Philippines and US Conduct Largest Combined Naval Drill in South China Sea, Amid Escalating Chinese Harassment

Background

The Philippines' relationship with China in the South China Sea has been characterised by a cycle of escalating confrontations, diplomatic protests, and strategic uncertainty since the International Tribunal for the Law of the Sea issued its 2016 arbitration ruling invalidating Chinese claims within the nine-dash line as inconsistent with the United Nations Convention on the Law of the Sea. China rejected the ruling, and the Duterte administration from 2016 to 2022 adopted an accommodationist approach that de-emphasised the tribunal's findings in exchange for Chinese infrastructure investment commitments, most of which were not fulfilled. The Marcos administration that took office in June 2022 shifted Philippine strategy toward a more assertive defence of its EEZ rights, resuming resupply missions to the BRP Sierra Madre grounded ship at Second Thomas Shoal and publicly disclosing Chinese coast guard interference through official statements and released video footage. The resupply missions to Second Thomas Shoal, where a small contingent of Philippine marines is stationed as a sovereignty marker on the deliberately grounded vessel, have become the central operational focus of Philippine-Chinese friction, with Chinese coast guard and maritime militia vessels repeatedly attempting to block, water-cannon, and laser-target Philippine coast guard and navy escort vessels. The Philippines' public disclosure strategy, which differs from the quiet diplomacy that previous governments favoured, has attracted international attention and solidarity, with the US affirming that Philippine vessels operating in the Philippines' EEZ are covered by the US-Philippines Mutual Defense Treaty.

Exercise Details

Exercise BALIKATAN-MARITIME 2026, held from October 12 to 16, is the latest iteration of the bilateral US-Philippines exercise programme expanded under a 2023 agreement that increased the number of annual exercise days, the number of participating platforms, and the permissible geographic scope to include areas within the Philippines' exclusive economic zone that had previously been avoided for sensitivity reasons. The 2026 edition was the largest in the programme's history by vessel count and personnel numbers. The Philippine Navy contributed 22 vessels including its two Hamilton-class frigates and a new Israeli-designed corvette acquired in 2025, while the US 7th Fleet contributed 20 vessels including the Arleigh Burke destroyer USS Ralph Johnson and a Los Angeles-class submarine. The exercise was structured around three scenario phases. Phase one tested convoy escort procedures for vessels resupplying remote outposts, explicitly modelling the Second Thomas Shoal situation with simulated adversary interdiction. Phase two conducted combined anti-submarine warfare training in the Sulu Sea, including a coordinated attack exercise against a simulated adversary submarine operating in Philippine territorial waters. Phase three conducted live-fire anti-ship missile events using Philippine-operated BrahMos supersonic cruise missiles and US Harpoon Block II missiles launched from surface and air platforms. Australia's contribution of P-8A Poseidon maritime patrol aircraft for the exercise is significant as it marks the first direct Australian military participation in the BALIKATAN programme and reflects the alignment of Australian, Filipino, and US interests in South China Sea freedom of navigation and overflight.

• 42 vessels, 12,000 personnel in BALIKATAN-MARITIME 2026, October 12-16.
• Phase 1: convoy escort procedures modelling Second Thomas Shoal resupply.
• Phase 2: combined anti-submarine warfare in the Sulu Sea.
• Phase 3: live-fire BrahMos and Harpoon anti-ship missile events.
• Australia contributed P-8A aircraft; Japan provided surveillance intelligence.

Chinese Response and Regional Implications

China's Ministry of National Defense condemned the exercise as 'a provocative act that deliberately inflames tensions in the South China Sea' and dispatched additional coast guard and naval vessels to the vicinity of the exercise area, though these did not directly interfere with the exercise within the Philippines' EEZ. Chinese state media characterised the live-fire events as 'reckless behaviour that threatens regional stability and civilian shipping', a characterisation that Philippine defence officials rejected as hypocritical given documented Chinese coast guard interference with civilian vessels. ASEAN's response was fragmented, reflecting the diversity of member states' relationships with China: Vietnam expressed quiet support for the exercise while Malaysia and Indonesia maintained public neutrality, and Cambodia issued a statement echoing Chinese concerns about external power military activities in the region. The exercise's strategic significance extends beyond its immediate deterrence value because it demonstrates the operational integration that Philippines-US military cooperation has achieved under the Marcos administration's defence-forward posture. The Second Thomas Shoal resupply protection drills in particular provide real-world training for scenarios that could rapidly escalate if China were to use significant force to prevent Philippine resupply. The US affirmation that the Mutual Defense Treaty covers Philippine government vessels and aircraft in the Philippines EEZ, restated during the exercise, creates an escalation ladder that both Manila and Washington have committed to, but whose rungs have not been tested in a genuine confrontation.

Sources

• Reuters
• Philippine Department of National Defense
• US Indo-Pacific Command
• South China Morning Post
• Benar News