South China Sea: Hanoi and Manila’s strategies share one weakness

Vietnam’s quiet diplomacy and loud protests from the Philippines mask the same reliance on Chinese clean energy.

Hanh Nguyen

15 October 20264 min read

Vietnam and the Philippines are often portrayed as taking different approaches to the South China Sea disputes. Vietnam is said to favour a quiet approach based on bilateral diplomacy whereas the Philippines is seen as adopting a high-profile posture centred on international law and transparency.

But a closer look at what Hanoi and Manila have done this year reveals more convergence.

Both countries have used diplomatic and legal measures alongside more hard power approaches such as strengthening their physical presence and expanded security cooperation with key partners.

Yet Vietnam and the Philippines also face a similar long-term constraint in their South China Sea strategies – a deepening dependence on China-led renewable energy supply chains without effective industrial strategies.

These developments can gradually constrain Hanoi’s and Manila’s strategic autonomy.

Vietnam’s approach combines restrained public messaging and legal diplomacy, accelerated upgrades of outposts, and calibrated security cooperation with key partners. In March 2026, Vietnam made a statement (Opens in new window) to protest China’s land reclamation activities at Antelope Reef in the Paracel Islands, but it avoided direct reference to China. In its comment (Opens in new window) on the 10th anniversary of the 2016 South China Sea arbitral tribunal award, Hanoi reaffirmed a preference for peaceful resolution of disputes in accordance with international law and emphasised the United Nations Convention on the Law of the Sea as the sole legal basis for defining maritime entitlements.

Hanoi simultaneously accelerated (Opens in new window) its outpost upgrades across 18 reefs in the Spratly Islands, including upgrading ports, runways, military facilities and communications arrays, purportedly to improve its maritime domain awareness and consolidate its presence in the disputed areas. Vietnam also strengthened security cooperation with key partners, including upgrades to its strategic partnership with the Philippines (Opens in new window) and India (Opens in new window), and a Joint Vision Statement on Defence Cooperation with Australia (Opens in new window). But the official statements did not reveal the exact type of agreed cooperation.

The Philippines administered Thitu Island in the South China Sea, 5 February 2025 (Planet Labs PBC)

The Philippines has pursued a strategy with similar components, but with a heavy emphasis on high-profile public and legal diplomacy, backed by outpost upgrades and expanded security cooperation with extra-regional powers. Manila marked the 10th anniversary of the arbitration award with statements (Opens in new window) that directly referenced the award as affirming the Philippines’ maritime entitlements under international law. The Philippines also issued a joint statement (Opens in new window) with 13 other countries that described the award as “final, legally binding and definitive” on maritime entitlements and claims, and explicitly opposed China’s assertions in the South China Sea, including those based on “historic claims”.

The Philippines has filed 39 diplomatic protests (Opens in new window) against China this year until September, demonstrating against activities by the Chinese Coast Guard and other Chinese maritime forces. A recent confrontation (Opens in new window) between the Philippine Navy personnel and the Chinese Coast Guards near Second Thomas Shoal led to the summoning of each country’s ambassadors to protest the incident.

But the Philippines also employs hard power. It extended (Opens in new window) the runway on Thitu Island and expanded the port on Nanshan/ Lawak Island to support docking capabilities and enforcement operations. These measures are underpinned by intensified defence cooperation with the United States through the addition of four new sites (Opens in new window) under the Enhanced Defence Cooperation Agreement and the introduction of NMESIS anti‑ship missile system (Opens in new window) and Typhon Mid‑Range Capability launcher (Opens in new window) in exercises. Manila recently signed an Acquisition and Cross Servicing Agreement with Tokyo and is slated to receive a European Peace Facility assistance (Opens in new window) measure worth €15 million to strengthen maritime domain awareness.

So while Vietnam favours restrained diplomacy given its current situation – lacking an alliance, strong political and economic ties with China and an inclination to avoid direct confrontation with Beijing – the Philippines, in contrast, takes advantage of its legal victory and uses its role in emerging security cooperation with the US and Japan regarding a Taiwan contingency.

Yet both strategies face the same constraint. On the Philippine side, domestic political shifts (Opens in new window) may sway the short term direction but in the long term both Vietnam and the Philippines are accelerating their energy transition. Their efforts have also made them dependent on China’s clean energy supply chains. This could shape their South China Sea strategy.

The Philippines (Opens in new window) has become China’s second-largest solar panel market, and Chinese firms also made inroad into the Philippine markets with engineering, procurement, and construction contracting and direct acquisition of manufacturing capacity. In Vietnam, Chinese firms hold a dominating position (Opens in new window) in similar renewable energy contracts and supply chains, providing components for wind turbines and EV vehicles.

Deep integration is likely given China’s dominant position in the clean energy sector and a convergence of interests regarding energy transition. Closer integration might create powerful vested interests within the Philippines and Vietnam, which might encourage further linkages with China while resisting more confrontational moves in the South China Sea.

These developments can gradually constrain Hanoi’s and Manila’s strategic autonomy. Both Vietnam and the Philippines would be able to preserve some of their autonomy by developing industrial strategies (Opens in new window) that include local content requirements, facilitate technology transfer and encourage upstream integration in supply chains.

This article was supported as part of a grant from the ANU Philippines Institute. The views expressed are those of the author.

About the author

Hanh Nguyen

Ms Hanh Nguyen is a scholar on Asia-Pacific security architecture, crisis governance, economic security and Southeast Asia, with a focus on Vietnam.

Topics

South China Sea Vietnam Philippines China Energy & resources