Expansion of defense agreement reinforces the U.S.-Philippine alliance

Global Watch | 2026-04-26

The expansion of sites under the Enhanced Defense Cooperation Agreement (EDCA) is no longer a technical update to an old alliance framework -- it is becoming the hard edge of a revived U.S.-Philippine security partnership.

In practical terms, the EDCA is building a network of access, logistics and infrastructure that can shorten response times, improve coordination and make deterrence more credible.

That matters because the pressure facing the Philippines in the South China Sea is no longer occasional, with recent reporting also highlighting covert campaigns to destabilize the Philippines.

It is sustained, coercive and tied to a broader contest over military access, political resolve and regional order, one in which Manila is also building a wider web of defense agreements.

In that environment, geography matters. Infrastructure matters. And the ability to move first can matter as much as the ability to strike.

Geography shapes deterrence

EDCA's value lies in what it does to time and distance. The arrangement gives U.S. forces rotational access to agreed Philippine locations while allowing construction, logistics support and the pre-positioning of equipment.

That does not guarantee intervention in a crisis. It does, however, reduce the friction that often determines whether treaty commitments can be translated into real operational choices.

This is why the expansion from five EDCA sites to nine was strategically important.

The additional locations in northern Luzon and Palawan place more alliance infrastructure closer to the Philippines' most sensitive maritime approaches and to the wider fault lines of regional instability, including areas already tied to concerns over U.S. defenses in the Philippines and Chinese countermeasures.

Their importance is not limited to combat scenarios. They improve options for surveillance, sustainment, humanitarian response and force dispersal. In a contested theatre, those functions are part of what makes a defense posture resilient under pressure.

The logic behind EDCA is also practical. It is designed not simply to host U.S. activity, but to help close Philippine capability gaps while supporting longer-term defense modernization.

Gregory Poling of the Center for Strategic and International Studies (CSIS) has argued that this dual purpose is central to the agreement. It gives the armed forces of the Philippines a path to build resilience over time while giving Washington the access it needs to make alliance commitments more credible in the near term.

Philippine officials have framed it carefully. President Ferdinand Marcos Jr. has repeatedly said the sites are not intended for offensive action, but for the defense of the Philippines.

That distinction matters domestically, where sovereignty remains politically sensitive. It also sharpens the external message: these are Philippine bases, under Philippine ownership, being used to strengthen deterrence rather than dilute sovereignty.

Credibility needs capacity

The test now is implementation. This week, Philippine Secretary of National Defense Gilberto Teodoro said U.S. use of some EDCA sites remains limited because of unresolved land and tenure issues.

That is more than an administrative delay. Deterrence depends on whether sites can actually support runway operations, fuel storage, communications, maintenance and rapid access in a crisis.

In other words, strategic value on paper is not enough. If the sites are supposed to shorten response times and sustain joint operations, delays carry strategic costs.

Even so, the broader trend is clear. Washington and Manila have steadily folded EDCA into a wider pattern of defense cooperation that includes updated bilateral guidelines, larger Balikatan exercises and tighter maritime coordination.

Together, those efforts are giving the alliance more operational depth and shifting it from declaratory politics toward practical readiness.

U.S. officials continue to describe the treaty commitment as "ironclad." On their own, such phrases can sound routine. But infrastructure is what gives them meaning. Without access, logistics and prepared facilities, alliance credibility is harder to demonstrate and sustain.

The point is not that EDCA makes conflict inevitable, or that it guarantees a U.S. response in every scenario. It is that the sites make the alliance more usable, more visible and therefore more credible.

In the South China Sea, credibility is a form of capability. The side that can move faster, sustain presence longer and coordinate under pressure holds the stronger hand. EDCA is increasingly designed to ensure that the Philippines does not face that contest alone.