For decades, Southeast Asian nations and China have been embroiled in a complex territorial dispute over the South China Sea. The contested waters involve competing claims from China, Vietnam, the Philippines, Malaysia, Brunei, and Indonesia, with sovereignty disputes centering around various islands, reefs, and resource-rich maritime zones.
China bases its expansive claims on the Nine-Dash Line, which asserts control over nearly the entire sea. However, in 2016, the Hague Tribunal ruled that China’s claims were invalid under international law, particularly the United Nations Convention on the Law of the Sea (UNCLOS). Despite this ruling, China has continued to expand its military presence, reinforcing its stance on territorial control. Key contested areas include the Spratly Islands, Paracel Islands, Scarborough Shoal, the Gulf of Tonkin, and waters near Indonesia’s Natuna Islands.
The South China Sea holds immense economic, strategic, and geopolitical significance. It is one of the world’s busiest maritime trade routes, with an estimated $3.4 trillion in annual trade passing through its waters. The region is also vital to China, as 80% of its energy imports and 40% of its total trade rely on these shipping lanes. Beyond trade, the South China Sea is believed to contain 11 billion barrels of oil and 190 trillion cubic feet of natural gas, attracting the interest of claimant states and foreign investors. Additionally, the sea provides over 12% of the world’s fish catch, making it a crucial resource for food security across Southeast Asia.
From a military perspective, the South China Sea serves as a strategic chokepoint. Control over its islands and waters enables nations to strengthen their defenses, monitor naval activities, and project power. The region has become a battleground for influence, with global players such as the United States, ASEAN, and China vying for dominance. The U.S. conducts Freedom of Navigation Operations (FONOPs) to challenge China’s territorial claims, further escalating tensions.
ASEAN plays a critical diplomatic role in managing tensions in the South China Sea, as the dispute directly involves five of its member states: Vietnam, the Philippines, Malaysia, Brunei, and Indonesia. However, the bloc faces the challenge of balancing the interests of claimant states while maintaining regional stability and strong economic ties with China.
While ASEAN lacks military power to enforce decisions, it seeks to resolve the dispute through diplomatic negotiations and legal frameworks. Key diplomatic efforts include:
1992 ASEAN Declaration on the South China Sea: The first attempt to establish a unified regional stance, though it lacked enforcement mechanisms.
2002 Declaration on the Conduct of Parties (DoC): A milestone agreement between ASEAN and China, where both sides committed to avoiding escalation. However, the agreement is not legally binding, allowing China to continue expanding its military presence.
Ongoing Code of Conduct (CoC) Negotiations: ASEAN and China are working toward a legally binding CoC to regulate activities in the South China Sea. Progress has been slow due to China’s reluctance to accept restrictions and ASEAN’s internal divisions.
ASEAN’s primary interests in the South China Sea dispute revolve around protecting regional sovereignty, maintaining economic stability, and balancing relationships with global superpowers. While ASEAN must defend the territorial integrity of its members, it also relies on China as its largest trading partner, particularly through initiatives like the Belt and Road Initiative (BRI).
One of ASEAN’s biggest challenges is its internal divisions. While countries like Vietnam and the Philippines push for a firmer stance against China, Cambodia and Laos, which have close economic ties with Beijing, often block ASEAN statements or actions critical of China. This lack of unity weakens ASEAN’s ability to enforce agreements and allows China to exploit divisions within the bloc.
Foreign policy experts have mixed views on ASEAN’s handling of the dispute.
Dr. Tang Siew Mun, head of the ASEAN Studies Centre at the ISEAS–Yusof Ishak Institute, argues that ASEAN’s diplomatic engagement has prevented open conflict. While the 2002 Declaration on the Conduct of Parties (DoC) was a step forward, its lack of enforcement has limited its impact. ASEAN continues to push for a stronger Code of Conduct (CoC), but negotiations remain slow, with China resisting legally binding commitments.
However, Professor Carl Thayer, a Southeast Asia security expert at the Australian Defence Force Academy, believes ASEAN’s approach lacks effective enforcement mechanisms. He notes that despite diplomatic talks, China continues to build military installations and conduct naval patrols in disputed waters. “China engages in negotiations with ASEAN while simultaneously expanding its influence in the South China Sea,” he states.
Similarly, Ambassador Bilahari Kausikan, a former Singaporean diplomat, highlights ASEAN’s structural weaknesses. “ASEAN operates on consensus, and China exploits divisions within the bloc. If just one ASEAN member—such as Cambodia or Laos—sides with China, a binding agreement becomes nearly impossible,” he explains. Some experts suggest stronger legal backing through international courts could help ASEAN enforce agreements. Jay Batongbacal, a maritime law expert from the University of the Philippines, argues that ASEAN should push China to recognize international rulings, such as the 2016 Hague Tribunal decision. However, China refuses to acknowledge the ruling, and ASEAN lacks the power to enforce it.
In conclusion, ASEAN remains a critical diplomatic platform in the South China Sea dispute, but its ability to resolve the conflict is hindered by internal divisions, external pressures, and China’s growing influence. While diplomacy has prevented large-scale conflict, ASEAN must strengthen regional unity, enforce international law, and engage with global partners to ensure peace and stability in one of the world’s most contested maritime regions.