The United States will back Australia's expanded naval base in Papua New Guinea, Vice President Mike Pence has announced.
The United States will join forces with Australia in the development of a new naval base to be built in Papua New Guinea, US Vice President Mike Pence has announced.
Mr Pence told an Asia Pacific Economic Cooperation meeting the US will contribute to the expansion of the Manus Island facility.
Australia has been working on a plan to expand the Lombrum Naval Base on Manus, in a bid to lock China out from developing its own base in PNG.
"The United States will partner with Papua New Guinea and Australia on their joint initiative at Lombrum Naval Base," Mr Pence said.
"We will work with these two nations to protect sovereignty and maritime rights in the Pacific Islands."
Mr Pence appeared to throw down the gauntlet to China on trade and security in the Pacific region.
"We have taken decisive action to address our imbalance with China," Mr Pence declared.
"We put tariffs on $US250 billion ($A341 billion) in Chinese goods, and we could more than double that number."
"The United States, though, will not change course until China changes its ways."
The stark warning will likely be unwelcome news to financial markets which had hoped for a thaw in the Sino-US dispute and perhaps even some sort of deal at a G20 meeting later this month in Argentina.
Earlier, Chinese President Xi Jinping said protectionist actions were shortsighted and doomed to fail, in his speech ahead of the APEC summit at which US-China trade tensions are likely to take centre stage.
"Attempts to erect barriers and cut close economic ties work against the laws of economics and the trends of history," he told business leaders on the sidelines of the summit.
"This is a short-sighted approach and it is doomed to failure," Xi told business leaders on the sidelines of the summit."
The Chinese leader also took a direct swipe at US President Donald Trump's administration.
"We should say no to protectionism and unilateralism," he said.
The US and China have become embroiled in a trade war that experts warn could be catastrophic for the global economy, with the world's top two powers going head to head.
The pair have imposed tariffs worth billions of dollars of each other's goods and there is little sign of an immediate easing in tensions, with both sides threatening to step up action if necessary.
But There was no hint of compromise from Mr Pence.
"China has taken advantage of the United States for many years. Those days are over," he told delegates gathered on a cruise liner docked in Port Moresby's Fairfax Harbour.
He also took aim at China's territorial ambitions in the Pacific and, particularly, Xi's Belt and Road Initiative to expand land and sea links between Asia, Africa and Europe with billions of dollars in infrastructure investment.
"We don't offer constricting belts or a one-way road," Mr Pence said.
While not referring directly to Chinese claims over various disputed waters in the region, Pence said the US would work to help protect maritime rights.
"We will continue to fly and sail where ever international law allows and our interests demand. Harassment will only strengthen our resolve."