Abstract

Disputes over sovereignty over the South China Sea (SCS) have been a persistent issue in literature, with increased relevance over the course of 2025 due to the flaring tensions between China and the Philippines. Meanwhile, Vietnam’s own recent island-building in the area has received considerably less attention in part owing to China’s relative ambivalence to the operation. Various approaches have been adopted to explain the difference in China’s reaction, most of which have neglected the agency of the two smaller parties in the dispute. The research paper offers a different perspective by comparing Vietnam’s and the Philippines’ SCS policies and highlighting their impact on China’s perception. These differences stem from each country’s geographical conditions, foreign policy orientation, historical experience with China, and domestic politics. The paper then lays out three areas in which the policies themselves diverge: on overarching strategy, direct resolution, and external engagement. It concludes with an analysis of how China has recognised and accordingly acted to advance its sovereignty claims against two fundamentally different contenders.

Introduction 

Recent developments in the South China Sea (SCS) have highlighted a significant contrast in China’s reactions toward different claimant states. Since 2021, Vietnam has accelerated its construction of new facilities and island building across the features which it occupies in the Spratly Islands (Steinhauser, Brown & Li, 2025; Asia Maritime Transparency Initiative, 2025). Yet, Beijing’s responses have remained relatively restrained when compared to its pushback against the Philippines over the same period. While a lot of literature has focused on explaining China’s motivations and behavior in the SCS, less attention has been paid to Vietnam and the Philippines’ role as sovereign influences on Beijing (Velasco, 2026).

This research paper addresses the question: “Why do Vietnam’s and the Philippines’ sovereignty-asserting activities in the South China Sea lead to different responses from China?” It argues that China reacts differently because Vietnam and the Philippines employ vastly different engagement policies toward China in contested waters, as reflected in (i) how each situates the SCS issue within their broader bilateral relations, (ii) how they handle regular maritime standoffs and clashes, and (iii) the extent to which they choose to internationalize the dispute and align with external partners. 

The article focuses specifically on the period from 2022 to the present, coinciding with President Ferdinand Marcos Jr.’s assumption of office and Manila’s subsequent policy adjustments. After a brief exploration of the drivers of behaviour, the paper will contrast the SCS policies of Vietnam and the Philippines based on the three aforementioned aspects and conclude by linking these differences to China’s reactions to both countries.

Drivers of Vietnam and the Philippines' approaches to China in the South China Sea 

Geographical location

Vietnam and the Philippines are both Southeast Asian states located at the heart of the Indo-Pacific, adjacent to major trade routes and positioned along China’s southern and southeastern periphery, respectively. Despite these similarities, their territorial characteristics differ markedly. Vietnam’s territory is long and narrow in shape, stretching approximately 1,650 kilometers from north to south, leaving the country with limited strategic depth on land and heightened vulnerability to maritime-based threats (Dang & Nguyen, 2022; Vu, 2022, p.177). However, geographic proximity to China on land, combined with historical experiences of border disputes with inland neighboring states, has reinforced Vietnam’s tendency to prioritize land-based threats in its strategic thinking and military planning (Hoang, 2024, 6-8). By contrast, the Philippines is an archipelagic state with no land borders, leaving the country intrinsically tied to control over its surrounding maritime space. With its northernmost territory less than 90 miles from Taiwan and forming part of the First Island Chain, Manila is highly exposed to intense great-power competition. This makes any expansion of Chinese influence a direct threat to its territorial integrity (Ingram, 2024; De Castro, 2024).

Shared history and ties with China

Due to disparities in power and resources, both Vietnam-China and Philippines-China relations have historically been asymmetric, with China as the dominant actor and a persistent source of concern for the weaker sides (Thayer, 2011; Yamazaki & Osawa, 2021). Vietnam’s relation with China has been particularly complex and turbulent, marked by repeated struggles to defend its independence against Chinese territorial encroachment, most notably China’s seizure of the Paracel Islands in 1974, the Sino-Vietnamese border war in 1979, and the Chinese invasion of territories occupied by Vietnam in the Spratly Islands in 1988. Yet, Vietnam still has a similar model of governance to China and draws heavily on Chinese political culture, institutions, and ideological frameworks (Hoang, 2024, p. 3-4). By contrast, the Philippines’ historical ties with China were primarily commercial and migratory, but were disrupted during Spanish and American colonial rule (Dagdag, 2009, p. 31-59). During the Cold War period, Manila adopted strong anti-communist and anti-China policies, viewing the rise of Communist China in 1949 as a major security threat. The outcome was the 1951 Mutual Defense Treaty with the United States, allowing the Philippines to host US military bases to contain China.

Internal political dynamics

Vietnam’s one-party system relies on collective decision-making, with foreign policy formulated through consensus among Party institutions and key ministries. This model produces incremental rather than abrupt adjustments, thus a high degree of policy consistency and caution (International Crisis Group, 2021). Historical animosity with China makes the Vietnamese population particularly sensitive to how leaders handle Beijing, with any perceived weakness or compromise viewed as unacceptable (Nguyen, 2021, p. 31). Meanwhile, the Philippines’ democratic system concentrates foreign policy authority in the presidency, resulting in a more personalized approach, often shifting with leadership changes. The country’s SCS policies reflect the incumbent President’s perceptions of China, and at times are even used to delegitimize predecessors and to appeal to public sentiment (Wu & Velasco, 2022). 

Differences between Vietnam’s and the Philippines’ engagement policies toward China

On Overarching Strategy: Confinement vs. Fixation

Although both Vietnam and the Philippines seek to maintain the territorial status quo and protect their waters for normal economic activities, the two countries differ markedly in how they position the SCS disputes within their broader relations with China. Vietnam has consistently pursued a strategy of confining maritime disputes, preventing them from spilling over into its overall bilateral relationship with Beijing. On the other hand, the SCS dispute tends to dominate and shape the Philippines’ China strategy.

Vietnam seeks to compartmentalize maritime disputes from its comprehensive strategic partnership with China, prioritizing the resolution of less contentious issues first to lay a foundation of trust, as codified in the 2011 Agreement on basic principles guiding the settlement of sea-related issues. From 2022 to 2025, three bilateral visits by the highest leaders of the two countries took place, strengthening political trust. In December 2023, the two sides announced the building of the Vietnam-China Community of Shared Future. Bilateral discussions focused mainly on cooperation in trade, the digital economy, clean energy, and infrastructure investment, while only symbolic commitments to resolving maritime disputes through peaceful means were mentioned (Ngo, 2025).

For the Philippines, bilateral relations with China are largely assessed through developments in the SCS. In contrast to his predecessor, President Ferdinand Marcos Jr. has regarded the 2016 arbitral ruling as a firm legal foundation for the Philippines’ claims and has signaled readiness to confront China’s aggression over the SCS in the Shangri-La Forum 2024 (Deutsche Welle, 2024). Although President Marcos Jr. held two important meetings with President Xi Jinping in 2023 and concluded a series of economic and infrastructure agreements (China Briefing News, 2024), relations remain overshadowed by recurring maritime disputes and parallel efforts by both sides to legalize their actions in the SCS, notably the Philippine Maritime Zones Act and the Philippine Archipelagic Sea Lanes Act of 2024, as well as China’s 2024 amendments to its Coast Guard Law (Xiaobo, 2024; Inoc & Rodriguez, 2025, p. 68; Yeung & Hui, 2024).

On Direct Resolution: Settlement vs. Confrontation

In handling maritime incidents with China, Vietnam’s restraint and quiet diplomacy differ from the Philippines’ publicised and confrontational responses.

Since the 2019 Vanguard Bank standoff, Vietnam has increasingly exercised restraint in managing maritime incidents with China to avoid escalation and maintain decorum. Instead of publicly criticising China’s actions, Vietnam attempts to resolve any arising issues on the sea bilaterally with China through closed-door negotiations and existing mechanisms (Grossman, 2024; Siow, 2024). This approach manifests in Vietnam’s response to the most serious incident in 2024, when ten Vietnamese fishermen were beaten by Chinese maritime law enforcement officers near the Paracel Islands. Hanoi handled the case through diplomatic channels, issuing formal protests and demands, while refraining from legal action, on-the-ground escalation, or calls for international intervention (VnExpress, 2024). Meanwhile, such incidents were widely reported in domestic media channels to stoke up nationalism against China (Do, 2024; Truc, 2024).

The Philippines’ more escalatory policy toward China in the SCS has meanwhile fueled tensions between the two countries on Second Thomas Shoal and Scarborough Shoal (Al Jazeera, 2024). The China-Philippines Bilateral Consultation Mechanism, originally intended to build trust and promote maritime cooperation, has failed to deliver tangible outcomes (Fook, 2024). Manila has complemented its physical readiness to directly confront China’s coast guard with a transparency initiative that publicly exposes Chinese aggression on domestic and international media. It regularly releases visual evidence of Chinese coercive acts, brings journalists on resupply missions, and conducts community engagements to sustain transparency (Ibarra & Arugay, 2024). The Philippines thereby seeks to impose reputational costs on Beijing, mobilise international pressure and deter interference with its security and economic activities in claimed waters (Rabena, 2024). Moreover, this approach has enabled the Filipino government to shape the information environment, counter cognitive warfare tactics from China and rally strong internal support for a more assertive maritime policy (Fabe, 2024). Through the “transparency initiative,” the SCS dispute is pushed to the forefront of bilateral relations with China, making it more difficult to compartmentalise and manage other areas of cooperation. 

On External Engagement: Caution vs. Coalition

Although Vietnam and the Philippines, like other ASEAN claimant states, both seek to internationalise the SCS disputes to encourage China to resolve them peacefully and in accordance with international law as well as ensure open sea lanes, their degrees and modes of external engagement differ markedly. 

Vietnam adopts a cautious and selective approach in engaging with external powers in the SCS security, aiming to avoid the perception of encirclement or coalition-building against China. Vietnam’s “four nos” defense policy has waved away any external powers’ interference in its SCS strategy and precluded official military cooperation or alliance-building aimed at countering China’s actions (Vu, 2025). In practice, Vietnam engages only in limited maritime defence cooperation with external partners, focusing primarily on capacity-building for coast guard forces, with joint exercises typically being conducted outside disputed waters to avoid provoking tensions (Budiman, 2023; Royandoyan, 2024; Ninh Co, 2025). Hanoi supports the US and other powers in their freedom of navigation operations, as long as their actions are non-aggressive and contribute to regional peace. In 2023, Vietnam welcomed the third visit of a US aircraft carrier in Da Nang while emphasising the parties’ common goal of maintaining peace in the SCS (Pham & Murray, 2023). Vietnamese ports are also a routine stopover of French naval vessels undertaking their missions in the SCS (EEAS, 2024; Lan Chi, 2025).

On the other hand, the Philippines has increasingly embraced a coalition-based strategy that leverages its formal alliance with the US, bilateral defence cooperation with states that share the same maritime concerns, and minilateral security arrangements. It aims to strengthen its deterrence posture and thereby offset the drastic asymmetries in capabilities against China. Under President Marcos, Manila has revitalised and deepened its alliance with Washington, granting enhanced access to military bases under the Enhanced Defense Cooperation Agreement (EDCA), intensifying joint exercises and improving operational coordination (Castro, 2024). During the same period, Manila expanded its defence partnership network by signing a Status of Visiting Forces Agreement with Japan, followed by New Zealand and Canada, while also deepening defence cooperation with Germany and India (Sato, 2025; Wong, 2025). Beyond multilateral maritime drills with the US and its allies, the Philippines is also part of the informal “Squad” grouping, which seeks to strengthen maritime security coordination and deterrence in the Asia Pacific region, and has recently moved toward greater institutionalisation (Beltran, 2025).

China’s perception and reactions in its South China Sea policy 

China’s responses in the SCS are intimately tied to the different approaches adopted by Vietnam and the Philippines across three key dimensions. First, on overall strategy, Vietnam’s shelving of maritime disputes has enabled it to preserve a comprehensive cooperative relationship with Beijing, benefit from deepening economic ties and minimise the risk of political rupture (Tran, 2025). In contrast, China has repeatedly warned that the Philippines’ actions risk undermining the broader relationship. In September 2024, Beijing described China-Philippines ties as being “at a crossroads” and urged Manila to “seriously consider the future” of bilateral relations (Al Jazeera, 2024). While trade and investment have not yet been substantially affected, analysts remain concerned about the potential for China to impose trade or tourism restrictions on the island nation, as it did following the 2012 Scarborough Shoal standoff (Siqi & Jennings, 2023).

Although neither Vietnam’s low-profile diplomacy nor the Philippines’ confrontational approach and “transparency initiative” has succeeded in deterring Chinese activities, Manila’s strategy has escalated tensions by provoking stronger on-the-ground reactions from Beijing and intensifying legal and information warfare. Maintaining a positive international image is key to Beijing’s aspiration to be recognised as a peaceful, responsible and respected major power. Consequently, public criticism is perceived as harmful to China’s international standing (Wei, 2025). From this perspective, the Philippines’ recent actions as part of the “transparency initiative” are viewed in Beijing as a direct challenge to China’s carefully constructed narrative of a peaceful, stable SCS under its management (Lei, 2025; Duo, 2025).

Third, China’s threat perception is shaped by the external involvement of the US and its allies. Beijing is convinced that Vietnam will not either allow major powers to use its territory or build alliances to contain Chinese influence, given Hanoi’s long-standing non-alignment policy. As a result, China views Vietnam’s actions as autonomous rather than US-driven (Vu, 2024). Moreover, China perceives Vietnam’s cautious approach as consistent with its preference for bilateral dispute management, reinforcing Beijing’s view of Hanoi as a manageable and less threatening opponent in the maritime domain. In contrast, Beijing interprets Manila’s actions not as independent choices but as instigated by the US in its Pivot to Asia strategy. China perceives the Philippines’ expansion of US access to military bases under the EDCA as obstructing Chinese operations along the First Island Chain and as part of Washington’s broader strategy to contain China and support Taiwan (Strangio, 2023). According to Robert Ross (2025), China’s pressure on the Philippines is not driven solely by sovereignty disputes but is primarily aimed at pursuing a “wedge strategy” to weaken the US-Philippines alliance. By creating fears of entrapment, Beijing seeks to signal to Washington that supporting Manila could drag the US into an unwanted armed conflict with China, while simultaneously warning the Philippines that US backing is unreliable and insufficient to deter China.

Conclusion

This article delved into Vietnam and the Philippines – as the two Southeast Asian claimants with the most extensive overlapping claims and the most persistent tensions with China in the SCS – and their markedly different engagement strategies. It provides an explanation for the divergence in China’s reactions to the actions of both countries, beyond the substance of sovereignty claims alone. Vietnam’s strategy of compartmentalisation, restraint and non-alignment reassures Beijing and limits threat perception, while the Philippines’ confrontational posture, assertive diplomacy and coalition-building elevate disputes with China into the realm of great-power competition. These findings contribute to broader debates on the diversity of small states’ foreign policy strategies toward major powers, particularly in conflict-prone regions and in the management of territorial disputes. The analysis also points to the value of applying comparative politics methods to understanding conflict management and resolution in the Asia-Pacific.