The United States sustained a significant military presence in the South China Sea throughout 2025, marked by increased reconnaissance, joint exercises, and alliance-based activities, according to a report released on Friday by the Beijing-based South China Sea Strategic Situation Probing Initiative. The group, which produces annual assessments of U.S. military operations in the region using open-source data, noted a complex pattern of activity shaped by global strategic demands.

Since 2009, U.S. operations targeting China in the South China Sea have escalated sharply. While the U.S. Navy and Air Force faced constraints in 2025 due to ongoing tensions in the Middle East and elsewhere, American forces nevertheless maintained robust engagement in and around the maritime area. However, the report highlighted signs of strain in certain operations. For instance, deployments involving carrier strike groups, amphibious ready groups, ocean surveillance vessels, and bomber sorties showed indications of fatigue, reflecting the demands of other worldwide contingencies and limitations in the production of military platforms. The frequency of "freedom of navigation" operations also declined during the year.

Conversely, the report detailed a marked rise in close-in reconnaissance flights, training exercises, and coordinated actions with allies and regional partners. Unmanned aerial systems accounted for a significant portion of this uptick, with MQ-4C Triton and MQ-9 Reaper drones operating from bases in Okinawa, Japan, and Clark Air Base in the Philippines. These platforms contributed approximately 30 percent of U.S. reconnaissance sorties targeting Chinese positions in the South China Sea, leveraging their long endurance and reduced operational risks. Overall, U.S. reconnaissance aircraft flew about 1,200 sorties in the area during 2025, supported by 197 ship-days of operations involving ocean surveillance and survey vessels.

The report noted a seasonal pattern in reconnaissance activity, with peaks at the start and end of the year, often corresponding with major Chinese military deployments or large-scale U.S. naval presence. Traditionally, reconnaissance missions have launched from Kadena Air Base in Okinawa, but increased utilization of Philippine bases has been observed in recent years as intelligence, surveillance, and reconnaissance (ISR) assets shifted forward.

Submarine activity also remained a notable feature, with at least 11 U.S. nuclear-powered submarines reported in the South China Sea and surrounding waters, serving a deterrent function. Additionally, U.S. bomber deployments decreased compared to previous years, with seven operations involving 13 B-52H and B-1B sorties recorded. Meanwhile, four carrier strike groups conducted nine deployments to the South China Sea in 2025, three of which were subsequently redirected to the Middle East.

Experts interpreting the findings suggest that U.S. military operations in the region serve multiple purposes, including deterrence, intelligence collection, coordination with allies, and preparation for potential conflict. Hu Bo, director of the reporting initiative, emphasized that while these activities do not dramatically alter the military balance or present a direct threat to China, they carry political and diplomatic implications. Hu contended the main goal is to raise tensions and encourage Philippine actions against China, though overall U.S. strategy in the area has seen little change since 2009. The report pointed to operational limits caused by competing global priorities and platform shortages, resulting in overextension and fatigue within U.S. forces.

Military commentator Zhang Junshe observed that the high tempo of U.S. air, surface, and underwater activity reflects continuing American focus on the Western Pacific and Asia-Pacific regions as strategic priorities. He noted that operations along the so-called first island chain aim to maintain pressure on China, bolster alliances with countries such as Japan and the Philippines, and gather intelligence on Chinese military developments.