Subi Reef Base

China's development of Subi Reef began in 1988 with the construction of a small concrete platform, which eventually served as the foundation for a major military facility. Located roughly 16 miles southwest of Philippine-occupied Thitu Island, the reef remained a modest outpost for over two decades — a stark contrast to its natural state. Between 2014 and 2016, extensive dredging and land reclamation operations permanently transformed the low-tide elevation into a 3.95-square-kilometer artificial island, known as Zhubi Jiao in Chinese. According to satellite data analyzed by the Asia Maritime Transparency Initiative (AMTI), the outpost now features a 3,250-meter concrete runway designed to accommodate fighter jets, transport aircraft, and long-range bombers.

The transformation of the reef into an operational joint base has been closely monitored by regional security services. Reports from the Center for Strategic and International Studies (CSIS) indicate that the base is equipped with hardened aircraft hangars, buried ammunition storage, and point-defense weapon systems. While primarily designated for logistical support and maritime surveillance, the outpost has been heavily fortified to restrict regional access. Security monitors have documented the presence of advanced radar installations, mobile missile shelters for surface-to-air systems, and tracking arrays designed to intercept naval communications in the northern Spratlys.

Sovereignty over Subi Reef remains a highly contentious international issue, placing it at the center of territorial disputes between China, the Philippines, Vietnam, and Taiwan. In 2016, the Permanent Court of Arbitration in The Hague issued a landmark ruling concluding that Subi Reef is legally a low-tide elevation with no territorial sea of its own. Consequently, the tribunal determined that Beijing's island-building activities did not create any new maritime rights. While China rejected the tribunal's findings and maintains de facto control over the facility, neighboring countries continue to challenge its operations, particularly due to the base's close proximity to inhabited features such as Thitu Island.