"We are deeply concerned by China's increasingly aggressive and bullying behavior in the Taiwan Strait, and elsewhere in the region," US Defense Secretary Lloyd Austin said as he welcomed his counterparts from Australia and Japan to the US military headquarters for the Pacific region.

"Our interest lies in the upholding of the global rules-based order. But we see that order under pressure in the Indo-Pacific as well, as China is seeking to shape the world around it in a way that we've not seen before," said the Australian minister, Richard Marles.

The United States is pressing a diplomatic offensive to counter Chinese influence in the region.

On Thursday Washington announced an $810 million aid package for Pacific Island nations where the United States plans to intensify its diplomatic presence.

Vice President Kamala Harris traveled last week to Japan and South Korea and said the United States would act without fear or hesitation throughout Asia, including the Taiwan Strait.

Beijing considers Taiwan to be part of China and also claims the thin and busy channel of water that separate the two.

Harris also traveled to Seoul and visited the demilitarized zone between the two Koreas. Her visit was designed to show Washington's commitment to defending South Korea against North Korea.