The navies of the Philippines, the United States and Japan carried out joint maritime drills in the South China Sea on Sunday, according to Reuters. The exercise came as regional tensions remain high over competing territorial claims and China’s growing military presence in the area.

The drills reflect deepening security cooperation among the three allies as they seek to strengthen coordination at sea. The South China Sea remains one of Asia’s most sensitive flashpoints, with overlapping claims involving China, the Philippines and other coastal states.

Reuters said the exercise was held against the backdrop of ongoing diplomatic friction and repeated encounters between vessels in disputed waters. For Manila, the drills also signal continued support from Washington and Tokyo as it faces pressure in waters it considers part of its maritime domain.

The latest operation adds to a series of multilateral activities aimed at deterring escalation and signaling that the allied navies intend to remain active in the region.