Australia has been mates with America for more than a century, since their troops took Le Hamel off the Germans together, they explained, and the bond forged in battle has endured since.

But the ascent of Donald Trump and his erratic brand of diplomacy - not to mention that infamously testy phone call with Malcolm Turnbull - had Canberra worried.

After Scott Morrison's tour de force of Washington, there should be sighs of relief echoing in the embassy's corridors.

Ahead of the trip and in Washington, the prime minister stuck to his message religiously.

Australia was a close friend the United States had been able to rely on for a long time.

But, Morrison repeated ad nauseam, we were a friend who pulled our weight, who didn't automatically look to the US if we needed a hand.

This was true both in our military efforts and economic ties.

While those around Morrison and his ambassador Hockey might have been sick of the spiel - and the kangaroo-on-eagle mateship logos plastered on everything from caps to lapel pins to notebooks - it was really aimed at an (inattentive) audience of one: Trump.

The president frequently complains about allies he doesn't think are doing their bit, while America's trade deficit with China is at the foundation of his tariff tit-for-tat.

For Morrison, the relationship was perfectly represented in the story of Leslie "Bull" Allen, a digger who rescued a dozen wounded Americans from the battlefields in Papua New Guinea.

Morrison has been working on the tale of Allen for a while.

He relayed it to Marines in Darwin on the eve of Anzac Day, he told it to Trump when they met in Osaka in June, and now he's given the president a statuette of the Australian carrying an American comrade and promised a life-sized version will soon be installed in Washington.

The presidential ears were receptive to the carefully crafted tale of winners and mates.

Trump anointed Morrison at a rally-like event at billionaire Anthony Pratt's new factory in Ohio.

"We're profoundly grateful to be joined today by one of America's greatest friends and most loyal allies - somebody that's become a very good friend of mine," Trump said, to roars from a crowd that had been uncertain about the prime minister earlier in the event.

"He's a great gentleman and they love him in Australia and they now love him in the United States of America, too."

And at the state dinner in the White House's Rose Garden, Trump gave a personal toast that quoted Morrison's great-great-aunt Mary Gilmore, moving the prime minister nearly to tears.

So Morrison has succeeded in leaving a good personal impression (albeit with a president suddenly engulfed in impeachment threats) and shoring up the ties with Australia's most important ally.

But what souvenirs might he take home?

He's had the chance to observe the president's pugilistic relationship with the American press at very close quarters.

"I think this is one of the worst weeks in the history of the fake news media ... You are a joke," Trump said, looking right down the barrel of a camera in a surreal 33-minute encounter in the Oval Office while Morrison sat at his side.

While the Canberra press pack, unused to the invective - or the casual threats to bomb other countries - picked their jaws up off the floor, the Washington reporters barely blinked.

At his final press conference Stateside, Morrison strayed dangerously close to the same territory, complaining people had a "completely false" view of what Australia was doing on climate change.

"Where do they get their information from? Who knows? Maybe they read it, maybe they read it."

Challenged on whether he was calling out "fake news", Morrison insisted he wasn't saying that.

But the impression remained.

At the annual Canberra press gallery charity ball the night before Morrison left for the US, Labor's Anthony Albanese and senior gallery members warned of the threats to a free press that crystallised in the June raids on journalists.

Morrison made a joke about collecting the metadata of everyone in the room.

Australian Associated Press