Most coverage of the South China Sea territorial disputes has understandably centered on China’s assertiveness in pressing its territorial claim to the entire body of water. After all, using its notorious “nine-dash line” as justification, China has over the past 15 years undertaken extensive land reclamation projects and militarized the features it occupies in the disputed sea. As a result, less attention has focused on the activities of other claimants, which include Vietnam, the Philippines, Malaysia, Indonesia and Brunei, in addition to Taiwan, whose claims replicate those of Beijing. Of them all, Vietnam has been by far the most proactive in asserting its own sovereignty claims in the South China Sea.
These center on the Paracel Islands—referred to as Hoang Sa in Vietnam—in the northern part of the disputed sea, roughly equidistant from China’s southern island province of Hainan and Vietnam’s central coastline, and the Spratly Islands—referred to as Truong Sa in Vietnam—about 450 miles further south. While China has exercised de-facto control of the Paracel Islands since a brief battle with then-South Vietnam’s naval forces in 1974, Hanoi has focused its efforts on boosting its defenses on features it controls in the Spratly Islands. According to the Asia Maritime Transparency Initiative, or AMTI, the pace of construction has picked up in recent years, to such an extent that Vietnam’s total dredging and landfill in the South China Sea amounts to 2,360 acres—roughly half of China’s total of 4,650 acres. By comparison, four years ago Vietnam’s total was just 329 acres, less than one-tenth of China’s total at the time.
On Hanoi’s largest feature, Barque Canada Reef—known as Bai Thuyen Chai in Vietnam—a new runway is under construction, with reclaimed land meaning it could stretch to just under 2 miles in length. That would potentially make it long enough for larger military transport, surveillance and bomber aircraft to take-off and land. For now, Vietnam’s only runway in the region—located on Spratly Island—is significantly shorter, at just under a mile. Several other Hanoi-occupied features, of which there are 27 in total, could also form ideal sites for new runways after recent and ongoing expansion work, including at Pearson, Ladd and Tennent reefs.
Vietnam’s recent construction, as reported by AMTI, has added to existing pillbox structures built over a longer period of time at other islets and features, as well as boat ramps, coastal fortifications and outward-facing concrete pads connected to bunker formations, indicating Hanoi’s rising capability to defend its maritime outposts from external military threats. It must be noted, however, that Beijing remains by far the most powerful actor in the sea, with garrisons of troops, fighter jets and anti-ship and anti-aircraft missile systems reportedly deployed to its three largest features in the Spratly archipelago—at Fiery Cross, Mischief and Subi reefs.
Vietnam’s rapid building work on features it controls in the South China Sea has arguably prevented China from taking the kinds of aggressive actions reported by the Philippines in recent years.
Hanoi’s actions have been largely driven by Beijing’s militarization of the sea, against a background of historical rivalry between the two countries that endures despite shared ideological ties between their respective ruling communist parties. Vietnam’s rapid building work, cementing the establishment of a permanent presence on its own features, has arguably prevented China from taking the kinds of aggressive actions reported by the Philippine coast guard in recent years near Scarborough and Second Thomas shoals in the southern portion of the sea. Despite Manila’s assertion of sovereignty and its geographical proximity to both, Chinese vessels have allegedly sought to block resupply missions and engaged in dangerous maneuvers targeting Philippine vessels, enflaming tensions and provoking a strong rebuke of Beijing by Manila.
Reactions to Vietnam’s activities by the Philippines and other claimants, however, have been decidedly more muted than their responses to Chinese actions.
A Philippine coast guard spokesperson explained Manila’s differing stances last year, telling reporters that “Vietnam focuses on minding their own affairs. They do not engage in harassing our fishermen or illegally deploying coastguard vessels and maritime militia in the waters surrounding our occupied maritime features.” Since taking office in June 2022, Philippine President Ferdinand Marcos Jr. has taken a firmer line on China than his predecessor, former President Rodrigo Duterte. That has included efforts to intensify maritime cooperation with other claimants, resulting in the first-ever joint coast guard drills with Vietnam last August, in waters west of Luzon. A Vietnamese ship with a crew of 80 docked in Manila for four days amid the exercises, which included the use of water cannon to repel other vessels, a tactic the Chinese coast guard has deployed several times against Philippine ships in the past year.
Malaysia, the other major South China Sea claimant state in the Association of Southeast Asian Nations, or ASEAN, has been more friendly toward China than the Philippines, especially since Prime Minister Anwar Ibrahim’s election in November 2022. Malaysia reportedly sent a letter to Hanoi last October raising concerns over Vietnam’s island-expansion activities and protesting the presence of Vietnamese fishermen in Malaysian waters. Yet the following month, any dent in ties appeared to have been repaired when Anwar hosted Vietnamese Communist Party General-Secretary To Lam in Kuala Lumpur, upgrading bilateral ties to a “comprehensive strategic partnership” and committing to uphold freedom of navigation and overflight in the South China Sea.
The other ASEAN claimant states have generally turned a blind eye toward Vietnam’s land reclamation, as Hanoi’s solidified control over its features denies China total hegemony in the South China Sea. This is a core aim shared by all claimants, despite their ongoing disputes among themselves based on historical rights and overlapping Exclusive Economic Zones.
Vietnam has itself been very quiet when it comes to China’s land reclamation. Given the two countries’ close political ties and the fact that China is also Vietnam’s largest trading partner, Hanoi has no intention of antagonizing Beijing over the maritime dispute. Last year, Vietnam even began conducting quarterly coast guard patrols in the Gulf of Tonkin with its powerful northern neighbor. And in Vietnam’s current political climate, with the ascendant To Lam—considered a hardliner—and other “party-first” traditionalists in control of the Politburo after Vietnam’s recent reshuffle of its top leadership, there is little sign that Hanoi will look to weaken its historically important relationship with China.
This is not to say that tensions at sea may not flare up, a point that is underscored by the history of repeated but short-lived conflicts between the two countries. In 1979, China invaded Vietnam in response to Vietnam’s occupation of Cambodia to topple the Khmer Rouge the previous year; the two sides fought a bloody monthlong war before the Chinese were forced to retreat. The two sides have clashed in disputed waters, too. The Johnson South Reef skirmish in 1988 led to the loss of 64 Vietnamese sailors, while China’s positioning of an oil rig close to the Paracel Islands in May 2014 triggered a maritime stand-off in which both sides’ vessels bumped each other and exchanged water cannon fire over several weeks, sparking rare anti-China street protests in Vietnam.
Despite these past clashes, however, Vietnam has refrained from placing advanced weapons systems on its features in the South China Sea, contrary to earlier reports. Hanoi is resolute in sticking to its “Four No’s” foreign policy, which includes “no military alliances” and “no threat or use of force in international relations.” The absence of hostile Chinese actions toward Vietnam at sea in recent years of the kind seen directed at other claimant states—notably the Philippines—perhaps reflects a reciprocal calculus in this sense. At times, however, Beijing has voiced its opposition to Vietnam’s building work and recently conducted live-fire exercises in the Gulf of Tonkin, following Hanoi’s demarcation of its territorial waters in the area. Hanoi, for its part, has pushed back rhetorically and reaffirmed its sovereignty claim over the Spratlys and Paracels in response to clashes between local Chinese law enforcement vessels and Vietnamese fishermen.
One such incident took place last September, when men armed with iron rods boarded a small Vietnamese fishing boat that had been stopped by two larger steel-hulled “foreign” ships near the Paracel Islands. Up to 10 Vietnamese crew members were reportedly beaten, with three suffering broken limbs, before being ordered via a translator to sail back to the Vietnamese coastline.
Vietnam’s growing defense and security ties with the U.S., viewed as a hedge against China, have served as a guardrail against more serious escalations. Ties with Washington reached new heights in the latter years of former President Barack Obama’s time in office, culminating in 2016, when the U.S. lifted a longstanding ban on providing lethal weapons to Vietnam that dated back to the post-Vietnam War period. President Donald Trump visited Vietnam twice during his first term, while in September 2023, under then-President Joe Biden, Vietnam’s ties with the U.S. were upgraded to a “comprehensive strategic partnership”—matching the level of Hanoi’s ties with Beijing.
It’s no coincidence that a primary focus of Hanoi’s security ties with Washington has been on improving its capacity to police its waters. The U.S. has transferred two refurbished Hamilton-class cutters to Vietnam for use by its coast guard, in 2017 and 2021, having also delivered 18 “metal shark” patrol boats. Aligning with the United States’ aim to ensure freedom of navigation in the South China Sea, Vietnam has also welcomed U.S. Navy ships to its ports with increasing regularity. In 2018, the USS Carl Vinson became the first aircraft carrier to dock in Vietnam since the end of the Vietnam War in the 1970s, followed by the USS Theodore Roosevelt in 2020 and the USS Ronald Reagan in 2024. The flagship vessel in the U.S. Navy’s Japan-based 7th Fleet, the USS Blue Ridge, also made a high-profile port call at Cam Ranh in central Vietnam last July alongside the US Coast Guard cutter Waesche.
Trump’s return to office, however, has brought concerns that Hanoi’s ties with the U.S. might suffer, given his threat of 20 percent across-the-board tariffs and Vietnam’s large trade deficit with Washington, which totals $104 billion—almost three times the $38 billion it amounted to in 2017 at the start of Trump’s first term. It is possible that Vietnam could offset this by purchasing commercial aircraft, liquefied natural gas and more weapons from the U.S., especially as arms supplies from Russia—Vietnam’s traditional ally—have dried up due to Moscow’s need to commit resources to the ongoing war in Ukraine. On the other hand, given Trump’s transactional foreign policy style—including his willingness to deal with authoritarian regimes—and long-held anti-China stance, Vietnam is arguably well placed to benefit from Trump’s return and cement its status as a strategically important mid-sized power in Asia.
That said, Hanoi’s ties with the U.S. are unlikely to expand beyond advancing cooperation in areas of shared strategic interest. As a result, Vietnam will stick to its principle of “bamboo diplomacy,” remaining firmly rooted while not swaying too far in either direction. Maintaining a good relationship with both major powers and avoiding alignment is key if Vietnam is to maintain the autonomy that has enabled it to navigate tensions and expand its foothold in the South China Sea until now.
Michael Hart is a writer and researcher covering conflict and postwar issues in Southeast Asia. He has researched for the International Institute for Strategic Studies (IISS) and Action on Armed Violence (AOAV), and has contributed to publications including World Politics Review, The Diplomat, and Asia Sentinel. He is Editorial and Social Media Coordinator at The Pacific Review journal, based at the University of Warwick.