The United States and China have sent warships to the multinational naval drills that began in Indonesia on Monday, despite the rifts between the two powers.
Washington and Beijing are engaged in fierce competition on diplomatic, military, technological and economic fronts.
The US Navy has sent a littoral combat ship to the exercise, a US embassy spokesperson in Jakarta told AFP on Sunday.
The drills will allow the United States to "join together with like-minded nations, our allies and our partners to work on solving common challenges" such as humanitarian and disaster response, the spokesperson said.
The Chinese defence ministry said last week that it would send a destroyer and a frigate at the invitation of the Indonesian navy.
Australia and Russia were also expected to send warships, according to an Indonesian military list seen by AFP.
Officials said there would be 17 foreign vessels involved in the drills, which will focus on non-military operations with key allies.