in a 2024 study.

China is capitalizing "on the low-key position taken by some ASEAN countries including Brunei to buttress its own position on the South China Sea issue," Lye Liang Fook, associate senior fellow at Singapore's ISEAS–Yusof Ishak Institute, wrote on the ThinkChina site in February.

Siding with Washington on security

But when it comes to security and defense, Brunei leans clearly toward the United States. Since establishment of diplomatic ties in 1984, Washington has remained Brunei's main security partner. The two countries have long cooperated in joint exercises and exchanges, including Cooperation Afloat Readiness and Training (CARAT), Southeast Asia Cooperation and Training and the biennial Rim of the Pacific exercise.

At the end of 2024, Brunei and the United States concluded the 30th CARAT exercise, which lasted eight days.

"Building maritime relationships is what the CARAT exercise series is all about. Over the past week, the US Navy, US Marine Corps, and Royal Brunei Armed Forces trained together with the aim of further strengthening their cooperative maritime security capabilities in support of peace and stability," Rear Adm. Katie Sheldon, vice commander of the US 7th Fleet, said at the time.

In March 2024, two US Air Force F-35 Lightning II fighters landed at Brunei's Rimba Air Base. The US Pacific Air Forces described the event as "the first time a US fighter aircraft landed in Brunei" and an example of "a new model of international cooperation." Newsweek called it "another milestone in the US' increased defense engagement with nations along the first island chain."

That strategic chain includes Japan, Taiwan, the Philippines -- and Brunei.

Southeast Asian maritime nations do still regard the United States rather than China as their primary security partner, Australia's Lowy Institute said in August.

UK garrison in Brunei at risk

Still, nothing is forever in international relations.

Earlier this year, the UK-based Tony Blair Institute for Global Change underscored Brunei's strategic value.

If Beijing succeeds in deepening its influence in Brunei, it could undermine first-island-chain defenses, with grave implications for Taiwan.

Britain maintains a garrison of about 900 troops in Brunei, which a future Bruneian ruler could evict and replace with Chinese forces.

For the time being, Brunei is preserving its autonomy amid the Sino-US rivalry, but Chinese influence over Brunei is expanding and the sultan is 79. Hard choices may be coming.