The Philippines is actively upgrading its facilities on two islands it controls in the disputed Spratly chain in the South China Sea, satellite images reviewed by Radio Free Asia have revealed.
The expansion of the airstrip on Thitu Island and the port on Nanshan Island aims to strengthen Manila’s physical presence in the Spratlys in response to recent Chinese escalations in the Spratly archipelago, a scattering of hundreds of small islands, atolls and reefs claimed by many different countries, experts said.
Once completed, Manila will have better access to the two islands, easing supplies and other logistical challenges, thereby improving preparedness to respond to emergencies in the territory it considers part of its exclusive economic zone, they said.
“Hope” for a bigger track
Thitu, called Pag-asa, meaning “Hope” in Tagalog, is the larger of the two islands and is the only Philippine-administered island in the Spratly Islands with a permanent civilian population. It was first occupied by the Philippines in 1974 and is also claimed by China, Taiwan and Vietnam. Its most significant man-made feature is a 1.3 kilometer (0.8 mile) airstrip.
In its 2025 budget, Manila set aside 1.65 billion pesos ($27 million) to expand the runway to 1.5 kilometers (0.93 miles), a length long enough to accommodate some variants of the F-16 fighter jet, as well as light combat and transport aircraft. An additional 300 million pesos ($5 million) was set aside for the construction of a sheltered port.
Satellite images captured by Planet Labs confirm that construction began shortly after the budget was approved and continues through May 2026.
The approximately 200 meter (656 ft) extension appears to extend over a previously submerged area.
In an image from April 2, a barge can be seen on the western part of the runway, likely delivering construction materials.
The runway extension marks a significant shift in the Philippines’ position to strengthen the resilience of its outposts in the South China Sea, Harrison Prétat, deputy director of the Washington-based Asia Maritime Transparency Initiative, told RFA.
“I think the real recent drivers have been the tensions between China and the Philippines at Second Thomas Shoal, basically between 2021 and 2024,” Prétat said.
The Second Thomas Shoal, located about 224 kilometers (139 miles) from Thitu, has been a flashpoint between the two countries since 1999, when the Philippines deliberately beached a navy ship on the shoal and stationed troops on board. The ship-turned-outpost, which requires constant resupply from the Philippine Coast Guard and Navy, has been at the center of escalating clashes since around 2021.
China began using coast guards and warships to interfere and block these resupply missions from the Philippines. Tensions came to a head in the summer of 2024, when Chinese personnel rammed and boarded Philippine ships and a Filipino sailor lost a thumb in the incident.
Soon after, Manila and Beijing reached an agreement to reduce tensions on the shoal, but both sides recognized that the situation had already become too dangerous and unstable, Prétat noted.
“In that context, if you’re looking at improvements to the Thitu Island runway, it makes sense,” he said. “The more they can strengthen the access and logistical capabilities of their outposts, I think it makes them a little more resilient to a situation like Second Thomas Shoal.” »
Zheng Zhihua, an associate professor specializing in maritime affairs at Shagnhai Jiao Tong University, told the South China Morning Post that Beijing would be very concerned if US forces could use the island’s facilities. He added that if the expanded airstrip and shelter ports accommodate U.S. military aircraft or U.S. Coast Guard vessels, it could shift strategic pressure from maritime maneuvers to China.
The small port in a “vast” sea
Nanshan Island is the eighth largest natural island in the Spratly Islands, located 158 km east of Thitu. Called Lawak, meaning “vast” in Tagalog, the Philippines first took possession of it in 1974 and is the fourth largest island occupied by the Philippines – located far from the main areas of Chinese maritime activity in the region.
Satellite images captured from October 2025 to April 2026 show that port expansion on Nanshan Island continues, but is only in its early stages.
The Philippine government has earmarked more than 1 billion pesos ($27 million) for the Nanshan Island sheltered port facility to replace the current port, which has a narrow entrance channel that is too shallow for large ships.
Experts believe that the improvements in Nanshan Island would undoubtedly enhance the docking capabilities of the Philippine Coast Guard and strengthen enforcement operations in the region.
“I think the main impact will be on the ability of the Philippines to continue to use these facilities,” Prétat said. “We don’t know yet what the port will look like because it’s early, but if they could have a more accessible port, it would make this outpost a little easier to resupply and easier to operate from.”
Strong diplomatic messages
Philippine officials have linked the infrastructure project to pointed diplomatic messages. In February, Congresswoman Risa Hontiveros and Philippine Coast Guard spokesperson Jay Tarriela visited Thitu Island, meeting with local residents and issuing a strong declaration of sovereignty. During the visit, Hontiveros said: “We will never abandon the Spratly Islands, including Thitu. »
On April 9, the Philippines unveiled a new Coast Guard command base on the island in an official ceremony attended by Transportation Secretary Giovanni Lopez, Senator Erwin Tulfo and Coast Guard Commander Admiral Ronnie Gil Gavan, who said the base represents a permanent step to demonstrate that the Coast Guard is ready to defend the country’s interests in the waters, its fishermen, their livelihoods and, most importantly, its sovereignty.
Prestat said the Philippine Navy is still at a disadvantage in the Spratly Islands compared to China, which has a large coast guard fleet and a network of large bases throughout the South China Sea, allowing it to deploy ships to the region at short notice.
“These two expansions – on Thitu Island and Nanshan Island – are part of the Philippines’ efforts to increase its patrols and increase its activities in the South China Sea,” Prétat said. “The Philippines is trying to enhance that capability as much as possible to keep its ships in place – to monitor what’s going on, have maritime domain awareness, access rotational troops, provide logistics and maintain some form of presence. »
Edited by Eugène Whong.