Opinion - A kerfuffle at the G20 meeting between Chinese handlers and the American delegation have been exacerbated by somebody in the US intelligence establishment snarking at China using an official Twitter account.
As a freshly minted, desperately keen young journalist I visited China for RNZ during the 50th anniversary of the People's Republic in 1999.
Most of the trip involved making radio documentaries about cultural change, the impending return of Macao and the impact of the gargantuan Three Gorges Dam, then under construction on the Yangtze.
But I also got to gawp at the 50th anniversary parade that processed along the Avenue of Eternal Peace and through Tiananmen Square. That parade is a useful example of the lengths the state is prepared to go to in order to control all eventualities and prevent embarrassment.
The parade was to begin downtown at 10am, but the invited international media had to assemble on the outskirts of the city at 4.30am.
All traffic was banned in central Beijing so I borrowed the hotel manager's bicycle and pedalled for miles along silent, wet streets. It had poured overnight as a result of extensive cloud seeding to ensure a dry, clear day.
To achieve clear skies, all industry had been shut down for a week to let the pollution dissipate. This was so the immense airforce flyover would be visible - something that had been embarrassingly impossible for the 40th anniversary.
In the pre-dawn light at the CCTV building the media lined up and were checked. Equipment was X-rayed and sometimes dismantled - presumably to ensure no one had guns or bombs.
Eventually, everyone was herded aboard a couple of buses and driven past multiple checkpoints into Tiananmen to be penned into a small area of terraced seating. The experienced correspondents had brought playing cards and flasks of coffee and sat in groups sharing memories and gossip.
The centre of town was empty. The metro had been shut down; all businesses were closed.
Tens of thousands of economic migrants without permits for abode had been rounded up and shipped away along with any possible troublemakers.
No one was permitted to look out windows along the parade route. Reportedly, 660,000 pensioners had been deputised to patrol the streets for weeks beforehand looking for trouble.
You might be starting to get the idea about what lengths can be gone to.
The parade itself was reported as having half a million participants, including hundreds of deafening battle tacks, mobile ICBMs and tens of thousands of soldiers chosen for their identical height and drilled so perfectly they looked like animation.
But there were only a few thousand spectators in the stands. The event was made for television, beamed out to the nation.
The journalists around me took notes and snapped shots but were incapable of actually reporting anything because the cellphone networks had all been switched off. Nothing was left to chance.
'A carefully judged slap'
So taking all that into account, consider how much careful planning occurs for a G20 meeting. It's a big thing and an opportunity for host prestige. No one wants to be overshadowed on their own turf.
When Barack Obama arrived in Hangzhou on Sunday on Air Force One - a plane that screams prestige and power - to find no red carpet stairway for the plane, with Mr Obama forced to exit from the lower belly door, the odds of that being an oversight are pretty low.
If it had been a security concern causing the diminished entrance, the president's national security advisor would surely have been too preoccupied to be arguing with local officials over the treatment of the press, who were being denied the traditional presidential arrival photos.
The intention was made even clearer when Chinese officials suddenly demanded to control how many Americans could enter the president's destination before him.
None of these elements of the stay would have been left for negotiation on the spot. They would all have been minutely arranged by the president's advance staff and Secret Service agents.
This was a carefully judged slap - a reminder of whose turf the Americans were on and who called the shots in China.
Such things are not unusual, but they are frequently overlooked.
Sometimes they are arranged to look like an innocent mistake, like master diplomatic chess player Vladimir Putin allowing his Alsatian dogs to be let into a meeting with Angela Merkel - a woman with a phobia of the breed after her youth in East Germany.
At a G20 meeting, however, the media have little else to discuss besides process stories. Consider that the media highlight of most G8 summits is the photo opportunity with leaders obliged to wear corny local attire - something that itself might sometimes have psychological intent.
Innocent mistake or return play?
Which brings us back to that tweet from the US Defence Intelligence Agency's official Twitter account, sent and then quickly deleted, that read, "Classy as always China."
An apology followed. It's easy to picture a PR intern running both their personal and an official account simultaneously and hitting send on the wrong one.
Earlier today, a tweet regarding a news article was mistakenly posted from this account & does not represent the views of DIA. We apologize.— DIA (@DefenseIntel) September 4, 2016
The cynical among us will accept that that is perfectly likely - but will wonder whether the mistaken tweet too was just another small chess move in this tit-for-tat; deniable, but causing a loss of face for the Chinese.
Like the original incident, the tweet is unlikely to be widely reported in China. The audience of these manoeuvres is seldom the general public; these are the backstage squabbles that take place before the curtain rises on uniformly smiling faces and handshakes.
However, they show that - despite the cordiality - there are deep disagreements between these nations, not least recently over China's territorial claims in the South China Sea.
* Phil Smith is a journalist who has wasted his adult life revelling in the entertaining minutiae of foreign politics.