When a man hoping to be president of the United States can sum up his own country with a photograph of a monogrammed gun and the single-word caption “America”, it may be time for the rest of the world to worry.

Instead they are laughing. Since the Republican nomination hopeful (although not very hopeful) Jeb Bush tweeted a picture of his handgun he has been mocked around the world with images that comically replace that violent symbol with the gentler images that sum up less trigger-happy places – a cup of tea for the UK, a bike for the Netherlands, a curry for Bradford.

The joke’s a bit thin, because what is currently happening in US politics is only funny if you are an alien watching from a spaceship and the fate of the entire planet is just one big laugh to you. For what is Bush trying to achieve with this picture? He’s trying to appeal to the rage and irrationality that have made Donald Trump’s bombastical assault on the White House look increasingly plausible while Bush languishes, a conventional politician swamped by unconventional times.

The centre cannot hold, WB Yeats wrote nearly a century ago, and this photograph shows exactly how off centre things are getting. When Jeb Bush – brother of one warmongering president, son of another, and a governor who sanctioned 21 executions during his tenure in Florida – embodies the centre ground, you know things have got strange. Compared with the strongman politics, explicit bigotry and perversion that a Trump presidency threatens, mere conservatism would be sweet sanity.

But this photograph reveals that that is not on offer. America, says Bush’s Twitter account, is a gun with your name on it. The candidate has his name inscribed on his weapon – Gov Jeb Bush, it says on the barrel. This man is a gun. He’s primed and loaded. You think Trump talks tough? Well, talk is cheap. “Speak softly, and carry a big stick,” said Theodore Roosevelt. Bush has got this gun, see, and he knows how to use it.

Violence has directly entered the bloodstream of US politics, this picture tells us. The comments immediately appended to it confirmed this, with sick jokers speculating it was some kind of suicide note. Sarah Palin and Donald Trump don’t need to wave guns about to show they mean business. Everyone can see that they are scary.

When the scary ones – the really, really scary ones – start getting their claws into democracy, what do you do? Bush, clearly one of the “losers” Trump is always telling us about, has responded with this pathetic attempt to play the macho man too. Of course, it looks puny. Having your name on your gun and revealing this in a photograph makes you look like a bullied schoolboy desperately trying to resemble a bully.

It is also a horrible image of America for a politician to put out. America is the land of the gun, Bush proudly tells us. This may be the message read by the pro-gun voters he is presumably trying to impress, but to everyone else in the world it’s a portrait of the American nightmare. How did the world’s most confident nation come to see the globe – and itself – as so terrifying? America is so frightening to itself that people need guns to protect themselves from their neighbours. As for outsiders, you’d better keep your weapon to hand at all times. America, a fortress full of trigger-happy civil warriors.

And how it has haunted modern times. The guns, the deaths, the wars. Growing up, seeing it from the other side of the Atlantic, the US was a spectacle of extremes. Assassinated presidents and napalmed foreign villages. Ronald Reagan sabre-rattling. It seemed a bit sick, then I finally went there and loved the place. The US has given the world so much, from Jimi Hendrix to Jackson Pollock, not to mention those moon landings. Now it seems the sickness was always serious, the gun in the mind was being loaded and primed.

Can the world’s first truly democratic nation, and in so many ways the greatest, become something truly as ugly as its enemies accuse it of being? This picture reveals that mainstream American politicians are giving up. They have no weapons to fight a politics so irrational it is a threat to civilisation. So let’s all laugh at this photograph. While we can.