The Philippines and US launched the largest-ever joint military drills in the archipelago nation on March 28, signalling deepening defence ties as fresh tensions surface in the disputed South China Sea.

The war games are the last under outgoing President Rodrigo Duterte, who previously threatened to cancel exercises and axe a key military deal with long-time ally the US as he pivoted towards China.

Nearly 9,000 Filipino and US soldiers will take part in the 12-day training event across the main island of Luzon, which is usually an annual affair but was cancelled or curtailed during the pandemic.

Philippine military chief General Andres Centino said at the opening ceremony in Manila that the largest round of the Balikatan war games reflected the “deepening alliance” between the two countries.

US Major General Jay Bargeron said the “friendship and trust” between their respective armed forces would allow them to “succeed together across the entire spectrum of military operations”.

The exercises will cover maritime security, amphibious operation, live-fire training and counterterrorism, as well as humanitarian assistance and disaster relief.

Recent manoeuvres between the two countries focused on potential conflict in the South China Sea, which Beijing claims almost in its entirety.

Since taking power in 2016 Duterte has moved closer to China, but has faced pushback from the Philippine public and concern in the military wary of Beijing’s territorial ambitions in the waters.

Trillions of dollars in trade pass through the strategic sea and it is thought to contain rich petroleum deposits, making it a frequent source of regional friction.