The Philippines and the United States kicked off a joint military exercise on Monday. The “Balikatan” training comes at a time when tensions are soaring between Manila and Beijing over territorial claims in the South China Sea.

A total of over 16,000 troops from the two countries are taking part in the annual exercise. About 250 personnel from France and Australia will also join the activities, which run through May 10.

Philippine Armed Forces Chief of Staff Gen. Romeo Brawner said at the opening ceremony, “We understand the importance of maritime cooperation in addressing the complex challenges that threaten peace and security in our region.”

Vessels from the Philippines, the US and France will hold drills in areas within Manila’s exclusive economic zone, which overlaps Beijing’s claims in the South China Sea.

On the western island of Palawan, US and Philippine troops will conduct live-ammunition drills with the High Mobility Artillery Rocket System, or HIMARS, which is capable of long-range precision strikes.

Beijing has been flexing its muscles in the disputed waters of the South China Sea, including by blocking Philippine supply vessels and firing water cannon at them.

Manila aims to strengthen security cooperation with its partners through the multilateral exercise to keep China in check.