MANILA, June 4 - Satellite photographs captured in late May indicated the presence of a structure at the mouth of Scarborough Shoal, one of the region's most contested maritime features, but follow-up imagery suggests the object is no longer visible.
Philippine officials said on Wednesday they are probing reports about a newly observed structure at the shoal, which China has effectively controlled at various times since 2012. Defence Secretary Gilberto Teodoro told reporters on the sidelines of the Shangri-La Dialogue - a regional defence forum - in Singapore on Saturday that he had received raw information pointing to the possible presence of such a feature.
Commercial satellite imagery examined by analysts showed anomalies on several dates. Photographs taken on May 27, 29 and 30 displayed what an analyst at Vantor, a commercial satellite imagery provider, identified as possibly a floating raft or buoy positioned at the opening of the atoll. The May 27 and May 29 images also revealed what appeared to be a barrier extending across the atoll.
On May 28, U.S.-based maritime monitoring group SeaLight posted on X an image of Scarborough Shoal showing what it described as a "small, reflective object clearly distinguishable on the reef flat near the lagoon entrance." SeaLight said its review of additional images supported the view that the item was "a persistent feature rather than a transient optical artifact." Their statement was based on a comparison of multiple satellite passes.
However, imagery taken on June 1 by Vantor did not show the suspected structure, marking the first reported indication that the feature had disappeared from the reef flat. That gap between the late-May sightings and the June 1 image has prompted the Philippine government to investigate the sequence of events and verify the nature of the object observed in the earlier pictures.
Requests for comment to China's defence ministry and its embassy in Manila did not receive an immediate response.
Scarborough Shoal, which China refers to as Huangyan Dao, sits near significant shipping lanes and is prized for its fishing resources and a turquoise lagoon that can shelter vessels during storms. Diplomatic and security analysts have long warned that recurring confrontations around the atoll - including frequent clashes between Chinese coast guard vessels and Philippine fishermen in recent years - carry the risk of escalation.
The area was the subject of a landmark 2016 ruling by the Permanent Court of Arbitration on several South China Sea issues, though that decision did not determine sovereignty over Scarborough Shoal. The court found that actions amounting to a blockade at the shoal violated international law because it had been a traditional fishing ground for multiple countries, including China, the Philippines and Vietnam.
In the past year, China announced the creation of a national nature reserve covering the shoal, a move the Philippines criticized as a "clear pretext for occupation." The announcement further heightened tensions between the two countries.
Chinese military and coast guard vessels carried out patrols in the area on Sunday, shortly after Philippine and U.S. forces concluded a five-day maritime exercise in the same waters - the third bilateral drill this year intended to bolster interoperability and maritime security.
Key points:
- Late-May satellite images showed a possible floating raft or buoy and a barrier at the entrance to Scarborough Shoal; a June 1 image did not show the feature.
- The Philippines has opened an investigation into the reported structure; defence officials received raw information about the development during a regional defence forum.
- The situation touches on regional security and maritime interests, intersecting with fisheries, shipping lanes and defence cooperation between the Philippines and the United States.
Risks and uncertainties:
- Uncertainty over the nature and origin of the object observed in late-May imagery - impacts maritime security and fishing sectors.
- Potential for further confrontations around the shoal given Chinese patrols and recent joint Philippine-U.S. maritime exercises - impacts defence and regional trade routes.