Shanahan sets off Tuesday on a tour of Asia that will take him to Indonesia, Singapore, South Korea and Japan, the Pentagon said in a statement.

In Singapore, he will give a speech on the US defense strategy for the Indo-Pacific region at the Shangri-La Dialogue, which is held each year in the Southeast Asian city-state.

The International Institute of Strategic Studies, the conference organizer, announced on its website that Chinese Defense Minister Wei Fenghe was taking part.

"We are doing a pull-aside with the Chinese counterpart in Singapore," the Pentagon official said, speaking on condition of anonymity.

The new US defense strategy identifies Russia and China as the two top potential adversaries of the United States.

Reproaching Beijing for militarizing the South China Sea, the United States has been conducting regular "freedom of navigation" operations in the Pacific, sending warships near disputed islands and overflying international airspace.