Diplomacy is fundamental to global leadership and it is especially important to small trade-dependent nations such as New Zealand.
All our prime ministers are diplomatic in choosing their words about other nations and their leaders.
But Ardern has faced a tougher challenge than most.
Trump's anti-science rhetoric around Covid-19, his deliberate failure to condemn conspiracy groups such as QAnon and white supremacist groups like the Proud Boys, his attitudes to women - these things mark him out as unlikeable ... and weird.
Trump is not a politician. He is a brash businessman, and not a particularly good one.
If he thinks something, he says it. He has no filter.
That's what his supporters like about him.
He's a vandal, a wrecking-ball that angry nationalists in the US enabled out of fear of social change.
John Key got to hang out and play golf with Barack Obama who, even if you hate his policies, is a man of charm and grace, a master of social etiquette.
The Key/Obama friendship served as a reminder that most of New Zealand's centre-right politicians sit comfortably within the ideological framework of the US Democratic Party.
You have to head a long way to the right here to find anyone willing to condemn free public health care.
More importantly for New Zealand though, Obama was a believer in multi-lateral global cooperation.
Like both his Democrat and Republican predecessors, he believed in the importance of the United Nations, the OECD, the World Health Organisation and the World Trade Organisation.
These institutions are vital to New Zealand and our efforts to maintain national security.
We cannot defend ourselves from military attack.
Without international cooperation we can't even defend ourselves from commercial bullying.
Trump does not believe in these organisations. He and his administration have sought to dismantle and undermined them at every turn.
So while his behaviour and the damage it is doing to US society is sad to watch, on the global stage, it has serious strategic implications for us.
It's for these reasons that New Zealand is under no obligation to support Trump's nomination for head of the OECD, Chris Liddell, just because he is a Kiwi.
Kiwi White House staffer Chris Liddell is Donald Trump's nomination to lead the OECD. Photo / File
If Ardern needed a reminder of this, then last week's events at the World Trade Organisation provided it.
In what is hopefully its last act of international vandalism, the Trump administration vetoed the appointment of the widely supported candidate for director-general for the WTO
Nigerian candidate Ngozi Okonjo-Iweala was on track to be appointed by consensus, Bloomberg reports.
But Okonjo-Iweala, ironically also a US citizen, was considered by the Trump administration too closely linked to the "pro-trade" officials from the Obama era.
The move has left the WTO in turmoil. It's part of a deliberate pattern of behaviour by Trump trade officials.
It follows efforts to block appointments to the WTO appellant body - which judges international trade disputes.
Since Trump took the White House, the US has blocked all appointments to the body, effectively ending its power to rule on trade disputes.
The trade war with China and the wrecking of the WTO have been largely overshadowed this year by the onslaught of Covid-19.
But economists estimate Trump's trade policies have costs the world trillions in growth - much of it within the US.
Research by the Federal Reserve Bank of New York and Columbia University found US companies lost at least US$1.7 trillion in the price of their stocks due to increased US tariffs against imports from China, according to Forbes.
Trump still tells his supporters that China is paying the tariffs, even though this is false.
The trade war and rise of protectionist policies also knocked almost a full per cent off global GDP last year according to the IMF.
That's before you get to the direct cost to New Zealand exports and the opportunity cost of progress stalling on further tariff reductions.
So it's hard to see how a Trump candidate for the OECD is in New Zealand's strategic interests - even if he was once, in another lifetime, dubbed NZ Herald Business Leader of the Year.
The debate about whether to endorse Liddell flared up in the election-free vacuum of domestic politics last week.
The Greens said no. National and Act said yes.
The Government, wisely, said nothing.
Prime Minister Jacinda Ardern. Photo / Dean Purcell
First and most obviously, they don't need to make a call before the US election.
But endorsing Liddell for parochial reasons is ridiculous - embarrassingly simplistic (as one trade expert put it to me).
Rejecting him to send a message about his involvement in US domestic politics seems equally ill-advised.
New Zealand should stand against Trump and his blustering destructive deal-making style.
We should do so by carefully and diplomatically making rational international policy decisions.
On that basis, amid a strong field, Liddell is not near the top of the list.
