Philippine Navy’s Flagship Issue Radio Challenge to Chinese Frigate

From September 11 to 13, 2025, the navies of the Philippines, Japan, and the United States carried out a Multilateral Maritime Cooperative Activity (MCA) inside the Philippines’ Exclusive Economic Zone (EEZ). The operation was described as a powerful demonstration of allied resolve, signaling a united front in the increasingly contested waters of the South China Sea.

During the drill, the Philippine Navy’s flagship, BRP Jose Rizal (FF-150), issued a radio challenge to a Chinese People’s Liberation Army Navy (PLAN) Type 054A frigate, bow number 551, which was spotted about 35 nautical miles southwest of Capones Island—squarely within the Philippine EEZ and only 7 nautical miles away from the Jose Rizal. The PLAN vessel invoked sovereign immunity and defended its presence but refrained from direct interference, underscoring the simmering tension that framed the exercise.

Forces Deployed

• Japan deployed its Ōsumi-class tank landing ship JS Ōsumi (LST-4001), capable of amphibious lift and humanitarian operations.

• The Philippine Navy fielded the BRP Jose Rizal, supported by a C-208B maritime patrol aircraft and four FA-50 light fighters from the Philippine Air Force.

• The United States Navy sent the USS John Finn (DDG-113), along with a P-8A Poseidon maritime patrol aircraft and two MH-60R Seahawk helicopters.

Together, the combined forces conducted complex operations, including division tactics, contact reporting, helicopter landing drills, and intelligence-sharing designed to enhance joint maritime domain awareness.

Strategic Backdrop

This MCA was the 11th such multilateral exercise but marked the first instance involving this scale of air-sea coordination and a real-time interaction with a foreign warship. Philippine Navy Rear Admiral Alfonso Torres stated that these activities are "no longer just drills, but the development of deterrence postures aligned with our constitutional duty to protect our exclusive economic rights."

The timing is significant: it comes weeks after the Philippines passed the Maritime Zone Act (Republic Act 12064), which formally codifies the nation’s maritime claims under international law. China, which rejects the 2016 Permanent Court of Arbitration ruling against its expansive South China Sea claims, has strongly protested the MCA, warning of "serious consequences" for what it calls "disruptive behavior."

China’s Southern Theater Command accused the Philippines of provocation and cautioned against involving external powers in regional disputes. However, the fact that the PLAN vessel avoided escalation during the exercise suggests both sides are recalibrating their tactical thresholds.

Implications for Regional Security

The inclusion of the JS Ōsumi highlights expanding operational scenarios beyond surveillance, such as contested island resupply or humanitarian deployment under conflict conditions. Meanwhile, the integration of P-8A Poseidon and C-208B aircraft showcased advanced allied surveillance and anti-submarine coordination.

For the U.S., the MCA underscored the role of the 7th Fleet, the largest forward-deployed fleet, as the backbone of its Indo-Pacific posture. For Japan, participation aligned with its growing security commitments under the Free and Open Indo-Pacific strategy. For the Philippines, it demonstrated a stronger deterrent presence in waters that remain flashpoints of sovereignty disputes.

The radio challenge against the PLAN frigate was more than a procedural exchange—it was a symbolic assertion of Philippine sovereignty, backed by allied naval power. While conducted professionally and without escalation, the exercise marked a turning point in trilateral maritime cooperation. It sent a clear message: in the Indo-Pacific’s most contested waters, allied unity, preparedness, and deterrence are shaping the new balance of power.