Japan, the Philippines and the United States are deepening security cooperation around the Philippines’ northern Luzon and the Luzon Strait, part of a strategic framework to strengthen deterrence along the first island chain and secure vital maritime corridors in the Western Pacific.
The partnership has accelerated since the nations agreed in 2024 to advance defense cooperation, including naval training, exercises and maritime coordination. The initiative, which links two long-standing U.S. treaty allies, represents a broader effort to formalize multilateral cooperation in the Indo-Pacific, according to Don McLain Gill, a geopolitical expert at Manila’s De La Salle University.
“For the Philippines, institutionalizing cooperation with the U.S. and Japan under one framework allows better integration, planning and operations in various domains. One domain is maritime security,” Gill told FORUM.
The first island chain, a string of archipelagoes encompassing Japan, Taiwan, the Philippines and Indonesia, is a vital line of defense for the U.S. and its Allies and Partners.
Recent exercises highlight the focus on the Luzon Strait, which separates the Philippines and self-governed Taiwan. In late February 2026, Japan, the Philippines and the U.S. conducted naval and aerial drills near the strait’s Bashi Channel under the Multilateral Maritime Cooperative Activity (MMCA) framework. It was the first MMCA held near Taiwan, which China claims as its territory and threatens to annex by force.
The channel is a strategic gateway between the South China Sea and the Pacific Ocean and a key shipping route for energy and other trade. The waterway has gained importance as China’s military intensifies operations around Taiwan, including large-scale exercises simulating a blockade of the island.
In January 2026, Manila and Tokyo signed an Acquisition and Cross-Servicing Agreement to streamline joint training and other operations by the nations’ forces.
Recent iterations of the annual Philippines-U.S. exercise Balikatan reflect the growing focus on the Luzon Strait, with drills conducted on islands such as Fuga, Calayan and Batan, which face Taiwan across the maritime corridor.
During Balikatan 2025, Philippine and U.S. forces conducted maritime security drills in the Batanes Islands while deploying missile launchers to simulate coastal defense and anti-ship operations in the strait. The exercise also included force insertions and maritime security scenarios focused on controlling sea lanes linking the South China Sea and the Pacific Ocean.
Tokyo’s growing regional influence also is shaping the trilateral partnership. “Japan has recently stepped up its leadership role in the Indo-Pacific, while also being open about the threats posed by China on the security of the first island chain,” Gill said.
“Cooperation is also seen in the technical aspect, where the U.S. and Japan are exploring capacity-building efforts with the Philippines in infrastructure, critical minerals and technology,” he said.