Pompeo’s visit to Indonesia comes amid a five-nation swing through Asia where he has sought to strengthen strategic and economic ties amid rising tensions between the US and China.

In a joint news conference with his Indonesian counterpart Retno Marsudi, he hailed Jakarta’s “decisive action” to protect its sovereignty in the waters near the Natuna Islands, which China also claims as its territory.

Pompeo said China’s claim was “unlawful”.

“I am looking forward to co-operating together in the new ways to ensure maritime security protects some of the world’s busiest trade routes,” Pompeo said in a streamed news conference after his meeting with Indonesia’s foreign minister.

Retno said she wanted a “stable and peaceful” South China Sea where international law is respected.

Pompeo is scheduled to meet Indonesian President Joko Widodo on Thursday, as well as making an address to an Islamic youth group.

Prior to his visit to Indonesia, Pompeo visited India, Sri Lanka and the Maldives. He is scheduled to fly to Vietnam later on Thursday.