Why the Philippines Has Become the Southern Anchor of Taiwan Defense

Nine Access Sites and a Growing Defense Network

Nine Philippine locations are available to U.S. forces under the Enhanced Defense Cooperation Agreement, including several in northern Luzon close to Taiwan. Japan's Reciprocal Access Agreement with Manila is already in force, and Australia and the Philippines expect to finalize another defense agreement in 2026. Together, these arrangements are making the Philippines a southern anchor of planning for a potential Taiwan crisis.

As of October 12, 2025, Manila's growing role rests on geography, military access and preparations for emergencies. Northern Philippine islands overlook the Luzon Strait, the passage between Taiwan and the Philippines that connects waters near China's coast with the Pacific. Forces operating from those islands could help monitor ships, protect sea routes and complicate attempts to isolate Taiwan.

The United States maintains a deep unofficial relationship with Taiwan, while concern about a possible Chinese move against the island extends across the Indo Pacific and into Europe. Many governments want to discourage conflict without making formal commitments to defend Taiwan. Stronger access agreements, exercises and legal arrangements with the Philippines offer a practical way to influence preparations for a crisis farther north.

Manila has its own reasons to cooperate. It is modernizing its armed forces, moving units north and developing ways to defend its coasts and nearby waters. Better airstrips, ports, communications and permissions for visiting forces can support those efforts before any war begins. The same infrastructure would matter if Philippine citizens needed evacuation from Taiwan or shipping routes were disrupted.

The result is a defense network that connects Philippine concerns in the South China Sea with preparations around the Bashi Channel. Manila's partners increasingly see those waters as parts of the same strategic problem: keeping the western Pacific accessible while making military coercion more costly.

The Strait That Connects Two Security Crises

Taiwan occupies the middle of the first island chain, the arc of islands running from Japan through Taiwan to the Philippines. The Luzon Strait is the main southern exit from China's coast into the Pacific. Within it, the Bashi Channel is a critical passage whose deep waters suit submarine operations.

Chinese ships and submarines could seek to pass through Bashi during a Taiwan conflict. Allied forces would try to monitor that movement and, if necessary, restrict it. A blockade of Taiwan would require a sustained naval and air presence, while submarines moving from the South China Sea into the Philippine Sea would depend on the channel's depth and concealment.

Mavulis, the Philippines' northernmost island, lies a short distance from Taiwan's Orchid Island and overlooks the channel. A Philippine Navy detachment was established there in 2023. A forward operating site equipped with sensors, communications and dependable supplies could improve maritime domain awareness, meaning the ability to understand which vessels are moving through nearby waters and what they are doing.

Connecting those sensors with allied systems could make movements through Bashi easier to detect. Mavulis would then contribute to a wider monitoring network, rather than operate as an isolated outpost. Keeping that network supplied and functioning during disruption is part of the military challenge.

Japan depends heavily on cargo passing through the Taiwan Strait, and the Luzon Strait provides an alternative when shipping routes change. Chinese control of Taiwan would leave the Philippines facing waters dominated by China to both its north and west, increasing pressure on Manila's trade and freedom to move. Whether the Luzon Strait remains open would therefore affect military operations and everyday commerce.

Agreements Turn Geography Into Access

The U.S. Philippines Enhanced Defense Cooperation Agreement, known as EDCA, provides rotational access to nine locations. It allows equipment to be positioned in advance, facilities to be built quickly and training to take place frequently. U.S. forces rotate through Philippine locations rather than occupy permanent American bases.

Australia's planned agreement with Manila would make regular defense consultations routine, expand exercises and support Australian investment in Philippine defense infrastructure. Exercise Alon has already brought more Australian forces onto Philippine territory for advanced combined training. The agreement expected in 2026 would give that cooperation a more regular framework.

Japan's Reciprocal Access Agreement allows Japanese and Philippine forces to train and operate on each other's territory. It also supports defense industry cooperation and technology exchanges. These legal permissions help turn a favorable position on the map into locations where partners can actually deploy, train and support their forces.

Manila's widening network also includes arrangements involving Canada, New Zealand, France, South Korea, the United Kingdom, Italy, Ukraine, Germany and Lithuania. Lithuania's defense minister has spoken openly about Chinese pressure on Taiwan and the Philippines, illustrating how concern has spread beyond Asia.

Further arrangements with European and Indo Pacific partners are under discussion. Manila is also weighing agreements with European countries and the United Kingdom that would allow more military visits and training. Each arrangement can give participating forces more options for exercises and a quicker response when tensions rise.

Several dates show how these preparations have developed:

• 2023: A Philippine Navy detachment was established on Mavulis, overlooking the Bashi Channel.
• Early 2024: The United States demonstrated its Typhon mobile missile system in Luzon during Exercise Salaknib.
• By October 12, 2025: Japan's Reciprocal Access Agreement with the Philippines was in force, and Taiwanese officers had observed that year's Balikatan exercises.
• 2026: Australia and the Philippines expect to finalize their new defense agreement.

Missile Exercises Change the Military Calculation

The Typhon system demonstrated during Salaknib in early 2024 can launch Tomahawk and SM 6 missiles. It is based on land and can move by road. Its presence in Luzon showed that targets at sea and on land, including distant ones, could be threatened from Philippine territory during a crisis.

Marine forces have also practiced moving Naval Strike Missile systems to the Luzon Strait during Balikatan. The exercise has become a large venue for training among the Philippines, the United States and Japan, with Japanese forces joining key phases. These drills rehearse the movement and use of coastal defense capabilities where they could affect access to the strait.

U.S. Agile Combat Employment follows a related principle. Instead of concentrating aircraft and their support at a few large bases, forces disperse across smaller airfields. Access to Philippine locations fits that approach, requiring Chinese planners to consider more possible operating sites.

Northern island airstrip and port improvements support both dispersed air operations and coastal defense training. Combined exercises also rehearse sea control, meaning the ability to use an area of water while limiting an opponent's movements there. Legal permissions for rapid deployments help partners use those facilities when needed.

Manila's Taiwan Preparations Remain Unofficial

The Philippines observes the One China policy, even as unofficial coordination with Taiwan has expanded. Senior security officials from both sides have met out of uniform, and Taiwanese officers observed the 2025 Balikatan drills involving U.S., Philippine and Japanese forces.

President Ferdinand Marcos Jr. has said the Philippines would inevitably become involved in a conflict across the Taiwan Strait because of its proximity. Manila's defense treaty with the United States and the U.S. Taiwan Relations Act also shape expectations about how assistance might be requested and delivered.

Philippine preparations include improved airstrips and seaports in the northern islands, along with exercise scenarios for evacuating Philippine citizens from Taiwan. Those measures connect security planning with the needs of people who could be caught in a conflict.

The military has relocated a veteran marine brigade to Ilocos Norte and positioned marine units within reach of the strait. Training now includes ambush tactics, preventing enemy landings, dispersing into caves and quickly obstructing an opponent's movement using civilian trucks adapted for military purposes. Reservists are being brought into coastal defense.

Banners at Camp Cape Bojeador carry a promise linked to the latitude of the country's northern territories: none shall cross the 18th parallel unscathed. The message reflects a posture that treats the north as a forward defensive line. Nearby Japanese and U.S. exercises share that geographical focus.

Renato Cruz De Castro, a professor of international relations at De La Salle University, described the possibility Philippine planners may be considering:

I'm assuming that in a Taiwan contingency scenario the Armed Forces of the Philippines are looking at the possibility of a Chinese attack on Northern Luzon.

His assessment helps explain the combination of stronger northern defenses and agreements allowing allied forces to train there more often. Preparing for a possible threat to Philippine territory also increases the potential costs of Chinese operations across the Bashi Channel.

A Porcupine Defense Built Around Many Small Threats

Manila's modernization approach favors a porcupine defense rather than a race to acquire large warships. The idea is to make an attack painful through smaller, less expensive and widely dispersed systems. A larger navy would have to account for threats from many directions instead of disabling a handful of major platforms.

Maritime autonomous systems are central to that approach. Uncrewed surface vessels and small drones can scout, pass targeting information, work in swarms and carry weapons. Distributed across an archipelago, they can extend surveillance without putting the entire network at risk through the loss of one vessel or installation.

A traditional kill chain moves through a sequence: detect a target, make a decision and strike. Breaking one link can interrupt the process. A kill web connects many sensors, decision points and weapons, allowing information and action to travel through several routes. Losing one platform leaves other parts of the network able to operate.

The mesh fleet concept applies that connected approach to groups of vessels. MARTAC's MANTAS and Devil Ray families of uncrewed boats can deploy from beaches and small harbors and operate together. Systems intended to be expendable, such as the M18 Muskie, can be sent on missions from which they will not return.

Crewed and uncrewed platforms working together can create threats at multiple points. The Philippines has also received India's BrahMos supersonic missiles and trained alongside U.S. units operating Naval Strike Missiles in the strait. Coastal radar and better maritime awareness help those weapons find and respond to potential targets.

A program to acquire mesh fleet platforms and sensors over three to five years is more attainable than a warship acquisition effort lasting decades. The United States and other partners are investing in infrastructure and training to help Philippine forces develop capabilities more quickly.

Relatively cheap, persistent and expendable uncrewed vessels could make suppression expensive for an opponent. Combined with dispersed marines, mobile coastal missiles and rapid supply movements, they could create a broad denial problem across the Luzon Strait and the approaches to northern Luzon. Denial means making an opponent's intended operation too difficult or costly to carry out.

Preparing for Pressure on the Northern Flank

China's gray zone tactics press maritime claims through actions below the level of open warfare, including close approaches by coast guard ships and swarms of fishing vessels. In a Taiwan crisis, Chinese planners might also try to intimidate or strike important Philippine locations before those locations could threaten their operations.

The concern includes an attempt to secure the southern side of a Taiwan operation by neutralizing potential threats in northern Luzon. The historical comparison is Japan's attacks on U.S. positions in the early days of the Pacific War. Philippine and allied preparations anticipate the possibility that a conflict could reach beyond Taiwan itself.

Fixed defenses on key islands, large stores of ammunition and reinforced positions are receiving attention from Tokyo to Manila. Undersea sensors, submarines, uncrewed underwater vehicles, missiles designed to attack ships and mines could work together to slow naval movement through narrow passages.

Ground forces holding critical locations would allow more mobile units to respond elsewhere. For the Philippines, forward sites in Batanes and northern Luzon, bases for fast boats and mobile coastal missiles form parts of a dispersed defense. An opponent would have to locate and suppress multiple positions while accounting for units that can move.

These preparations bring geography, sensors and weapons together. Monitoring the channel helps identify movements; protected positions sustain operations; mobile forces create uncertainty about where a response will come from. The intended effect is to make any operation against the Philippines or through nearby waters more difficult to plan.

Deterrence Also Requires Restraint

Recent confrontations in the West Philippine Sea have included collisions and water cannon blasts. Manila's leaders have sought to maintain their position at sea while keeping diplomatic channels open. Stronger defenses therefore sit alongside efforts to manage incidents before they grow into a wider confrontation.

Some strategists favor U.S. support focused on Philippine coast guard and naval capacity, a measured pace of access site expansion and Philippine leadership around disputed features. That approach seeks better defense and crisis management while limiting a cycle in which each military move prompts another response.

Former national security adviser Hermogenes Esperon Jr. has argued that public trust and a careful effort to mobilize society belong within security planning. He expressed the broader responsibility this way:

Security should not live solely in the domain of generals or diplomats. It must be embedded in the fabric of our societies.

National Security Adviser Eduardo Año has warned that China's challenge also reaches cyberspace and domestic vulnerabilities. He called for a coordinated response involving government, allies and the private sector:

Asymmetric threats demand symmetric unity and systematic actions.

Credible denial and assertive restraint are intended to work together. Forces need the ability to respond if coercion crosses a line, while diplomatic communication and controlled responses reduce the risk of a mistaken calculation.

Evacuations and Shipping Routes Affect Ordinary People

Philippine citizens working in Taiwan would need support and potentially evacuation during a conflict. The government has already rehearsed evacuation scenarios in recent exercises. Northern provinces and Batanes could also become an initial refuge for people fleeing the fighting.

Remote communities would need transport, medical support, reliable supplies and infrastructure able to keep working during disruption. Their distance from larger centers creates logistical difficulties even in peacetime. A crisis could place military movements, evacuees and humanitarian needs on the same ports and airstrips.

Shipping companies could reroute vessels away from the Taiwan Strait if tensions rose. Ships might travel south of the Philippines before heading north through wider passages such as the Miyako Strait near Japan. A detour can add roughly a thousand miles to a voyage, increasing costs and stretching supply chains.

Japan, South Korea and the Philippines therefore have economic reasons to keep the straits open and predictable. Military access and surveillance matter to commerce because safe passage determines whether cargo can follow its usual route or must make a longer journey.

The Next Steps Center on Access and Readiness

Australia and the Philippines expect to finalize their defense agreement in 2026; no more precise completion date was given. Japan's agreement is already moving into implementation through training on each country's territory. Activity at EDCA locations is expected to expand, particularly in the north.

Exercises are expected to continue rehearsing Naval Strike Missile deployments and dispersed air operations around the Luzon Strait. Philippine infrastructure work includes Mavulis and other Batanes locations. Further experimentation with uncrewed surface vessels and drone swarms would connect those assets with coastal radar and maritime patrol aircraft.

Manila is also considering additional arrangements with European partners and the United Kingdom. Cyber defense and crisis communications are expected to take a larger place in planning as malware linked to China and intrusions probe for weaknesses.

Philippine leaders aim to present the buildup as defensive and focused on keeping sea lanes open. The central task is to make military pressure harder to apply while preserving diplomatic room to manage crises. Northern defenses, partner access and preparations for civilians are increasingly parts of that same effort.

Key Points

• The Philippines' position south of Taiwan makes northern Luzon and the Bashi Channel central to regional defense planning.
• EDCA gives U.S. forces rotational access to nine Philippine locations, including several near Taiwan.
• Japan's Reciprocal Access Agreement is in force; Australia and the Philippines expect a new defense agreement in 2026.
• A Philippine Navy detachment was established on Mavulis in 2023, strengthening the country's presence overlooking the channel.
• Exercises have featured Typhon and Naval Strike Missile systems, coastal defense and dispersed air operations.
• Unofficial Taiwan coordination includes security exchanges and Taiwanese observers at the 2025 Balikatan drills.
• Philippine modernization combines mobile missiles, dispersed marines, sensors and proposed networks of uncrewed vessels.
• Evacuation planning, possible refugee arrivals, cyber threats and shipping detours make preparations relevant beyond the armed forces.
• Manila is pairing stronger defenses with diplomacy and crisis management to limit escalation.