The US and its Asian allies have expressed growing concern about China's increasing assertiveness in the Pacific, but Washington has said the drills are not aimed at any country.

The annual exercises known as Super Garuda Shield kicked off in Baluran, East Java, with more than 2,000 American troops taking part.

The Indonesian military said it deployed 2,800 troops to join the drills, which were opened at a Thursday morning ceremony by the country's military chief, Yudo Margono.

"Super Garuda Shield 2023 builds on last year's tremendous success," General Charles Flynn, commanding general of US Army Pacific, said in a statement.

"This joint, multinational training exercise displays our collective commitment and like-minded unity, allowing for a stable, secure, and more peaceful, free and open Indo-Pacific."

The two-week exercise will be held at multiple training locations in East Java and is being joined by participants from Australia, Japan, Singapore, France and Britain.

Training will include expert academic exchanges and professional development workshops, a command and control simulation, an amphibious exercise, airborne operations, and a simulated airfield seizure.

There will also be a combined joint field training that culminates with a live-fire event, the US embassy said in a statement.

Last year's exercises were held after Beijing staged unprecedented war games around Taiwan, which it claims as part of its territory.

Brazil, Canada, Germany, India, Malaysia, the Netherlands, the Philippines, South Korea, New Zealand, East Timor, Brunei and Papua New Guinea are participating in the exercise as observer nations.