A remote sandbar in the South China Sea—Sandy Cay—is once again at the center of a three-way maritime standoff involving China, the Philippines, and Vietnam. In April 2025, Chinese coast guard officers raised their national flag on the cay, a move broadcast proudly by Chinese state media as an assertion of sovereignty. Within days, Philippine forces responded with their own flag-planting and patrol mission. Vietnam, meanwhile, lodged formal protests against both sides.
The cay sits roughly 2 kilometers from Thitu Island, which is controlled by the Philippines and known locally as Pag-asa. Though uninhabited and just a stretch of sand, Sandy Cay’s legal and strategic value is significant. Its status as a naturally formed landmass above water at high tide means it can generate a 12-nautical-mile territorial sea under international law, as confirmed by the Permanent Court of Arbitration’s 2016 ruling on the South China Sea. For any country staking a claim, that’s a big deal.
Flag-Planting and Face-Offs
On April 27, the Philippines dispatched a joint force of navy, coast guard, and maritime police units to Sandy Cay and nearby features. Photos and video from the mission, released by the National Task Force–West Philippine Sea, show rubber boats landing and personnel raising Philippine flags. Officials reported that the cay was unoccupied at the time, disputing earlier claims by China that it had already secured control.
The Chinese action occurred just days before this, around mid-April. State-run media outlets released images of Chinese coast guard members on the cay, saying they were conducting “sovereign enforcement.” The timing wasn’t lost on observers—it came in the middle of the Balikatan military drills between the U.S. and the Philippines, the largest such exercises to date.
Vietnam Pushes Back
Vietnam didn’t stay quiet. On May 3, Hanoi delivered diplomatic protests to both China and the Philippines, accusing them of infringing on its territorial rights. Vietnamese officials described Sandy Cay as part of their Truong Sa (Spratly) island group and warned all parties against further unilateral moves.
This is notable. While Vietnam regularly clashes with China over maritime issues, it rarely takes on the Philippines so directly. But with both Manila and Beijing planting flags, Hanoi made it clear: Sandy Cay isn’t theirs to claim. “Respect for international law” was the core message of Vietnam’s protest, echoing its long-held position on South China Sea disputes.
Strategic Calculations
The flare-up over Sandy Cay underscores the complex and fragile balance in the region. Each move—each flag, each patrol—is more than symbolism. China’s nearby Subi Reef is a heavily fortified military base. Thitu Island, controlled by the Philippines, has its own outpost. Sandy Cay sits between them, barely visible at high tide, yet heavy with meaning.
