The Philippines announced its new “Comprehensive Archipelagic Defense Concept” (CADC) strategy in January 2024. By extending the reach of the Philippine Army across the country’s Exclusive Economic Zone (EEZ) and expanding strategic depth, the strategy signals a shift toward protecting sovereignty against external threats.
The fuel for this defense shift lies in Manila’s growing tensions with Beijing. China has steadily expanded its actions in the South China Sea, where disputes over the Second Thomas Shoal in the Spratly Islands have become flashpoints.
Within the Philippines’ EEZ, Chinese coast guard vessels have increasingly used aggressive tactics against Philippine missions, turning the South China Sea into a theater of regular confrontation.
The Philippines is not alone in this. Taiwan also faces intensifying Chinese incursions into its air defense zone and maritime space. Both Manila and Taipei now live with the reality of Beijing’s growing coercion, underscoring that their security challenges are interconnected.
Philippine President Ferdinand Marcos Jr. recently acknowledged this situation, declaring that Manila would inevitably be drawn into a Taiwan conflict given its geographic proximity and the large Filipino community on the island. The two governments also share a place in the First Island Chain, Washington’s long-standing maritime containment line to deter Chinese expansion.
Any Taiwan contingency would reverberate immediately across Philippine waters, especially in the Luzon Strait and Batanes Islands. Recognizing this shared vulnerability, Manila and Taipei would both benefit from closer security cooperation — an approach that would also reinforce the credibility and effectiveness of the Philippines’ CADC.
Why Taiwan matters
Geography makes the linkage unavoidable. Mavulis Island is closer to Taiwan than the Philippines. Any blockade or invasion of Taiwan would unfold inside Philippine air and sea space.
Alliances reinforce the connection. Under the Enhanced Defense Cooperation Agreement, US forces could potentially rely heavily on Philippine bases to support operations in a Taiwan crisis, as noted by Marcos. The Mutual Defense Treaty of 1951 also creates legal obligations: if US forces are engaged, the Philippines would almost certainly be drawn in.
In addition, by adopting a firmer stance toward China, and as long as the US maintains its commitment to Taiwan, Manila can leverage that alignment to secure continued US backing in the West Philippine Sea and support for the Philippine Army’s modernization.
This alignment also opens the door to deeper cooperation with US forces in the north, from access to additional bases and joint drills to advanced systems like the Typhon missile, enhancing deterrence across both the South China Sea and the Taiwan Strait.
By framing the CADC as a link in a broader chain of island defense extending from Japan, through Taiwan, down to the Philippines, Manila would strengthen deterrence and complicate Chinese planning.
Manila is not abandoning its “one China” policy by doing so –– rather, it is simply acknowledging that its own security cannot be separated from Taiwan’s stability.
Events in the Taiwan Strait will inevitably shape the Philippines’ security. Success in Taiwan could give Beijing the confidence to advance its South China Sea claims more assertively.
Signs of cooperation
Taiwan has therefore become a more relevant factor in Manila’s defense planning. CADC envisions Philippine Army deployments not only in the West Philippine Sea but also in the Luzon Strait, where any crisis across the Taiwan Strait would quickly affect Philippine security.
The decision to host US Typhon missile systems in northern Luzon, build a coast guard station facing the Bashi Channel, and join Washington and Tokyo in a trilateral summit that emphasized cross-strait stability all reflect this growing awareness.
Some cooperation is already visible. The Philippine Coast Guard has carried out joint patrols with Taiwan in the Bashi Channel, and Taiwanese Navy and Marine officers have taken part as observers in the Kamandag exercise led by US and Philippine forces.
Military steps have been accompanied by closer political engagement. In April, Manila relaxed travel restrictions for Taiwanese officials, allowing easier visits in both directions. Since July, Taiwanese have also been able to enter the Philippines without a visa.
Not surprisingly, Beijing has protested each of these steps.Yet, these growing military and political exchanges demonstrate the greater importance that Taipei now holds for Manila.
The road ahead
The CADC highlights the need for greater intelligence sharing and closer coordination with allies such as the US, Japan, and Australia. Extending that logic to Taiwan is both practical and necessary. Manila does not need to formally recognize Taipei, but it will struggle to realistically defend its northern waters without including Taiwan in its strategy.
Recent reporting shows this trajectory is already underway. As The Japan Times notes, the Marcos administration has begun to draw Taiwan into its wider security architecture through quiet but concrete steps. This suggests that bilateral military cooperation could continue to expand during Marcos’ presidency.
However, larger engagement between Manila and Taipei remains conditioned by restrictions, notably regarding military issues, and China’s leverage has yet to diminish.
Nonetheless, Taiwan should build on this momentum, seeking to enhance its ties with the Philippines. Deepening economic relations and reinforcing cultural exchanges can foster progress.
Ultimately, Manila and Taipei face the same source of pressure and share a similar security environment. By embedding Taiwan within CADC strategy, the Philippines not only strengthens its own defenses but also reinforces the credibility of the First Island Chain as a whole. This complicates Beijing’s calculus and raises the cost of aggression on two fronts.
Without Taiwan, the CADC is incomplete –– with it, Manila reinforces the depth and deterrence needed to face China with confidence.
