On May 25, the world watched as a police officer pressed his knee into the neck of a black man on the ground. The death in police custody of George Floyd in Minneapolis was the trigger for protests that have swept across 140 US cities and 50 states, leading to several arrests and wreaking wide havoc.

Four police officers have been charged with murder.

To African-Americans, this tragic incident was harrowingly familiar. Its many racist antecedents loom as grim landmarks across the decades. Since 2013, the Black Lives Matter movement has become embedded in the mainstream of US politics. Race, politics and culture have become intertwined.

In the last fortnight, far-right protesters have increasingly clashed with self-proclaimed anti-fascists (Antifa). Viral video clips have shown strong-arm police tactics being used to curb protests which began as predominantly peaceful, but have included looting and violence.   

Anger at the death of Floyd has boiled over at a unique moment in US history, amid a virus pandemic that has killed over 100,000 people. It has been exacerbated by an economic collapse in which more than 40 million Americans have lost their jobs, hurting minority populations in the US most.

In the White House, President Donald Trump, having first called Floyd’s death “shocking”, then took to Twitter to threaten a military response against “thugs” in Minneapolis, quipping “when the looting starts, the shooting starts”.

After demonstrations spread close to the White House, the president threatened any protesters breaching barriers with “the most vicious dogs, and most ominous weapons I have ever seen”. Soldiers from the National Guard were mobilised in a dozen US states by State Governors, as well as in Washington, as a line of defence against looting and violence.

But president Trump went a step further. His threat to invoke the Insurrection Act of 1807 to use the regular Army to quell riots has raised the prospect of deploying troops to put down an insurrection against the federal government.

President Trump’s own Defence Secretary, Mark Esper, has openly criticised his threat to send in the military, pointing out that active duty forces “should only be used as a matter of last resort and only in the most urgent and dire of situations”.

The former defence secretary, General Jim Mattis, has supported him, denouncing the president for trying to divide Americans and saying the country was now witnessing the consequences of “three years without mature leadership”.

The events unfolding in America suggest that the attempt to reassert white supremacy is being indulged and condoned by the nation’s president. Mr Trump knows that a hard-line approach plays well with his core supporters and could prove decisive in next November’s election in the country.

Trump has not sought to do what is expected of a president: to calm and unify the nation. Nor has he promised to seek answers to the racism in America’s police forces. Rather than pouring oil on troubled waters, he has opted for petrol.

Many fear he will seek to make white supremacy his re-election rallying cry. If this happens a new generation of black nationalists could rise to meet him and his kind, with tragic consequences. 

How the convergence of those forces plays out could yet shape an election in which black votes and turnout hold the potential to sweep the president from power.

A long, difficult summer is only just beginning. Ultimately it is the president who must find the words to lower the temperature. But first he has to want to.