De La Salle University distinguished professor Renato Cruz De Castro urged Taiwan, Japan and the Philippines to coordinate defense planning, saying they could strengthen their combined capabilities, Focus Taiwan reported.
The Oct. 20 conference in Taipei was organized by the Institute for National Defense and Security Research at the request of Taiwan’s Mainland Affairs Council (MAC). The council listed De Castro among the scholars it invited from overseas.
Focus Taiwan reported that De Castro linked his appeal to Chinese pressure along the first island chain, which includes Japan, Taiwan and the Philippines. He said cooperation could take place without a public announcement, according to the outlet.
De Castro developed the proposal in a December 2025 essay that identified the absence of a Philippine-Taiwan security partnership as a gap in a broader regional approach. He urged informal defense discussions and intelligence sharing, while saying Manila’s One-China Policy posed a constraint.
The essay also recommended investment in advanced missile systems, naval mines and diesel submarines to make Chinese expansion more costly. De Castro cited the Cold War Island Chain Strategy as a precedent for connecting defenses across the region.
The Philippine Information Agency said the country adopted its Comprehensive Archipelagic Defense Concept in 2024, following an announcement by Defense Secretary Gilberto Teodoro Jr. De Castro’s proposed three-way coordination is separate from that Philippine policy.
Japan and the Philippines already cooperate militarily. Japan’s Joint Staff Office said it planned to send about 1,400 personnel to BALIKATAN 26 from April 20 to May 8, including weapons training in the Philippines under the Japan-Philippines Reciprocal Access Agreement.
A U.S. military account said a Japan Ground Self-Defense Force Type-88 Surface-to-Ship Missile struck the decommissioned Philippine Navy ship BRP Quezon on May 6. Taiwan was absent from Japan’s list of exercise participants, and the MAC’s forum notice announced no three-way agreement or timetable.
