Are China-Philippines tensions sinking the South China Sea Code of Conduct?

On 31 May 2026, Philippine Secretary of National Defense Gilberto Teodoro Jr singled out China as the main obstacle to the Code of Conduct in the South China Sea (COC) at the sixth plenary session of the Shangri-La Dialogue in Singapore. 

In response to Teodoro’s remarks, the Chinese embassy in Singapore issued a statement on their Facebook page, reiterating Beijing’s longstanding rejection of the 2016 South China Sea Arbitration Award (2016 Arbitral Award), characterising it as “illegal, null and void, and non-binding” and asserting that China’s territorial sovereignty and maritime rights will not be affected by it under any circumstances. Most recently, the Chinese also sanctioned Teodoro Jr for making repeated “erroneous remarks”.

Intensified regional tensions amplify rhetoric

The 2026 round of diplomatic exchanges between China and the Philippines reflects the decade-long legal and strategic impasse and the hardened positions that both states have taken on the 2016 Arbitral Award. 

Substantively, the statement of the Chinese embassy in 2026 does not bear much difference from its previously expressed position on the 2016 Arbitral Award at various international forums. China’s primary procedural objections are that the Philippines unilaterally initiated arbitration without fulfilling the prerequisite of a “thorough exchange of views”, and that UNCLOS does not regulate land territorial issues, and that the Arbitral Tribunal acted ultra vires, infringing upon China’s right as a state party to UNCLOS to choose its own means for dispute settlement. 

On the merits, China specifically highlighted the tribunal’s classification of Taiping Island (Itu Aba) as a “rock” as one of the ruling’s key errors. This is noteworthy because the status of Taiping Island/Itu Aba has also been one of the tribunal’s most contested findings among international legal scholars. The sharp divide over whether Article 121(3) applies to Taiping Island/Itu Aba highlights the ambiguity of the provision and the need for greater interpretive clarity from future international court rulings.

The assertive language in recent tit-for-tat exchanges between China and the Philippines is more likely a by-product of intensified regional tensions due to increasing large-scale joint military exercises with external powers. In May 2026, the US and Philippines held their annual joint military drill — Exercise Balikatan 2026 — in the South China Sea and the Taiwan Strait, with the participation of over 17,000 personnel from seven countries, including Canada, Australia, New Zealand, France and Japan. 

The full participation of Japan in the Exercise Balikatan 2026 and their newly announced plans to negotiate maritime boundaries with the Philippines mark not only the forging of a middle-power coalition in Asian waters, but also a pivot toward more robust deterrence and cooperation through this new regional alignment within the Philippines’ defence strategy in the South China Sea. 

National interests rising to the fore

These heightened geopolitical developments have further complicated the COC talks as they point to both China and the Philippines’ firm pursuit of their long-term national interests while sidelining the broader regional imperative — peaceful and harmonious environment in South China Sea for the enhancement of regional peace, stability, economic growth and prosperity — which is also the ultimate objective of the COC that is currently envisaged as “a rules-based framework containing a set of norms to guide the conduct of parties and promote maritime cooperation in the South China Sea”. 

The COC has been in the works for over two decades ever since its first formal call for adoption in the Declaration on the Conduct of Parties in the South China Sea (DOC) in 2002. Even though no draft COC text has ever been published, the last report from 2017 indicates that the approved framework for the COC at the time, was short on details and reiterated much that was in the DOC so “the final COC might not look too different from the DOC”.  

While the 2016 Arbitral Award remains legally significant in upholding the authority of UNCLOS and shaping ASEAN’s legal and geopolitical approaches to the South China Sea, rhetoric that closely links the award to COC negotiations can be misleading. It risks reinforcing the erroneous assumption that the COC cannot be concluded unless China accepts the ruling, or that the award’s legal significance depends on ASEAN formally recognising or incorporating it into the COC.

Despite decades of negotiations, the COC continues to hold considerable value as a “political project” to which both ASEAN and China have invested significant diplomatic capital. At this stage, none of the parties stands to gain from abandoning the process.

While legitimate concerns remain over whether the eventual COC will contain commitments that go beyond those already set out in the DOC, in the current geopolitical climate, the very act of reaching an agreement could help ease tensions among claimant states by demonstrating a shared commitment to dialogue, goodwill and trust — the essential foundations for any meaningful discussion or negotiation on the South China Sea.

Looking beyond the heated political exchanges, ASEAN and China have expressed their longstanding commitment to adopting a COC in accordance with international law and UNCLOS. The path forward for the COC greatly hinges on whether their stated commitment for the negotiated COC to adhere to international law and the 1982 UNCLOS can be translated into substantive consensus on the COC’s contentious matters, where China and other ASEAN claimant states remain deeply divided.

Yet the conducive environment for COC adoption, which both sides have pledged to maintain and promote in their joint statement, appears increasingly elusive each day with growing militarisation, island building campaigns, grey zone tactics, and increasing confrontations in the SCS in recent months.

Behavioural guardrail presently more realistic aim

The dissonance between Beijing and Manila’s actions and their diplomatic rhetoric regarding the COC pose serious challenges to successful COC conclusion negotiations under the ASEAN Philippines chairmanship. Without a conducive environment for negotiations, COC talks are unlikely to yield tangible outcomes if the COC continues to be viewed as a mechanism for reconciling fundamentally incompatible territorial claims.

Given the current status quo, the most attainable COC is perhaps one that incorporates a “without prejudice” clause to safeguard the core sovereignty positions of all claimant states, while also institutionalising confidence-building measures and regular ASEAN-China consultations and reporting mechanisms. By protecting their positions through such a clause, claimant states may have greater room to make compromises in concluding COC negotiations without risking accusations of compromising their sovereignty or failing to uphold their legal claims in the South China Sea.

The rapidly evolving strategic reality in the South China Sea has shifted what a COC could realistically achieve at this point: from a set of enforceable regional norms toward a behavioural guardrail to manage escalation risks and reduce miscalculations in the South China Sea. A “without prejudice” clause in the COC may offer the pragmatic and necessary reassurance that cooperation on regional peace and stability will not impair or diminish any party’s underlying territorial claims, which are undoubtedly irreconcilable under the current environment where one side perceives the other’s freedom of navigation as a territorial violation, and vice versa.

Related: Did Japan and the Philippines expand Beijing’s reach in Taiwan’s eastern waters? | The Philippines’ ASEAN chairmanship comes at a perilous time