Key Takeaways:
- On Tô Lâm’s May 31–June 1, 2026 Manila visit, the Philippines and Vietnam upgraded to an Enhanced Strategic Partnership at 50 years of ties—Marcos’s only Southeast Asian “strategic partner,” sitting opposite each other on the South China Sea and still overlapping as claimants.
- Manila frames it as one tile in a “latticework” with the U.S. alliance plus Japan (now Comprehensive Strategic), Australia, ROK, and India: UNCLOS, the 2016 award, coast-guard hotlines, and incident-prevention MoUs rather than identical claims.
- The piece says ASEAN centrality is strengthened, not undercut, by capable bilateral maritime work; the test is whether dialogue, MDA, port visits, and training actually happen amid uncertain U.S. attention.
The Philippines and Viet Nam have entered a new phase in their bilateral relationship. During Vietnamese President Tô Lâm’s visit to Manila from 31 May to 1 June 2026, the two countries elevated their relationship from a Strategic Partnership to an “Enhanced Strategic Partnership.” The upgrade came as the Philippines and Viet Nam marked the 50th anniversary of the establishment of diplomatic relations.
The elevation is more than a ceremonial milestone. It reflects the growing convergence of Philippine and Vietnamese interests in a region facing increasing geopolitical uncertainty, particularly in the South China Sea. It also illustrates a broader direction in Philippine foreign policy: the effort to build a network of capable and trusted partners that can reinforce regional stability without replacing the country’s longstanding alliance with the United States.
President Ferdinand R. Marcos Jr. captured the significance of the relationship when he described Viet Nam as the Philippines’ “sole Strategic Partner” in Southeast Asia. Geography is one reason for this distinction. The Philippines and Viet Nam sit on opposite sides of the South China Sea, placing both countries at the center of one of the region’s most important strategic waterways. Their security and prosperity are therefore closely connected to the stability of the maritime order.
But geography alone does not explain the deepening relationship. The Philippines and Viet Nam are both ASEAN member states, both South China Sea claimant states, and both have a strong interest in preserving an open and rules-based regional order. At the same time, their maritime claims overlap. The significance of their relationship lies partly in their ability to manage these differences while expanding cooperation in areas where their interests converge.
Manila’s emerging network of strategic partnerships
The Philippines’ growing relationship with Viet Nam should be viewed within the broader evolution of Philippine foreign policy.
Strategic partnerships are not new to Manila. The Philippines established a Strategic Partnership with Japan in 2009, while the Aquino administration established Strategic Partnerships with Viet Nam in 2015. It also forged a Comprehensive Partnership with Australia in the same year. Under the Marcos Jr. administration, Australia’s relationship with the Philippines was elevated to a Strategic Partnership in 2023, while strategic partnerships were established with the Republic of Korea and India.
What is different under Marcos is that the administration has begun to articulate more clearly why some countries are considered strategic partners.
Speaking at the Observer Research Foundation during his August 2025 visit to India, Marcos identified four principles that should guide the Philippines in developing strategic partnerships: mutual and strategic trust, common cause, clear alignment of interests, and a demonstrated record of responsible behavior in the international arena and the global commons.
These partnerships, together with the Philippines’ alliance with the United States, form what Marcos has called a “latticework of partnerships.” The concept is important. Manila is not choosing between its traditional alliance with Washington and its relationships with other regional powers. Rather, it is attempting to build several overlapping relationships that can provide additional diplomatic, economic, and security options.
The Philippines’ relationships with Japan and Viet Nam are particularly noteworthy because both have now been given enhanced designations. Japan’s relationship was elevated to a Comprehensive Strategic Partnership in 2026, which Marcos described as the highest tier of the country’s diplomatic framework. Viet Nam’s relationship was elevated to an Enhanced Strategic Partnership.
It could be argued that the Philippines maintains more extensive defense cooperation with Australia, South Korea, and India. Nevertheless, their strategic partnerships with Manila were only formally established within the past three years, whereas the Philippines-Vietnam Strategic Partnership has evolved over more than a decade.
Nevertheless, the important point is that Manila is increasingly seeking partners that can contribute to Philippine security and resilience while sharing an interest in a stable and rules-based Indo-Pacific.
Why Viet Nam matters
The Philippines-Viet Nam Strategic Partnership dates back to 17 November 2015, when President Benigno S. Aquino III and Vietnamese President Trương Tấn Sang agreed to establish the partnership on the sidelines of the APEC Economic Leaders’ Meeting in Manila.
The 2015 Joint Statement already contained many of the principles that continue to underpin the relationship today. Both countries reaffirmed their commitment to regional peace and stability, the peaceful settlement of disputes, freedom of navigation and overflight, and international law, including the 1982 United Nations Convention on the Law of the Sea (UNCLOS).
More than a decade later, these principles remain relevant.
The 2026 Enhanced Strategic Partnership Declaration reaffirmed the importance of UNCLOS and their positions vis-à-vis the 2016 South China Sea Arbitral Award. For Manila, these are not merely legal references. They are central to the preservation of a maritime order in which the rights of coastal and claimant states are determined by international law rather than by the relative power of individual states.
This is where Philippine and Vietnamese interests converge most clearly.
Both countries have maritime claims in the South China Sea, although their claims are not identical. Both also have an interest in ensuring that disputes do not undermine the broader maritime order. Their strategic partnership therefore demonstrates an important feature of regional diplomacy: states do not need to agree on everything to cooperate strategically.
Indeed, the ability of Manila and Hanoi to manage their differences may be one of the most significant aspects of their relationship.
Strengthening the regional rules-based order
The first implication of the enhanced partnership is therefore its contribution to the rules-based regional order.
The Philippines has long relied on international law as an important source of strategic and diplomatic leverage. Viet Nam has likewise emphasized international law, UNCLOS, and peaceful dispute settlement in articulating its position on the South China Sea.
Their cooperation reinforces these shared positions.
This becomes particularly important at a time when uncertainty surrounds the future trajectory of US foreign policy. The second Trump administration has broadly maintained US engagement in the Indo-Pacific, but Washington is simultaneously dealing with competing strategic priorities in Europe, the Middle East, and elsewhere.
For Southeast Asian countries, the issue is not necessarily whether the United States will leave the region. Rather, it is whether the level, consistency, and long-term allocation of American attention and resources can be taken for granted.
For the Philippines, the answer is increasingly clear: it cannot.
This does not mean that Manila should seek to replace its alliance with Washington. The US alliance remains the foundation of Philippine external security policy. But an alliance works better when supported by capable partners and a resilient regional environment.
The Philippines’ strategic partnerships can therefore be understood as additional layers of resilience. They give Manila more diplomatic relationships, more avenues for cooperation, and more opportunities to work with countries that share particular interests.
The relationship with Viet Nam is especially important in this regard because it shows that Southeast Asian states themselves have agency in shaping the regional order. They are not simply objects of competition between Washington and Beijing.
From diplomatic relations to maritime cooperation
The second implication is the growing depth of defense and security cooperation between Manila and Hanoi.
The 2026 declaration identifies defense and security as a central pillar of the bilateral relationship. Both governments agreed to strengthen strategic dialogue, expand information sharing, enhance military education and training, increase exchanges between defense and maritime law enforcement agencies, facilitate more frequent port visits, and deepen cooperation in addressing maritime security challenges.
This represents a significant evolution from the relationship established in 2015.
The two countries have also developed mechanisms designed to manage potential friction. These include the Memorandum of Understanding on Incident Prevention and Management in the South China Sea, the Memorandum of Understanding on Maritime Cooperation, and the hotline communication mechanism between their respective Coast Guards.
Such mechanisms are particularly important because Manila and Hanoi are not merely cooperating partners; they are also claimant states with overlapping maritime interests.
Rather than allowing these differences to define the entire relationship, the two governments have increasingly developed mechanisms to manage them while expanding cooperation in other areas.
This is strategically valuable.
More frequent military and coast guard exchanges can improve familiarity and interoperability. Information sharing can enhance maritime domain awareness. Hotline mechanisms can reduce the risk that an incident at sea escalates into a wider diplomatic dispute. Port visits and military exchanges can build confidence and strengthen institutional relationships.
These initiatives can also contribute to deterrence and regional resilience, particularly as maritime competition in the South China Sea becomes more complex.
Importantly, however, Manila and Hanoi do not need to frame all of this cooperation explicitly in terms of balancing China for it to have strategic consequences. The more closely Southeast Asian states cooperate on maritime security, international law, and crisis management, the greater their collective capacity to protect their interests and maintain a stable regional environment.
Reinforcing ASEAN centrality
The third implication concerns ASEAN.
It may appear paradoxical that two ASEAN member states would deepen a bilateral strategic partnership at a time when ASEAN centrality is repeatedly emphasized. In reality, there is no contradiction.
ASEAN has historically sought to engage all major powers through a dense network of economic, political, diplomatic, and security relationships. Scholars have described this approach as “omni-enmeshment”: the effort to draw major powers into sustained regional engagement rather than allowing regional politics to become dominated by a single external power.
ASEAN’s ability to convene major powers remains one of its principal sources of influence. The East Asia Summit, ASEAN Regional Forum, ASEAN Plus Three, and ASEAN Defence Ministers’ Meeting Plus provide platforms through which Southeast Asian states engage the major powers on political, economic, and security issues.
ASEAN, however, cannot address every regional challenge through multilateral mechanisms alone.
This is where bilateral and sub-regional cooperation becomes important. The Philippines-Viet Nam partnership does not undermine ASEAN centrality. Rather, it can strengthen the capacity of individual ASEAN members to contribute to a more resilient regional order.
The 2026 declaration itself reinforces this point by reaffirming ASEAN unity and centrality and by emphasizing cooperation involving sub-regional mechanisms such as BIMP-EAGA and the Mekong sub-region.
In other words, ASEAN centrality does not require ASEAN member states to limit their bilateral strategic relationships. On the contrary, a stronger ASEAN can emerge from member states that are themselves more capable, more connected, and more resilient.
The real test is implementation
The elevation of the Philippines-Viet Nam relationship to an Enhanced Strategic Partnership is an important milestone in Manila’s evolving foreign policy. It reflects the growing strategic convergence between two ASEAN claimant states that share an interest in international law, maritime stability, and a rules-based regional order.
It also demonstrates the continuity of Philippine foreign policy. The effort to cultivate strategic partnerships did not begin with the Marcos administration. What has changed is the pace at which Manila has expanded these relationships and the administration’s increasingly explicit articulation of how strategic partners are selected.
Viet Nam occupies a particularly important position in this network.
The two countries share geography, common membership in ASEAN, overlapping maritime interests, and a growing convergence of strategic concerns. At the same time, their relationship illustrates that strategic cooperation does not require complete agreement. Manila and Hanoi have been able to manage their maritime differences while expanding cooperation in defense, maritime security, and regional diplomacy.
That may ultimately be the most important lesson of the partnership.
In an increasingly uncertain Indo-Pacific, the Philippines does not have to choose between its alliance with the United States and stronger relationships with other regional partners. Nor do Southeast Asian states have to choose between bilateral cooperation and ASEAN centrality.
The more effective strategy may be to build both.
For Manila, the Philippines-Viet Nam Enhanced Strategic Partnership is therefore best understood not as an end in itself, but as another layer in the country’s emerging diplomatic and security architecture. Its value will depend less on the label attached to the relationship than on what the two governments are able—and willing—to do with it.
