In retrospect, it was inevitable that he would go there. These worlds were destined to collide. There is a long and unfortunate history that binds together strands of white supremacist ideology in the US and SA. Jim Crow and apartheid did not merely co-exist in parallel but distant corners of the universe, but were propped up by a cross-pollination of brutalities and policies that were shared in real time. That sharing did not end with the demise of each repugnant system, but was instead pushed out to the periphery, beyond mainstream mores.
It was jarring, but somehow reconcilable, to see the apartheid-era South African flag stitched onto the clothing of the race terrorist who marched into an African-American church in Charleston, South Carolina, in 2015 and gunned down worshippers.
The ties that bind. That flag carries racist yearnings on both sides of the Atlantic for a bygone era of "greatness". These jagged chords sound throughout our politics, but have hummed from the margins. It's a supersonic blast when they find amplification from the most powerful officeholder in the world.
It's hard to know what is worse - watching the US president taking policy notes from rabid talking heads on Fox News, or seeing an unindicted co-conspirator attempting to divert our global gaze from his criminal cabal by seeking to legitimise a dangerous racial myth about another country.
On Thursday, Donald Trump pulled off this double - after apparently watching a report by a reckless media personality on the long, vexing and simmering question of land reform in SA. Trump took to Twitter, which has become the official all-intrusive platform of his presidency, to declare that "the South African government is now seizing land from white farmers", and urging the state department to study "the large-scale killings of farmers".
Problem No 1? There are of course no large-scale killings of white farmers in SA. (The US has a far greater gun violence crisis that is unaddressed by this president.)
Problem No 2? The South African government is not seizing land.
Problem No 3? The US president is immersing himself in a deliberately provocative "white genocide" lie that is the playground of right-wing extremists (and apparently, Australian home ministers). He is aligning himself with AfriForum, an extremist group that describes apartheid as a "so-called injustice", and which has employed the spectre of violence against critics of its shoddy statistics.
Trump has never been to Africa, and this is the first time he's mentioned the continent in the thousands of tweets that pour from the White House. He certainly hasn't been to SA, where I served as US ambassador under president Barack Obama until 2016. The president has yet to appoint a replacement to our most important economic and security partner in the region. Instead, he has made his views on emerging nations clear, with a contempt that seems to reveal an underlying racism.
My South African friends have hard-earned expertise with a president dogged by charges of corruption and mounting investigations, with limited capacity for policy but unlimited talent for divisive political sleight of hand. In the US, those of us who are rank amateurs in this business are learning on the job and discovering that the stakes are high and have alarming consequences.
Trump knows nothing of the effort to undo the poisonous legacy of apartheid that has left black South Africans owning just 4% of farms, despite making up 78% of the population (whites own 72%, despite making up just 9% of the population). He knows nothing of the deliberateness with which blacks have been dispossessed - with tools like the Glen Grey Act of 1894 penned by Cecil John Rhodes himself, which systematically limited the number of Africans who could live on and own land; and the infamous Natives Land Act of 1913, which secured white hegemony over natural resources and was coupled with state-backed bank loans for white "landowners".
Observing this brutal dislocation, Sol Plaatje described the forced nomadic existence of his people: "As a result of the passing of the Natives Land Act groups of natives are to be seen in the different Provinces seeking for new land. They have crossed over from the Free State into Natal, from Natal into the Transvaal, and from the Transvaal into British Bechuanaland." This scattering of black Africans consolidated white economic settlements and white political authority. Land is a central font of material, symbolic and spiritual wealth that black South Africans were savagely divested of.
According to the World Bank, "SA's historical, highly skewed distribution of land and productive assets is a source of inequality and social fragility".
It's in the midst of this "social fragility" that Trump has hurled his grenade. Yes, the South African government under President Cyril Ramaphosa is talking about accelerating land reform - but in a way that seeks to balance property ownership rights guaranteed by the constitution with the need for more equity to nurture a more broadly shared prosperity. The debate is complicated and not without considerable controversy. But the brilliant South Africans, of all races, I've been fortunate enough to partner with and learn from, are more than capable of taking up and resolving this issue with rigour and grace. And certainly without the intervention of a US president who dabbles in racist demagoguery, from Charlottesville to Pretoria.
In addition to serving my country in this remarkable republic, I now lead a foundation that's worked in SA for 25 years to support many of the civil society groups that make certain everyone's voice is heard in this land reform debate. We also support the broader effort to undo the deep structural damage left by apartheid, such as an education system that still leaves black pupils without desks and decent toilets, let alone computers and the best teachers.
In the past, the US embassy in SA has supported these efforts. We are blessed with outstanding foreign service officers in our embassy and consulates who can be counted on as caring partners with a humble integrity, despite the gyrations in Washington.
By blundering into an issue that remains of existential importance for SA's economy, and by lifting up the voices of racist extremists, Trump does great harm to the search for justice in SA. He also hurts US interests. But the true bonds between our people, tightened by our aspirational constitutions, will yet endure. With the flies increasingly buzzing around the White House rubbish pile, perhaps this tweet isn't really about SA at all.
• Gaspard, president of the Open Society Foundations, is a former US ambassador to SA...