Vietnam Expands South Reef Beyond 60 Hectares as Spratly Construction Approaches China's Scale

A small reef becomes a substantial Vietnamese outpost

Vietnam has expanded South Reef in the northern Spratly archipelago into a fortified platform of more than 60 hectares in roughly two years, turning a feature once exposed only at low tide into one of its largest positions in the disputed island group. As of October 29, 2025, the construction forms part of a wider campaign that has brought artificial land to all 21 Spratly features held by Vietnam.

South Reef, known in Vietnamese as Da Nam, lies less than five kilometers from Vietnam's Southwest Cay and about eight kilometers from Parola Island, held by the Philippines. It is also roughly 50 kilometers north of Subi Reef, held by China. The expansion is taking place in a cluster of outposts where neighboring forces operate within short distances of each other.

Recent satellite imagery shows dredgers, cranes and support vessels working in rotation, with buildings, roads and protective berms appearing across the new land. Dredgers collect material from the seabed and move it into shallow areas, gradually creating a platform that crews can reinforce and build on.

Vietnam's broader construction drive is approaching the scale of China's earlier reclamation campaign. By March 2025, independent assessments estimated that Vietnam had created about 70 percent as much artificial land in the Spratlys as China. Another analysis put Vietnam's new land since late 2021 at more than 8.5 square kilometers.

The larger footprint gives Hanoi more room for troops, supplies, shelters and surveillance equipment. Its practical value lies in keeping personnel and vessels supplied across scattered outposts, especially when bad weather or political tension makes movement more difficult.

From two pillboxes to more than 60 hectares

Vietnam first occupied South Reef in the late 1980s during what it calls the CQ 88 campaign. For decades, the position consisted of two small pillbox posts usable only at low tide. Pillboxes are compact fortified positions that provide protection for the personnel inside.

Reclamation began in October 2023 and advanced rapidly through 2024 and 2025. The platform now covers more than 60 hectares, equivalent to more than 0.6 square kilometers. Buildings consistent with barracks and logistics facilities have appeared alongside protected storage identified by analysts as ammunition or munitions depots.

South Reef's development also includes facilities for everyday garrison life. Common spaces and recreation rooms have been noted, while troops are encouraged to grow vegetables and keep small livestock to supplement supplies brought from elsewhere.

The construction timeline places South Reef within a campaign that has widened over several years:

• Late 1980s: Vietnam occupied South Reef during the CQ 88 campaign.
• Since 2021: Vietnam expanded its artificial land across the Spratly features it holds.
• October 2023: Dredging began at South Reef.
• 2024 and 2025: South Reef's reclamation and construction accelerated.
• Early 2025: Expansion activity extended to eight additional sites.
• March 2025: Assessments put Vietnam's artificial land area at about 70 percent of China's earlier Spratly reclamation footprint.

Why the northern Spratlys matter

South Reef sits near shipping routes connecting North East Asia with Southeast Asia, Australia and the Pacific. The wider corridor carries about one third of global maritime trade, while the surrounding waters also contain productive fishing grounds.

Southwest Cay, Vietnam's nearby position, has a lighthouse, a garrison, barracks, a common hall and other communal facilities. Philippine held Parola Island remains comparatively less developed. The short distances between them allow forces to observe activity and respond quickly when an incident occurs.

Vietnam can combine a larger South Reef with nearby outposts, harbors and air access elsewhere in its network. In military terms, this improves internal lines of communication: the routes used to move people, equipment and information between positions.

Stronger connections between outposts reduce reliance on every supply movement coming directly from the mainland. They also help Vietnam maintain its presence during tension, when a small isolated post could otherwise run short of essential supplies.

A construction drive across all 21 features

Vietnam has added artificial land to all 21 features it holds in the Spratly Islands since 2021. At the start of 2025, activity spread to eight additional sites, combining work at reefs receiving new dredging with renewed expansion at existing positions.

New dredging and landfill appeared at Alison, Collins, East, Landsdowne and Petley reefs. Fresh rounds of expansion resumed at Amboyna Cay, Grierson Reef and West Reef. South Reef is therefore one part of a construction effort distributed across the archipelago.

The March 2025 estimate of 70 percent of China's artificial land footprint and the separate estimate of more than 8.5 square kilometers added since late 2021 describe the scale from different angles. The first compares Vietnam with China's earlier campaign; the second measures the amount Vietnam has built during its recent push.

Vietnam's expansion is on a trajectory that could match or exceed the area China created during the previous decade. The value of that land, however, also depends on the facilities installed, the vessels and aircraft available to use them, and the ability to keep each position operating.

Harbors, storage and a repeated defensive layout

Vietnamese construction crews are carving harbor basins and laying wharves at multiple reefs. Sheltered basins give vessels places to moor, while wharves make it easier to unload cargo when weather and sea conditions are rough.

New storage sites appear at each reef, often consisting of six containers surrounded by thick blast walls. Those walls provide a protective barrier around material that analysts identify as ammunition or other munitions.

Standardized groups of six buildings are arranged along three sides of a courtyard, facing outward toward the water. Many reefs have two such groups at opposite ends of the new landmass. The repeated arrangement suggests an emphasis on supplies, surveillance and defense at close range.

Vietnam gains practical advantages from using similar layouts across its positions. Standard buildings simplify construction and maintenance, while additional storage, fuel and power make personnel rotations and equipment staging easier.

The pattern points toward a network designed to remain supplied and hold its positions. Larger platforms can accommodate coastal defense weapons, rockets with a short range and improved radar, giving individual outposts more ways to monitor approaching activity and resist pressure.

Barque Canada Reef gets a second Spratly airstrip

Barque Canada Reef stands out within the construction program because Vietnam is building a runway roughly 3.0 to 3.2 kilometers long. It will become the country's second airstrip in the Spratlys, alongside the existing strip on Spratly Island.

A runway of that length can accommodate transport aircraft and maritime patrol planes. The site can also support helicopters, helping with troop rotations, medical evacuation and patrol flights. Air access offers another route for reaching outposts when moving people or supplies by sea is difficult.

Analysts had considered whether other long features, including Ladd, Pearson, Tennent and South Reef, might also receive airstrips. Recent site layouts make full length runways at those positions unlikely because building clusters and storage occupy the longest stretches of reclaimed land.

Barque Canada Reef is therefore likely to host the only new airstrip in the current program. Malaysia has protested the runway construction, adding another claimant's concern to the scrutiny of Vietnam's expansion. No completion date for the runway was given.

Beijing objects while focusing pressure on Manila

China has objected to Vietnam's construction and increased patrols near Vietnamese held features. Its public response has nevertheless been relatively muted compared with its confrontations with the Philippines, and Vietnamese work has proceeded with little direct interference.

At a routine press briefing, Chinese Foreign Ministry spokesperson Guo Jiakun restated Beijing's claim to the Spratlys and its opposition to construction by other claimants:

The Spratly Islands are China's inherent territory. China firmly opposes relevant countries construction activities on illegally occupied islands and reefs. China will take necessary measures to safeguard its territorial sovereignty and maritime rights and interests.

China appears to be balancing the protection of its expansive claims with an effort to avoid a rupture with Hanoi that could draw Vietnam closer to outside partners. Its sharper rhetoric and coercive activity have been directed toward Manila in other parts of the South China Sea.

Collin Koh, a research fellow at the S. Rajaratnam School of International Studies in Singapore, described China's concentration on confrontations with the Philippines:

For now much of China's bandwidth of attention is directed at the Philippines, and it would rather maintain a stable front with each of the other Southeast Asian rivals in the South China Sea.

Ray Powell, who leads the SeaLight maritime transparency project at Stanford University, linked Beijing's restrained response to an effort to keep Manila apart from other claimants:

It seems that Beijing has calculated that keeping the Philippines isolated from the other South China Sea claimants is worth more right now than preventing Vietnam from making substantial territorial gains.

Confrontations between Chinese and Philippine vessels near Second Thomas Shoal and Scarborough Shoal have increased sharply. Incidents have included ramming and the use of water cannon at high pressure that caused injuries. Chinese ships have also sustained damage during tense maneuvers. Those encounters have attracted regional and international attention while construction at Vietnamese positions continues.

Vietnam and the Philippines manage close quarters

Hanoi and Manila have agreed procedures for managing encounters at sea and strengthened coast guard cooperation and information sharing. Those arrangements matter in the northern Spratlys, where personnel stationed on nearby features can observe one another's daily activity.

Vietnamese and Philippine troops on neighboring outposts often maintain cordial personal ties. South Reef's expansion may cause irritation in some circles in Manila, yet both governments have reasons to keep disagreements contained.

Regular communication and agreed procedures help prevent routine interactions from becoming incidents. Geography concentrates activity around South Reef, Southwest Cay and Parola Island, while practical coordination gives the two countries ways to manage that proximity.

Maritime rights follow the natural feature

Vietnam has not formally expanded its maritime claims through this construction. Under the United Nations Convention on the Law of the Sea, South Reef's original status as a low tide elevation governs its maritime entitlements. A low tide elevation is land exposed when the tide is low and covered when the tide rises.

Such a feature has no territorial sea or exclusive economic zone of its own. Its legal status remains tied to its natural condition, even after dredging adds sand and construction places concrete above the water.

The treaty distinguishes between different kinds of natural features. An island able to sustain human habitation or an economic life can generate an exclusive economic zone extending 200 nautical miles. Within that zone, a coastal state has rights over resources. A rock unable to sustain such habitation or economic life generates only a territorial sea extending 12 nautical miles.

Many Spratly features are small and close together, so maritime zones can overlap where legal entitlements exist. A 2016 ruling by an international tribunal in The Hague found no legal basis for expansive claims to historic rights over most of the South China Sea.

Vietnam's work changes the physical space available for its outposts while their maritime entitlements remain governed by the law of the sea. That helps explain the emphasis on consolidation, resupply and maintaining positions rather than announcing new claims.

A stronger network with continuing limits

Vietnam's larger bases offer better logistics, greater endurance at sea and more resilient communications between outposts. Harbor basins and wharves allow supply ships and patrol craft to remain forward for longer periods, closer to the areas where they operate.

Those facilities can support monitoring of fisheries, escorts for survey vessels and responses to harassment affecting oil and gas operations. Improved radar and space for defensive equipment can also raise the cost of coercion around an individual position.

Vietnam's navy and coast guard remain smaller and less modern than China's forces, and fleet expansion has slowed. The broader balance still favors China even as Vietnam makes its own outposts harder to isolate and easier to sustain.

The new runway at Barque Canada Reef will improve medical evacuation and the movement of supplies. Together with standardized buildings, storage and sheltered moorings, it supports a defensive network built to endure in place rather than project power over long distances.

Environmental damage and the cost of staying above water

Dredging and landfill damage coral reefs and seagrass beds, stir sediment into the water and reduce water quality. The construction program is popular domestically as a demonstration of resolve, while warnings about lasting ecological damage and exposure to climate risks accompany the expansion.

Most reclaimed platforms sit barely above sea level. Heavy surf during storm seasons can erode protective berms and flood lower areas. Rising seas and stronger storms will keep pressure on these positions, increasing the cost of maintaining them.

Artificial islands need repeated reinforcement against waves and storm surge. Maintenance can involve adding fresh fill, repairing quay walls and extending breakwaters. Even larger outposts remain vulnerable to extreme weather, making engineering and restraint in their use continuing requirements.

Hanoi has discussed expanding marine protected areas in the East Sea as part of its Marine Strategy to 2030. Such reserves could support fisheries and habitats while providing a framework for patrols and enforcement.

South Reef's roads, seawalls, quay lengths and sheltered moorings will indicate how quickly the new land becomes a fully functioning outpost. Progress on Barque Canada Reef's runway will also affect Vietnam's ability to manage rotations and surveillance across the northern and central Spratlys.

China is likely to continue visible patrols near Vietnamese positions while concentrating its sharper confrontations on the Philippines. Malaysia and the Philippines will watch for developments affecting their own claims. Changes are likely to proceed in increments, often appearing first in commercial satellite imagery before official statements follow.

Key Points

• South Reef has expanded beyond 60 hectares since reclamation began in October 2023.
• Vietnam has added artificial land to all 21 Spratly features it holds, with activity extending to eight additional sites in early 2025.
• By March 2025, assessments put Vietnam's artificial land footprint at about 70 percent of China's earlier reclamation area.
• A separate analysis estimated more than 8.5 square kilometers of new Vietnamese land since late 2021.
• Barque Canada Reef is receiving a runway roughly 3.0 to 3.2 kilometers long, likely the only new airstrip in the current program.
• Harbors, wharves, protected storage and repeated building layouts support supplies, surveillance and defense.
• China has objected and increased nearby patrols while directing stronger pressure toward the Philippines.
• Vietnam and the Philippines use communication and encounter procedures to manage activity around neighboring positions.
• Maritime entitlements remain governed by the natural features and the law of the sea.
• Reclamation damages marine habitats and creates continuing maintenance costs as storms and rising seas threaten low lying platforms.