Mr Pompeo and Defense Secretary Mark Esper touched down in Australia on Saturday ahead of Sunday's Australia-US ministerial meetings at NSW Parliament House.

They will later meet Opposition Leader Anthony Albanese before dining with Prime Minister Scott Morrison.

Alongside Australian Foreign Minister Marise Payne and Defence Minister Linda Reynolds, Mr Pompeo said the time was right for the US and Australia to do much more together in the Indo-Pacific.

"Let me be clear - the United States is a Pacific nation. We care deeply about what happens here and we're here to stay," Mr Pompeo told reporters.

"We think of this as an unbreakable relationship - grounded in our shared values of democracy, the rule of law and human rights."

The US and Australia wanted to help countries prosper through trade and investment, Mr Pompeo said, rather than "zero-sum deals where one wins and the other risks losing" - a clear swipe at strategic rivals China as they press on with their Belt and Road Initiative for regional infrastructure.

He also lauded the Morrison government's "Pacific step-up", as well as a shared concern for escalating tension in the South China Sea, where China has developed and militarised contested atolls and reefs.

"We're both concerned about China's militarisation of the South China Sea, both keeping an eye on investment that mires our friends in debt," Mr Pompeo said.

Dr Esper has previously accused China and Russia of seeking to displace the US and "shift the balance of power in their favour" and told US reporters the world had returned to "an era of great power competition".

Senator Payne congratulated Dr Esper for his recent appointment to the Defense portfolio and said the countries' vision for the region was shared.

They would both look to contribute to "sustainable" infrastructure creation, adhere to international law and deepen relationships with other countries in the region such as Japan, India and Indonesia.

"It's important to reinforce that without strong US engagement, the region that we all want, the region we need, can't be achieved," Senator Payne said.

"That's a region in which all states are respected, regardless of size or power.

"The strong Australia-United States alliance can be the basis for deepening our relationships elsewhere."

Mr Pompeo later addressed a Centre for Independent Studies forum with Senator Payne, and will head to Micronesia on Monday.

Mr Morrison has established a solid relationship with US President Donald Trump and is due to attend a state dinner at the White House next month - just the second state leader to receive the honour during the Trump administration.

"Prime Minister Morrison and President Trump had a great meeting last month in Osaka (at the G20 summit) and we've had great conversations as well," Mr Pompeo said.

"We want all Australians to know they can always rely on the United States of America."

Australian Associated Press