Philippines DFA Files Diplomatic Protest Against China's 'Marine Nature Reserve' Claim at Scarborough Shoal — Carpio Warns of Civilian-to-Military Conversion Pattern

The Philippine Department of Foreign Affairs filed a diplomatic protest on May 11, 2026 against China's declared 'marine nature reserve' at Scarborough Shoal (Huangyan Dao), escalating the diplomatic response to China's latest institutional moves at the disputed feature. Former Supreme Court Associate Justice Antonio Carpio, the Philippines' leading legal authority on South China Sea law, issued a public warning on May 10 that China's marine nature reserve declaration follows an established civilian-to-military conversion playbook: at both Fiery Cross Reef and Subi Reef in the Spratly Islands, Chinese construction began with facilities described as weather monitoring stations, lighthouses, and environmental installations before transitioning into permanent military bases armed with HQ-9B SAMs, YJ-12B anti-ship missiles, and airstrips. Carpio warned that a 'marine nature reserve' designation at Scarborough Shoal could be used to: (1) provide legal cover for constructing permanent infrastructure at the lagoon entrance under an environmental conservation framework; (2) exclude Philippine fishermen and government vessels under conservation law rather than just coast guard enforcement, tightening the de facto blockade that has caused a 75% income decline for Filipino fishers since 2012; and (3) establish administrative structures that consolidate China's institutional control over the shoal beyond its current de facto presence. Under international law, no state has the authority to establish a 'marine nature reserve' in contested waters that would exclude another UNCLOS state's nationals from traditional fishing grounds without that state's consent. The 2016 PCA ruling found China violated the Philippines' rights to fish at Scarborough Shoal and found the shoal to be a 'rock' entitling it only to a 12 nm territorial sea. The DFA's protest note cited UNCLOS, the PCA ruling, and Philippine sovereign rights as the coastal state. The marine nature reserve development is the third escalatory Chinese measure at Scarborough Shoal in five weeks: the April 10-11 floating barrier (352 meters, blocking the lagoon entrance), the May 9 CCG Chuanshan rights-safeguarding training, and now the marine nature reserve institutional claim. Combined with the ongoing Reed Bank/Iroquois Reef standoff (Day 3) and the BRP Sierra Madre garrison at Second Thomas Shoal, the Philippines now faces three concurrent active SCS confrontations — with a new institutional dimension at Scarborough that could be a precursor to physical construction.