Japan led an annual multinational naval exercise that included the Philippines as an observer for the first time, as Filipino coast guard vessels are increasingly harassed by China in the disputed South China Sea.

The Annualex exercises that began Saturday off Japan’s coast also included the United States, Australia and Canada. Their aim is to demonstrate and increase ways the navies can work together, and show their presence and commitment to defend a “free and open” Indo-Pacific, which the allies say is hampered by China’s growing ambitions that include sweeping territorial claims.

On Saturday, a selected group of journalists, including The Associated Press, flew on an V-22 Osprey aircraft to the USS Carl Vinson aircraft carrier to observe takeoffs and landings of F-35C “Lightning” stealth fighters, as well as F/A-18 Super Hornet jets and E/A-18 Growlers. The Japanese destroyer Hyuga showed its presence next to the carrier.

The exercise comes in the wake of the latest confrontation between the Philippines and China in the South China Sea on Friday, adding to the territorial disputes that risk turning into a more serious armed conflict.