Thousands of military personnel from Indonesia and the United States are participating in joint drills for two weeks described as the largest ever between the two countries.

The exercises, focused on island defence, are being held in three locations -- Sumatra, Kalimantan and Sulawesi -- from August 1 to 14, the Indonesian military said Wednesday.

More than 2,100 Indonesian military personnel and 1,500 from the US army are involved in the drills, part of the yearly Garuda Shield exercises organised since 2009, it added.

The American soldiers landed in coronavirus-wracked Indonesia in late July and were tested for Covid-19 on arrival.

Indonesian army chief of staff Andika Perkasa said the drills were aimed at improving relations between the countries and upgrading the skills of both militaries.

They include field training, live fire, aviation and medical exercises. 

"Hopefully Garuda Shield will create future leaders of the Indonesian army who are both professional and up to international standards," Perkasa said. 

The United States has been strengthening its presence in the Asia-Pacific region and wooing allies as competition heats up with China.

Despite strong security ties with Washington, Indonesia has shown a willingness to maintain a balance in its relations between the United States and China, a key economic partner. 

During his trip to Singapore last week US Secretary of Defence Lloyd Austin said Beijing's territorial claims in the South China Sea had "no basis in international law".

US Vice President Kamala Harris is also scheduled to visit Singapore and Vietnam later this month.