Last night, seemingly out of nowhere, President Trump tweeted out that he was instructing the secretary of state to “closely study” the land redistribution process of South Africa. Citing his most trusted adviser, Fox News, he warned that the “South African Government is now seizing land from white farmers” and that there was “large scale killing of [white] farmers.”

The tweet repeated a white nationalist talking point that has been swiftly moving from the fringes to the mainstream of the American right. But what exactly is the land issue around which that talking point was built? And why have white nationalists seized on it?

South Africa is in the middle of a heated debate over the redistribution of farm land. More than 70 percent of the land is owned by the white minority population, which makes up less than 10 percent of the total population. Much of this land was taken from black landowners during the era of apartheid, the country’s system of legal segregation and discrimination. After apartheid’s formal end in 1994, a policy of “willing seller, willing buyer” was adopted to implement a market-driven program of land reform, which was meant to address the glaring dispossession of black rural and poor people from land.

To date, that policy has failed to even come close to its goals. As a result, an increasingly frustrated electorate has pushed politicians to institute further reforms. The government responded by more aggressively buying land for the purpose of redistribution. But this week it changed directions, setting out to seize lands without compensating the current owners. Whether South Africa’s current plan for land redistribution, including cases with no compensation, will work, no one knows.

But the idea that it could work — that black South Africans could once again control their own land — has generated immense fear among white supremacists on both sides of the Atlantic. That’s because land has long been a primary source of independence, especially for black people. After the Civil War, land ownership was essential to fundamental, and possibly lasting, change — which is precisely why it was repeatedly denied to freed people, who understood land ownership as key to emancipation.

Land created the possibility of shifting the balance of power in a way that would empower the black community and weaken the dominance of the white, formerly slave-owning elite. During Reconstruction, the vote and land made up the two most pressing concerns for freed people, and they knew it was the latter that would secure the former.

To keep black people disenfranchised, white Southerners created oppressive poll taxes. Poll taxes required voters to pay a fee, in cash, before they could cast their ballot.

For free black people, this was often impossible. Denied their own land, black people were forced into sharecropping, a system under which they rented lands, often from former slave owners, and were paid with a portion of the crop, not money. They were often forced to buy seed and tools from the landlord on credit, which placed most freed people in a state of constant and crippling debt. Money was a rarity, and even when it did come in, it was usually already claimed by this debt.

White Southerners understood the importance of land as well, seeing it as a source of independence for the newly emancipated. It was that independence that they feared, so much that they created lurid visions of life in a truly emancipated South, visions that are starkly similar to those offered up by people who warn about “white genocide” today.

Take Thomas Nast, the “father of the American Cartoon,” who took on the corrupt political machinery of New York in the 1860s and 1870s. In “Colored Rule in a Reconstruction State,” Nast produced one of the most infamous pieces of racism depicting what he, and many others, imagined black political power to look like.

Nast’s image portrayed whites as victims of an unruly, uneducated, selfish class of people who were not fit to hold the reins of government. It was barbarous. It was violent.

Scare tactics like this and violence perpetrated by white Southerners worked. Land reform never happened in the United States. Not coincidentally, it took black Southerners nearly a century of fighting to achieve the political and economic independence they were promised in the age of emancipation.

The lack of land reform reverberated throughout every facet of black life in America. In the 1960s, the Black Panther Party argued that the condition of black people in America had its roots not only in enslavement, but in the effective re-enslavement of freed people to the land that was denied them. They understood, as W.E.B. Du Bois observed, that “the slave went free; stood a brief moment in the sun; then moved back again toward slavery.” Without land reform, there was little independence. And white Southerners and Northerners alike understood this fact.

In 1960s America, land may have been a symbolic representation, but today in South Africa, it is as real as it was for black Americans in the aftermath of the Civil War. Land redistribution in South Africa represents yet another broken promise — one that, if fulfilled, holds out the possibility of empowering a black population that far outnumbers the land-controlling white one.

The black population in South Africa understands that to address the systemic inequalities created by apartheid, a systemic redistribution of wealth must be undertaken. Only then can the economic and political independence that should have followed apartheid’s end truly be achieved.

It is that promise — or threat — of black independence and inequality that has transformed the question of land reform into a talking point for white nationalists and, now, for the president of the United States. Trump’s tweet may seem to be a random foreign-policy decision. But in the history of American and global white supremacy, it is yet another marker of the white fear of black power.