AsianFin -- China and the Philippines have raised their national flags on small sandbars in the South China Sea, intensifying competing claims over strategic waters long viewed as a potential flashpoint for broader conflict.

The symbolic moves took place on Sandy Cay, a cluster of three uninhabited sandbars located near a Philippine military outpost in the disputed Spratly Islands.

The release of the photos coincides with the largest-ever U.S.-Philippines joint military exercises underway in nearby waters, and comes just weeks after U.S. Defense Secretary Pete Hegseth, during his first visit to Asia, pledged to bolster the American alliance with the Philippines to "reestablish deterrence" against what he described as "China’s aggression" in the region.

The South China Sea, a critical maritime corridor bracketed by China and several Southeast Asian nations, is subject to overlapping territorial claims. However, Beijing asserts ownership over nearly the entire waterway, despite a 2016 international tribunal ruling invalidating its expansive claims.

Over the past two decades, China has steadily built up military infrastructure on reefs and atolls across the South China Sea, including runways and ports, far from its mainland shores.

The latest standoff over Sandy Cay not only risks fueling renewed tensions between Beijing and Manila but also presents an early test for the Trump administration’s Indo-Pacific strategy, which has emphasized countering China’s growing influence in the region.