Vietnam is building military and maritime infrastructure at 27 sites across at least 18 reefs in the disputed Spratly Islands in the South China Sea, satellite imagery analyzed by Radio Free Asia revealed.
The improvements include ports, runways, military facilities and communications arrays that will improve Hanoi’s maritime and airspace awareness, experts told RFA.
“Hanoi is likely hoping that this development will deter Chinese action against Vietnamese economic activity at sea, including fishing and offshore oil and gas,” Harrison Prétat, deputy director of the Washington-based Asia Maritime Transparency Initiative, or AMTI, told RFA.
The Spratlys are a strategically critical and heavily contested archipelago comprising more than 100 small islands and reefs claimed wholly or in part by China, Vietnam, the Philippines, Malaysia and Brunei. The region is vital for global trade and is rich in fishing grounds and potential oil and gas reserves. No single nation holds universally recognized sovereignty over the islands.
Hanoi’s Objectives
Over the past decade, claimant nations — most notably China and, more recently, Vietnam — have engaged in extensive dredging and construction as a means to increase their footprint in the disputed territories and to bolster their claims.
Vietnam has been particularly aggressive in reclamation efforts, creating an additional 534 acres (216 hectares) of land across the archipelago over the past year, according to AMTI. This was in addition to the 2237 acres (905 hectares) it had already reclaimed over the past five years. The new reclamation areas undertaken in the second half of 2025 are on a much smaller scale as reclaimable areas become more scarce.
More than one project is active on some of Vietnam’s holdings in the Spratlys, including Cornwallis South Reef, Alison Reef and East London Reef.
The aggressive expansion in the Spratlys is Hanoi’s attempt to improve its ability to operate there, Lynn Kuok, the Lee Kuan Yew Chair in Southeast Asia Studies at the Washington-based Brookings Institution, told RFA.
“Vietnam is strengthening the logistical foundations of its presence in the South China Sea,” she said. “By expanding its network of harbors across the Spratlys, Hanoi is making it easier to move personnel, supplies and equipment between its occupied features and the mainland to sustain operations over longer periods.”
Monitoring the airspace
A key part of the new construction will help Hanoi to patrol the skies. At present Vietnam has a single 4000-foot (1,200-meter) runway on Spratly Island, the fourth-largest island in the Spratly chain from which the archipelago gets its name.
A new, much larger runway at Barque Canada Reef will stretch approximately 13,000 feet (4,000 meters) when it is complete.
In addition to the runway, Satellite imagery also confirms that a new communications structure has been installed — according to AMTI, it appears to be a Doppler VHF Omnidirectional Range (DVOR) navigation beacon that will likely provide accurate navigation for Vietnamese aircraft within 100 nautical miles of the island.
AMTI said similar beacons could be seen at the Spratly airstrips controlled by China.
“The navigation beacon at Barque Canada mainly serves to support Vietnamese aircraft navigating the surrounding areas of the South China Sea,” said Prétat. “I would only expect to see another DVOR beacon if they build another new airstrip, but we will likely see other types of communications and sensing facilities built on all the new outposts.”
The improvements to airspace infrastructure indicate a shift in Vietnam’s Spratly development, said Kuok. The first phase was land reclamation, and now the second phase, adding infrastructure to the enlarged islands and reefs, is underway.
“The installation of communications and navigation infrastructure should improve connectivity among the features Vietnam occupies and support aircraft operating in the South China Sea,” she said.
Insurmountable disparity
Despite the construction boom, Vietnam has no realistic path to matching China’s air capabilities, Prétat said.
Beijing already has four airstrips — at Fiery Cross Reef, Subi Reef, Mischief Reef and Woody Island — and will likely add a fifth at Antelope Reef. Additionally, Vietnam’s air force is far smaller and less technologically advanced than China’s.
“Hanoi is likely hoping that this will improve its ability to monitor its maritime areas and deter Chinese grey zone activity, but it won’t change the fact of China’s overwhelming military dominance in the South China Sea,” Prétat said.
China therefore retains substantial advantages in the Spratlys, with roughly twice as much reclaimed land, more extensive military infrastructure and overwhelming advantages in naval, coast guard and maritime militia capabilities, Kuok said.
Tit for tat?
RFA recently reported that Vietnam protested China’s land reclamation activities at Antelope Reef, but Prétat said China may have started those as a reaction to Vietnam’s Spratly expansions.
China’s construction of a new facility at Antelope Reef suggests Beijing wants to keep that gap sufficiently large — perhaps to signal to Vietnam and other Southeast Asian claimants that “catching up” is not an option. Beijing will do what it must in order to maintain its dominance in the South China Sea, he said.
Kuok said she is concerned that Vietnam’s fortification of features it occupies could create additional points of friction with Chinese forces and therefore increase the possibility of incidents or clashes.
But China’s disputes with Vietnam are less of a flashpoint than those Beijing has with the Philippines, she noted, adding that both Vietnam and China have strong incentives to prevent tensions in the South China Sea from spilling over into the broader bilateral relationship, which remains important economically and politically.
Prétat said that Vietnam’s position in the dispute is complicated by its broader relationship with China.
“Vietnam has been very proactive. They fought battles with China in the South China Sea, but they also have a very different set of international relationships,” he said. “On the one hand, they are one of the stronger voices on the South China Sea disputes, but on the other hand they have a unique relationship with China that they have to maintain.”
RFA attempted to contact both the Vietnamese and Chinese governments for comment on the ongoing construction in the Spratly Islands, but neither responded.
Edited by Eugene Whong.