When Boris Johnson starts copying Donald Trump’s signature move – taking sides in a culture war by firing off a string of tweets – you know that America’s global domination remains so complete it can turn even one of the country’s most grotesque defects into a cultural export.

In fact, you knew that already because the last three weeks have demonstrated it. The videotaped killing of George Floyd by a Minneapolis police officer has triggered antiracist protests in every corner of the planet. People have taken to the streets in Paris and Berlin, Tel Aviv and Stockholm; Floyd’s face has been painted as a mural on a shattered wall in Idlib, Syria. “I can’t breathe” has become a universal slogan. Floyd once told a high school classmate, “I want to touch the world”. And he has.

Of course, the protests are not solely in solidarity with Floyd and black Americans. In each country, they have been rooted in the very specific experience of that country. But America was the spur to action. Bristolians had been campaigning for years against the statue of Edward Colston. But it took the killing of a man in faraway Minnesota to bring it down, and spark a national inquiry into who and what gets memorialised in stone and bronze – the debate that got Johnson’s Twitter finger twitching, and to which we shall return.

It’s a paradox. The world denounces the racism that remains the defining birth defect of the United States, pointing its collective finger at that country to shame it – and yet, by that very act of castigation, it confirms America’s power. The US is still the global arena, the place where issues that vex every nation are played out. It remains the reflecting glass in which so much of the world sees itself.

Racism offers a clear example. There is hate in every country, of course, but largely thanks to its colonisation of the global imagination through TV and movies, America’s horrors are endowed with a vivid, even epic quality that somehow renders them uniquely universal. A killing in Minneapolis can trigger a global reaction, in a way that one in Manchester never would. Gene Hackman never starred in a film called Brixton Burning.

The result is that an episode that should be damaging for America’s global influence, its soft power, somehow only adds to it. Just as capitalism can co-opt and profit from anticapitalism – with corporations now seizing on the slogan Black Lives Matter as a useful bit of ad copy – so the US can gain from its failure to address the racism that has disfigured it since the founding of the republic.

We shouldn’t be surprised. This is a country that can turn even its most dysfunctional excesses into commercial gold – witness Netflix’s Tiger King – and it has done so for decades. While Britain tried to hush up its atrocities overseas, even burning incriminating documents through the so-called Operation Legacy, Hollywood made a cottage industry of examining, for example, the Vietnam war, cementing its place in international pop culture. And so while British teenagers in the 1980s might know nothing of Britain’s brutal crushing of the Mau Mau insurgency in Kenya, they certainly did know that the average age of a US combat soldier in Vietnam was 19.

This dynamic works well for America, but it should have the rest of us on our guard. For the aftermath of Floyd’s death has revealed the risks of importing yet another trademark US product: namely, the culture war.

Take Johnson and those tweets. The language (and punctuation) may not have been Trumpian, but the form is pure Trump. Not a speech, not a TV interview, but a direct, unfiltered appeal via social media to his base, and on a topic calculated to polarise public opinion. Cannily, Johnson avoided the question of slaver statues, opting to speak instead in defence of the Whitehall memorial to Winston Churchill defaced by protesters last weekend. You don’t need a poll to tell you that the PM is likely to have a comfortable majority on his side for that one.

There is a lesson here for campaigners and activists, a lesson from America. The right loves a culture war, because such a battle changes the subject – almost always shifting from ground on which they would lose to ground on which they can win.

Let’s imagine the initial focus had remained instead on a demand to tackle discrimination in policing and criminal justice, expanding to include the higher death rates from Covid-19 among black Britons. Johnson and others in power would now be on the defensive, forced to promise action.

But once the focus shifted, they could exhale with relief. Not only is a debate about statues or faulty TV shows a handy distraction from the specific injustices at the heart of all this, it also splits the coalition, even the consensus, that had, remarkably, formed in revulsion at Floyd’s killing. Once statues of Gandhi and Mandela are also boarded up for their own protection, as they now are, it means precious unity has been lost.

Of course, the case against memorials to slavers is cast-iron and just. But widening the focus allows those in charge to stop talking about something hard for them, and shift to something much easier. US-style culture wars don’t just poison the air: even when progressives win, victory often comes at the expense of the structural change that might matter more. In America, celebrities have been coaxed to make the right noises on race for years – and all the while the Minneapolis police department was left untouched.

So let’s be wary of adopting one of the US’s most unappetising exports. Let’s borrow instead the slogan, and wisdom, of its civil rights movement of nearly 60 years ago – and keep eyes on the prize.

• Jonathan Freedland is a Guardian columnist