Los Angeles: US Secretary of State Rex Tillerson has raised the prospect of Australia joining the US, Japan and India in a powerful strategic alliance to promote "a free and open Indo-Pacific".

Mr Tillerson, in a speech and question-and-answer session at the Centre for Strategic and International Studies in Washington DC on Wednesday, described threats faced in the region from cyber attacks, North Korea and China's provocative and undermining actions.

Secretary of State Rex Tillerson speaks about the US relationship with India, at the Centre for Strategic and International Studies. Credit:AP

America was benefiting from a US-Japan-India trilateral agreement, but he said there "is room to invite" Australia to anchor the relationship between the democratic nations.

"There's an important part of the South Pacific that also we think needs an important pinpoint as well," Mr Tillerson said.