Admiral Harry Harris made his way on stage and looked down at the large, impressive audience before him that included US President Donald Trump, Australian Prime Minister Malcolm Turnbull, billionaires Rupert Murdoch and Anthony Pratt and golf champion Greg Norman.

It was the evening of May 4, 2017, and the VIPs were in the belly of the USS Intrepid, a decommissioned World War II aircraft carrier docked on the Hudson River next to the metropolis of New York City.

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They were there to commemorate the 75th anniversary of the US-Australian victory over Japan in the Battle for the Coral Sea.

"Today's Australian and US alliance has assumed liberty's mantle, passed down from the Coral Sea in an unbroken chain, watch to watch, for 75 years," Admiral Harris told the 500 or so VIPs.

"Just as Australia and the United States stood together against tyranny and oppression in the 20th Century, the world expects no less in the 21st."

On Friday Mr Trump confirmed one of the worst secrets in Washington DC and Canberra.

He announced Admiral Harris was his pick to become the next US Ambassador to Australia, a move warmly welcomed by Mr Turnbull with a tweet that ended with: "Look forward to seeing you in Canberra, Harry!"

If, as expected, Admiral Harris is confirmed by the US Senate he will arrive in the Australian capital after heading the US Pacific Command, the most formidable fighting force on the planet.

He commands the US Pacific Fleet and its 200 ships, including five aircraft carrier strike groups, two Marine Expeditionary Forces, the Pacific Air Forces and its 46,000 airmen and civilians and more than 420 aircraft and the Army Pacific's 106,000 personnel and more than 300 aircraft.

PACOM's area of responsibility encompasses half the earth's surface - from the waters off the west coast of the US to the western border of India and from Antarctica to the North Pole.

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On that May evening on the USS Intrepid Admiral Harris spoke fondly of the strong US-Australian relationship and the results of a meeting he just had with Australian Air Chief Marshal Mark Binskin.

"I had a terrific consultation earlier today where we reaffirmed the strength of the US-Australia military mateship and candidly, our biggest hurdle was whether to spell 'Defense' with a 'C' or an 'S'," Admiral Harris, drawing laughs, said.

"I think we were able to work it out."

Admiral Harris' pending arrival in Canberra will not draw laughs in Beijing.

Australia has managed to walk a fine line between old ally the US and the Asian power and Admiral Harris' arrival could complicate that.

The tough-talking, no-nonsense son of a US Navy man and Japanese mother has stood toe-to-toe with China, including calling the Asian power's construction of artificial islands in the South China Sea the "Great Wall of Sand".

In April last year during testimony to the US House Armed Services Committee he also called out China.

Great to see Admiral Harry Harris nominated by @realDonaldTrump as US Ambassador to Australia. Look forward to seeing you in Canberra, Harry! pic.twitter.com/YHvu1NQ4BN — Malcolm Turnbull (@TurnbullMalcolm) February 10, 2018

"China has fundamentally altered the physical and political landscape in the South China Sea through large scale land reclamation and by militarising these reclaimed features," the Harvard and Oxford educated admiral, often described as a China hawk, told the committee.

"Beijing continues to press Japan in the East China Sea, is stepping up diplomatic and economic pressure against Taiwan, and is methodically trying to supplant US influence with our friends and allies in the region.

"Furthermore, China is rapidly building a modern, capable military that appears to far exceed its stated defensive purpose or potential regional needs.

"China's military modernisation is focused on defeating the US in Asia by countering US asymmetric advantages."