Golf is a great game for politicians. It can be played with friends as well as enemies, with rivals as well as allies.
It can be used for ice-breaking as well as negotiations.
It can be used as a signal of friendship.
For all these reasons it is good for photo opportunities.
The game in Hawaii between Barack Obama and John Key was a prime photo op for the New Zealand leader.
It's election year and this is probably the best photo John Key can get with a foreign leader.
For the president himself, it is insignificant, a friendly gesture to a small player.
That famous presidential selfie at Nelson Mandela's memorial ceremony, it will be remembered, included Danish Prime Minister Helle Thorning-Schmidt, another minor politician.
Mr Obama's tweeting press man couldn't even spell New Zealand correctly.
It also pays to remember that Mr Obama has had very friendly encounters with German Chancellor Angela Merkel.
That didn't stop his spies from listening in on her cellphone. Statesmen bug their friends and play golf with them too.
Mrs Merkel was furious, but she shouldn't have been surprised. Geopolitics is not a game of golf.
The friendly encounter in Hawaii - together with a presidential high-five for Max, Mr Key's son - follows New Zealand's official re-entry into the American alliance in October.
US Defence Secretary Leon Panetta announced that Washington had lifted a ban on visits by New Zealand warships to US defence bases.
Mr Panetta said the US would lift restrictions on military exercises and facilitate more talks with New Zealand even though the country maintained its long-held nuclear-free stance.
He said the US and New Zealand would work together despite lingering ''differences of opinion in some limited areas''.
This was an astonishing end to the standoff over nukes, which New Zealand began in 1985 by banning nuclear ship visits. It ended not with a bang but a euphemism.
Visiting US admirals in the 1980s said the nuclear ship ban prevented them doing their work of protecting the free world. Now the nuclear ban is ''a difference of opinion in a limited area''.
New Zealand is now an ally as well as a friend both in practice and theory, although former US secretary of state Condoleezza Rice used the ''ally'' word as long ago as 2008. But let's be realistic about this.
The thaw partly reflects the fact that the standoff was futile, because New Zealand refused to budge.
Above all the great motive for warming relations has been the rise of China. This has changed the world.
The United States is no longer the sole super-power, and it is keen to ''reorientate'' its foreign policy towards the Pacific.
This means trying to contain China by wooing US friends and allies.New Zealand has responded to this overture - and hence the game of golf in Hawaii.
But we should not get too chummy with the US. New Zealand needs China, too.
Small countries should keep a certain distance from both the elephants as they dance around the Pacific rim.
- The Dominion Post