In a show of force on Sunday in the South China Sea, where Beijing’s aggressive attempts to press its territorial claims have alarmed many, the United States, Japan, Australia, and the Philippines will conduct their first joint naval drills, including anti-submarine warfare training.

According to a joint statement released by their defence chiefs on Saturday, the four treaty allies and security partners are conducting the drills to protect “the rule of law that is the foundation for a peaceful and stable Indo-Pacific region” as well as freedom of navigation and overflight.

The four nations reiterated their position that a 2016 international arbitration decision, which rejected China’s broad claims on historical grounds, was definitive and legally enforceable, even though China was not specifically addressed in the declaration.

China has rejected the decision, declined to take part in the arbitration, and is still defying it. Following a protracted maritime conflict, the Philippines took its claims with China to international arbitration in 2013.