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Australia has once again reaffirmed its commitment to regional stability and maritime security through a multilateral Maritime Cooperative Activity with the Philippines and the United States, conducted within the Philippines’ Exclusive Economic Zone in the South China Sea.
The Royal Australian Navy’s guided-missile destroyer, HMAS Sydney, joined the Philippine Navy’s guided missile frigate, BRP Antonio Luna, alongside aerial assets from the Philippines and United States, in the coordinated maritime operation.
This latest Maritime Cooperative Activity (MCA) underscores the shared commitment of all three nations to uphold international law, including freedom of navigation and overflight, and ensure the region remains peaceful, open and prosperous.
“Australia and our partners share a deep and abiding commitment to the rules-based international order. This activity strengthens our ability to work together in support of regional security and sovereignty,” a Defence spokesperson said.
The operation focused on building interoperability, mutual understanding and readiness through combined training, manoeuvres and tactical coordination across participating forces. Such activities enhance the collective capacity to respond to shared challenges in the increasingly contested Indo-Pacific strategic environment.
This marks the second Maritime Cooperative Activity involving the Australian Defence Force (ADF) in 2025. On 6 February, HMAS Hobart joined forces with Japan, the Philippines and the United States for a similar operation, reinforcing a growing pattern of coordinated defence engagements across the region.
HMAS Sydney’s participation forms part of a broader regional presence deployment, a three-month mission launched in early April to maintain a near-continuous Australian naval presence across the Indo-Pacific. These deployments are designed to support peace, security and stability through persistent engagement, joint training and naval diplomacy.
Over the past several years, Australia has steadily increased its regional presence and defence cooperation in Southeast Asia, working closely with allies and partners to uphold international law and promote transparency. This includes regular deployments of Navy and Air Force assets, participation in multilateral exercises such as Talisman Sabre, RIMPAC, and Indo-Pacific Endeavour, and deeper security ties with countries like Japan, India and Indonesia.
The Philippines has emerged as a particularly important defence partner for Australia, with increased training, intelligence-sharing and capability development occurring as both nations respond to rising tensions in the South China Sea. In 2023, the two countries signed a Strategic Partnership Agreement, laying the groundwork for deeper military and strategic cooperation.
This week’s MCA sends a clear signal of continued trilateral resolve to maintain a free and open Indo-Pacific and highlights Australia’s growing role as a dependable regional security partner.
