Australia-Philippines-U.S. maritime cooperation boosts interoperability
Australian Defence Department/Armed Forces of the Philippines
Naval and air units from Australia, the Philippines and the United States conducted a maritime cooperative activity (MCA) within the Philippines’ exclusive economic zone (EEZ) in August 2026.
It was the 19th MCA in the South China Sea, referred to as the West Philippine Sea by Manila, since April 2024, according to the Armed Forces of the Philippines (AFP).
The MCA included the Royal Australian Navy replenishment vessel HMAS Supply, its embarked MH-60R Seahawk helicopter and a Royal Australian Air Force P-8A Poseidon maritime patrol aircraft.
Also participating were the Philippine Navy frigate BRP Diego Silang and its embarked AW109 helicopter; Philippine Air Force FA-50PH and A-29B aircraft; the Philippine Coast Guard ship BRP Teresa Magbanua; the U.S. Navy littoral combat ship USS Santa Barbara and a U.S. Navy P-8A Poseidon.
The weeklong activity enhanced the forces’ maritime interoperability and operational coordination through “complex maritime and air operations designed to strengthen their capability to operate seamlessly together in support for a free, open, and secure Indo-Pacific,” the AFP said.
The Australian Defence Department said such activities underscore Canberra’s “commitment to regional and international cooperation in support of a peaceful, stable and prosperous Indo-Pacific, and reinforce our ability to respond to challenges that threaten our shared interests.”
The MCA demonstrates Australia’s commitment to uphold freedom of navigation and overflight under international law and to contribute, alongside partners, to deterring actions that undermine regional security, stability and lawful use of the maritime domain.
China arbitrarily claims most of the resource-rich South China Sea, a vital trade route, despite overlapping claims from the Philippines and other countries. An international tribunal ruled in 2016, in a case brought by Manila, that China had no legal justification for its expansive claims. Beijing ignores the ruling.
Australia reaffirms the 2016 ruling is final and legally binding on the parties, the Defence Department said.
The MCA highlights the enduring commitment of Australia, the Philippines and the U.S. to strengthen defense cooperation, enhance interoperability, and promote peace, stability and security in the Indo-Pacific.
“Throughout the activity, participating forces successfully conducted advanced maritime interoperability exercises, including communications exercises, maritime domain awareness, anti-submarine warfare, replenishment at sea, division tactics/officer of the watch maneuvers, photo exercise and fly-by operations,” the AFP said.
