As the Philippines assumes the chairmanship of the Association of Southeast Asian Nations (ASEAN) in 2026, President Ferdinand Marcos Jr. faces a formidable dual challenge: advancing the nation’s maritime security interests while managing a deteriorating domestic political situation.

The convergence of these pressures will test not only Manila’s diplomatic capabilities but also ASEAN’s institutional resilience in addressing one of Asia’s most contentious geopolitical flashpoints.

The Code of Conduct (CoC) negotiations represent both the Philippines’ greatest opportunity and its most daunting challenge as ASEAN chair.

After two decades of glacial progress since the 2002 Declaration on the Conduct of Parties (DoC), the 2026 deadline for finalizing binding rules in the South China Sea has acquired existential urgency for Manila.

Foreign Secretary Ma. Theresa Lazaro’s commitment to monthly face-to-face meetings signals the Philippines’ determination to accelerate negotiations, yet history suggests that meeting frequency alone cannot overcome fundamental disagreements on core issues.

The four milestone issues — scope, definitions of self-restraint, relationship to the DoC and legal bindingness — reflect deeper structural tensions within ASEAN’s consensus-based decision-making process.

ASEAN’s diversity in approaching relations with China has consistently undermined unified positions on South China Sea matters. Countries like Cambodia and Laos, heavily dependent on Chinese investment, often resist strong language against Beijing, while maritime claimants like Vietnam and the Philippines push for more assertive stances. This internal fragmentation has historically favored China’s strategy of bilateral engagement over multilateral pressure.

For the Philippines, the stakes could not be higher.

Chinese assertiveness in the West Philippine Sea has directly affected Filipino fisherfolk — among the country’s most vulnerable populations — forcing them into less productive waters or dangerous open-sea ventures.

The repeated harassment of Philippine vessels by the China Coast Guard, including dangerous water cannon incidents, has transformed abstract sovereignty disputes into concrete threats to Filipino lives and livelihoods.

President Marcos’ 2024 warning that “silence in the face of these violations diminishes ASEAN” reflects Manila’s frustration with the regional bloc’s muted response to Chinese aggression against a member state.

The Philippines’ diplomatic success in 2024, when Vietnam, Singapore and Thailand followed Marcos’ lead in raising South China Sea concerns at the ASEAN-China Summit, demonstrates the potential for coalition-building within the bloc.

This breakthrough suggests a real probability that sustained Philippine leadership could gradually shift ASEAN’s approach from accommodation to resistance regarding Chinese maritime expansion.

However, Marcos’ domestic political crisis threatens to undermine these diplomatic gains. The flood control corruption scandal has devastated his approval ratings, while impeachment proceedings and health issues have created additional distractions from foreign policy priorities.

With more than 650 meetings planned throughout the year, including two ASEAN summits, the chairmanship demands sustained presidential attention and political capital that Marcos may lack.

The timing is particularly unfortunate given China’s likely strategy of exploiting Philippine domestic weakness.

Beijing has historically capitalized on Southeast Asian political instability to advance its territorial claims, and Marcos’ vulnerabilities may encourage more aggressive Chinese behavior in contested waters. If the Philippine president appears weakened or distracted, other ASEAN members may be less willing to support confrontational positions against China.

Despite these challenges, the Philippines retains significant advantages. The country’s geographic position, economic ties with major powers beyond China and growing security partnerships with the United States, Japan and Australia provide diplomatic leverage. Moreover, the 2026 deadline creates urgency that could work in Manila’s favor if properly mobilized.

Success will depend on Marcos’ ability to compartmentalize domestic troubles while maintaining ASEAN cohesion around Philippine priorities.

The president must demonstrate that his administration can simultaneously manage internal governance challenges and provide effective regional leadership.

If Marcos can navigate these choppy waters successfully, the Philippines could secure meaningful progress on the CoC while strengthening ASEAN’s institutional capacity to address great power competition.

However, failure risks not only Philippine interests but also ASEAN’s credibility as a relevant diplomatic actor in an increasingly contested regional order.