"It's more about listening and being able to hear from the allies and partners," the acting US defence secretary said in a plane bound for Jakarta.

Indonesia is the first leg of a tour that also includes stops in Singapore, South Korea and Japan.

On Thursday, Shanahan will meet with Indonesian President Joko Widodo after talks with Foreign Minister Retno Marsudi and Defence Minister Ryamizard Ryacudu.

Cooperation on maritime issues with the sprawling Southeast Asian archipelago nation will be at the top of the agenda, as the US looks to offset China's expanding presence in the South China Sea.

In Singapore on Saturday, Shanahan is to meet Chinese Defence Minister Wei Fenghe on the sidelines of the Shangri-La Dialogue regional defence forum.

"I want to identify areas where we can cooperate," Shanahan told reporters accompanying him on the trip, adding that he hoped to have "very candid discussions around intellectual property theft, or militarisation of the South China Sea."

Washington has repeatedly called for "freedom of navigation" in the busy maritime channel as Beijing builds up its military capabilities, while China has accused US ships of breaching its territorial waters.

But Shanahan said rising tensions would not prevent the US from pushing forward with a defence strategy that sees China and Russia as Washington's main rivals.

"We have the capacity to spin a lot of plates," he added.

Washington has deployed some 1,500 troops, an aircraft carrier, a warship, B-52 bombers and a Patriot missile battery in the Middle East, citing "threats" from Iran or pro-government militias toward its interests and troops in that region.