When the going gets tough in the US capital, Donald Trump gets going to the greens of one of his private golf clubs — and, it turns out, phones an Australian friend to help keep spirits up.

Joe Hockey may well have become the envy of Washington DC's diplomatic corps, getting a call-up to join the US President in a select foursome for much-needed fairway therapy at the end of another testing week in the White House.

Last weekend had been an especially trying one for Mr Trump. He had commanded more than 100 missiles rain down on Syria, unleashed a Twitter fusillade against the sacked FBI director James Comey and fretted over the seizure of his confidential legal dealings by federal investigators — all while his alleged one-time porn-star lover continued endless rounds of media interviews.

What better than to slip across the Potomac River in a low-key Secret Service motorcade for a nine-hole round at the Trump National Golf Club in Sterling, Virginia?

The President was not going it alone.

From his comfortable ambassadorial residence on Cleveland Avenue, Mr Hockey was summoned to throw in his clubs and join Mr Trump under leaden grey skies on a drizzly morning in Loudoun County.

Upon pulling up to the majestic Trump National clubhouse overlooking the river and the sweeping grounds — rated in the top three new golf courses by Golf Digest in 2016 — Mr Hockey was joined by Fox News anchor Bret Baier and the White House's budget director, Mick Mulvaney.

The morning might have had an Anzac feel to it if the originally-invited former Kiwi businessman-turned senior White House advisor Chris Liddell had not been a no-show, requiring Mr Mulvaney to step in at the last moment.

US media reporters organised as a pool to observe the President's movements from what they described as "the tennis facility" were unable to track the foursome's movement across all nine holes, but one later noted that the Fox News presenter spent much time lobbying the President to appear on his show, Special Report, as it had been 535 days since Mr Baier last had the opportunity.

No observations were conveyed about Mr Hockey's conversations, his round, his attire nor his temperament.

A few days after the outing Mr Hockey succinctly offered, via his embassy, that the President was a "good golfer and good company".

The former treasurer is known to be an enthusiastic, if unaccomplished, golfer while Mr Trump's game has been variously reviewed as "solid" and "pretty good".

A mark of US-Australia relations

Convivial as it apparently was, the Sunday hit-out provides yet another demonstration that Australia counts itself in a small group of nations able to command the highest levels of access to the President and the most senior figures in his administration.

Another more tangible recent measure came in an early exemption from the President's swingeing steel tariffs.

But the Australia-US relationship Mr Hockey was charged with nurturing has not always been smooth in the Trump administration.

Like many countries, Australia was ill-prepared for the businessman's election win and had to scramble to get off on the right foot with Cabinet secretaries and advisers in the President's first year.

Despite wide-scale departures of key contacts including secretary of state Rex Tillerson and economics adviser Gary Cohen, Mr Hockey and his team in Washington, together with his former Turnbull Government ministerial colleagues in Canberra, have played a strong catch-up game since early 2017.

Having made it onto the President's golf buddy list, Mr Hockey now faces the task of ensuring his diplomacy never spears out into the rough again.

As other Washington ambassadors will attest — that's a lonely place to be.