It's now widely observed that Morrison and President Donald Trump have struck an early bromance, demonstrated by the dinner Trump hosted for Morrison at the G20 and now the planned gold star reception.

Never mind that many Western leaders view with the deepest concern Trump's erratic foreign policy, leading to caution in their comments. Morrison last weekend happily praised the president as "a strong leader, who says what he's going to do and then goes and does it. ... I can always rely on President Trump to follow through on what he says".

Key to this flourishing relationship is Trump's assessment of Morrison. As Herald Sun columnist Shaun Carney, explaining "Why POTUS loves ScoMo", wrote this week, "Morrison fits Trump's requirements pretty much down to a tee. Morrison is a conservative and an election winner. Trump loves winners." And of course there is Morrison's ministerial record on border security.

Even Malcolm Turnbull received some generally favourable rub off from the government's tough line on people smuggling. It was one point referenced positively (sort of) by Trump during that excruciating phone conversation in which Turnbull begged the then-new president to honour Barack Obama's deal to take refugees from Nauru and Manus. Turnbull and Morrison are very different, but there's a similarity in their approaches to dealing with this idiosyncratic president. Turnbull sought, and Morrison seeks, to establish a link-in with Trump on a personal basis.

Turnbull made his pitch with the line that "I am a highly transactional businessman like you". In the Turnbull time, Trump did reluctantly agree to honour the refugee deal, and Australia - aided by a range of US advocates, including members of Congress - won exemptions from Trump's imposition of steel and aluminium tariffs. (These days Trump is somewhat irritated that Australian aluminium exports to the US have ballooned.)

It's too early for a detailed read of how Morrison will handle foreign policy generally. But the description by a Liberal colleague has Trumpian overtones: "[Morrison] likes to establish relationships and he likes to be a dealmaker. He likes to be able to demonstrate back home the benefits of these international dealings".

One crucial continuity in Australia's handling of the Trump administration has been the work of Joe Hockey, Australia's man in Washington. A hail-fellow-well-met character, Hockey has been the right man for the Trump era. Simon Jackman, CEO of the United States Studies Centre at the University of Sydney, says: "He's been a remarkably effective diplomat for Australia. He's very tight with the inner [Trump] circle". Topped by his golf diplomacy with the president himself.

As well as schmoozing, Hockey (to be replaced early next year by former minister and one-time Howard chief-of-staff Arthur Sinodinos) is also willing to remind the Americans in forceful terms of how solid an ally Australia has been.

That takes us to a key unknown in this evolving Trump-Morrison relationship. Were the US to resort to the use of military force against Iran, would Trump ask Australia for some involvement? Probably. In such circumstances, Australia's presence would be for the sake of appearances.

If a request ever came, it's close to impossible to believe Morrison would say no. But any involvement would likely be limited to joining international patrols and escorts of oil tankers. Morrison recently said "it's not unheard of to have Australian frigates in that part of the world engaged in maritime operations".

Jackman detects "growing weariness" in Canberra strategic circles at Australia's support of the US's Middle East efforts, especially given Australia's priorities are increasingly with the "step up" in the Pacific. That "step up" is driven primarily by the push of China deeper into the region.

Morrison has already marked out the Pacific as a priority in his foreign policy - one that fans out into the much broader issue of managing relations with China, on which so much of our prosperity depends.

The perennial talk about Australia facing a choice between the US and China is false. This is because the alliance will always have the stronger overall pull, however vital the China relationship is and however specific issues play out.

Despite the aim of keeping Australia's dealing with China calm and pragmatic, experience shows that's near impossible. Irritants keep arising, whether it is Chinese interference in Australia via cyber attacks, pressure in the South Pacific, or, as we saw this week, the fallout from an ABC expose about China's appalling treatment of the Uyghurs.

China will be a major item on the talks menu in Morrison's Washington visit - for which he arrives September 19 - including the US-China trade dispute, put on hold at the G20. One challenge in being feted by Trump is capitalising on the "bestie" status while avoiding the appearance of over-familiarity and identification with a leader Australians don't much like or trust.

This year's Lowy Institute poll showed that, despite their strong recognition of the importance of the alliance relationship for Australia's security (72 per cent) only 25 per cent of Australians had confidence in Trump "to do the right thing regarding world affairs".

On his US visit, it will be important the PM be seen as his own man. He will have a significant opportunity when he takes part in the leaders week at the United Nations in New York. He is expected to address the General Assembly.

However, one notable dilemma could be presented by the UN Secretary-General Antonio Guterres' Climate Summit on Monday, September 23. If Morrison attends, there could be some awkward conversations; if he doesn't, it's a bad look for Australia.