ASEAN’s Incremental Diplomacy in the South China Sea

The Philippines, as 2026 ASEAN chair, has pledged to conclude discussions on a Code of Conduct (COC) in the South China Sea. Despite this ambition, the path forward is fraught with challenges, including ASEAN’s institutional limitations and diverging interests among member states. Success hinges on a pragmatic approach focused on achievable gains rather than sweeping breakthroughs.

Challenges to a South China Sea Code of Conduct

While a COC represents Manila’s most anticipated maritime milestone, ASEAN’s capacity to deliver ambitious diplomatic outcomes is constrained. Diplomatic ambition often outpaces the organization’s institutional capabilities, potentially weakening its cohesion and resulting in largely declarative agreements. The accumulation of initiatives, including proposals for a Declaration on Maritime Cooperation and a second edition of the ASEAN Maritime Outlook, is stretching ASEAN’s process-oriented machinery [1].

A key obstacle is China’s increasing entrenchment in Southeast Asia. Chinese analyst Wu Shicun suggests that a COC agreement is “100 per cent not likely” to be signed in 2026, particularly with the Philippines holding the ASEAN chair, due to the likelihood of raising the 2016 arbitration ruling [3]. Beijing does not recognize the ruling, which rejected its expansive claims in the South China Sea, and has refused to participate in the arbitration process initiated by the Philippines in 2013 [4].

The Importance of Incrementalism

ASEAN’s historical successes, such as the Treaty of Amity and Cooperation in Southeast Asia and the Declaration on the Conduct of Parties in the South China Sea, demonstrate the effectiveness of incremental diplomacy. These agreements were achieved by focusing on attainable goals and avoiding politically sensitive issues. Excessive ambition, conversely, can undermine internal compromise.

The COC was never intended to fully resolve the South China Sea dispute, given ASEAN’s lack of enforcement capabilities, particularly concerning China. A more realistic approach involves prioritizing stronger intra-ASEAN capacity-building, focusing on communication, information sharing, and coordination at sea. This should precede more substantive engagement with China.

Prioritizing Practical Steps

Manila should adopt a risk-minimization approach, recognizing that improved US-China relations could potentially narrow ASEAN’s strategic space. The focus should be on preserving room for maneuver within ASEAN-led processes while building cohesive organizational capacity.

Rather than solely focusing on the COC, ASEAN should prioritize attainable advantages in areas where it possesses the capability to act. This includes:

• Forging incremental unity around common understandings of maritime discourse and cooperation.
• Improving information-sharing practices among member states, particularly those with limited capacity.
• Establishing a shared operational picture through real-time vessel reporting and incident transparency.
• Addressing specific issues through issue-specific mechanisms, such as incident prevention or voluntary moratoria.
• Expanding non-traditional maritime cooperation, such as critical underwater infrastructure protection and search and rescue cooperation.

Measuring Success in 2026

Diplomatic success in 2026 should be measured modestly. A realistic benchmark is whether ASEAN emerges from the Philippines’ chairmanship no more divided, no more overstretched, and with no less capacity than before. Prioritizing cohesive behavior and capacity diffusion represents the most credible contribution the Philippines can make to the bloc [1].