The United States, Japan, Australia and the Philippines have started joint naval exercises in the South China Sea, a move that underscores growing security coordination among the four countries as regional tensions with China remain elevated.

According to Reuters, the drills began on Friday and come amid continuing disputes over control and access in the busy waterway, which has become a central flashpoint in broader Asia-Pacific security rivalry. The exercises are the latest in a series of multinational operations intended to strengthen interoperability and signal support for freedom of navigation.

The South China Sea is one of the world’s most strategic shipping routes and has long been a source of friction because of overlapping territorial claims. Beijing has repeatedly opposed expanded military activity by other countries in the area, while Washington and its partners say their presence helps deter coercion and preserve stability.

The latest drills highlight how the alliance network is adjusting to a more confrontational regional environment. For the Philippines in particular, the exercises reflect deepening defense ties with outside powers as it faces ongoing pressure in waters it considers part of its maritime rights.