President Donald Trump tried Thursday night to move the conversation away from his former lawyer implicating him in federal crimes by tweeting out a common talking point of white nationalists and neo-Nazis.

Late Wednesday night, Trump tweeted that he had directed Secretary of State Mike Pompeo to investigate “the South Africa land and farm seizures and expropriations and the large scale killing of farmers”:

I have asked Secretary of State @SecPompeo to closely study the South Africa land and farm seizures and expropriations and the large scale killing of farmers. “South African Government is now seizing land from white farmers.” @TuckerCarlson @FoxNews — Donald J. Trump (@realDonaldTrump) August 23, 2018

Trump is referring to a virulent, racist conspiracy theory that has been a pet cause of hardcore white nationalists, neo-Nazis, and the alt-right for several years. More recently, Fox News’s Tucker Carlson, one of the president’s favorite conservative cable news pundits, has taken up the cause.

The conspiracy theory is based on the very real — and very controversial — issue of post-apartheid land reform in South Africa. But the white nationalists who propagate it have taken what is a genuinely thorny issue and magnified it beyond all objective fact, twisting it into what they see as a nightmare cautionary tale of “white genocide.”

Here’s what’s going on — and why it’s so disturbing that Trump is now basing US foreign policy decisions on a fringe white nationalist conspiracy theory.

The long, fraught history of racist land policies in South Africa

For nearly 50 years, starting in the late 1940s, the black Africans who make up the majority of South Africa’s population were subjected to an official government policy of institutionalized political and economic discrimination and strict racial segregation by the white European minority who ruled the country under a system known as apartheid. (In practice, discrimination against black Africans had gone on for hundreds of years before it ever became official policy.)

Among many, many other infringements on their basic rights, black South Africans were legally barred from living on, operating businesses in, or owning land in vast swaths of the country that were set aside for whites only. By the time apartheid formally ended in 1994, nearly 90 percent of all land in the country was owned by whites — despite the fact that they made up just 10 percent of the population.

Land reform efforts aimed at remedying this situation began when apartheid ended. But after nearly 25 years, the huge disparity hasn’t gone away: A 2017 audit by the South African government found that whites still owned 72 percent of private farmland in South Africa.

In 2016, the country’s parliament passed a bill allowing for “the expropriation of property for a public purpose or in the public interest, subject to just and equitable compensation.” In other words, the government could legally force white landowners to give up their land in return for a fair price. The land would then be redistributed to black South Africans.

But that process, too, has been slow — and people are getting tired of waiting. Support for a small, far-left political party that advocates for nationalizing all land in South Africa has been growing.

So now, with elections looming next year, the ruling African National Congress (ANC) party has decided to take more drastic action: amending the constitution to make it legal for the government to seize land without providing compensation.

That move is being welcomed by many in the country, but not everyone is convinced it’s a good idea. Some, including investors, worry that it could trigger a catastrophic economic crisis like the one that occurred in neighboring Zimbabwe when it enacted similar reforms in 2000. There, rapid land seizures panicked investors, causing them to flee the market in droves. That led to massive hyperinflation and food shortages that effectively collapsed the country’s economy: Experts put the cost to Zimbabwe’s economy at around $20 billion.

But another group of people — including white nationalists, neo-Nazis, and members of the alt-right in Europe and the United States — see the South African land expropriation plan as much more than a potential economic misstep: to them, it’s a full-scale genocide against the country’s white minority.

How a small lobbying group convinced people around the world that a “white genocide” is happening in South Africa

AfriForum is a lobbying group based in South Africa that advocates for the rights and interests of a segment of the country’s white minority known as Afrikaners. Formed in 2006, one of its biggest lobbying efforts in recent years has been aimed at convincing the international community that there is a widespread campaign of race-based killings targeting white farmers in South Africa.

In addition to a huge digital media presence, its leaders travel around the world to meet with prominent politicians and other influential people and promote this horrifying story.

There’s just one problem: The story isn’t real. There is no evidence of a widespread campaign of violence and murder targeting white farmers in South Africa.

As journalist Lynsey Chutel with the news outlet Quartz Africa reported in detail in June, white farmers have historically been the victims of violent attacks in South Africa — though it’s not always clear whether an individual attack was motivated by racial animus or simply because white farmers are “Isolated and believed to be wealthy.”

However, “In some cases the attacks and murders have been so brutal that many believe there is an element of race-based vengeance for apartheid,” Chutel noted.

And there have been several high-profile murders of white farmers in recent years.

But Chutel and others who have looked closely at the data say that not only does the current data not show any clear evidence that a massive wave of violence against white farmers is underway, but that some of the data even suggests that attacks on white farmers in the country have actually declined.

“After a peak in 2001/2002, the number of farm attacks—rape, robbery and other forms of violent crime short of murder—has decreased to about half,” Chutel wrote. “Similarly, the number of murders on farms peaked in 1997/1998 at 153, but today that number is below 50.”

Moreover, Joe Walsh at the New Statesman found that murder rates in South Africa’s affluent, predominantly white suburbs are far lower than murder rates in the poor, predominantly black townships. “If there was any kind of genocide being carried out against white people in the country then the safest areas of the continent’s most dangerous city would not be predominately white,” Walsh wrote in May.

Yet, as we’ve all come to understand so well these days, the fact that something isn’t true doesn’t mean people won’t believe in it — or promote it if it suits their agenda.

Trump didn’t just look into these reports — he tweeted them out

AfriForum has been incredibly effective at spreading its propaganda, particularly online.

As the Guardian’s Jason Wilson has written, stories about the dastardly plot against white farmers (which, again, doesn’t actually exist) have shown up on alt-right, white nationalist, and neo-Nazi websites including AltRight.com (which is run by white nationalist Richard Spencer), VDare, American Renaissance, and Stormfront.

Lauren Southern with the European alt-right group Identity Evropa made a documentary about the subject. An alt-right podcast called White Rabbit Radio has an episode about it. So does American Renaissance’s Jared Taylor’s podcast. It’s also a hot topic on the pro-Trump Reddit forum r/TheDonald.

But the conspiracy theory quickly moved from the darker corners of the internet into the slightly-more-mainstream-but-still-pretty-seedy corners of the internet: As Wilson notes, Ann Coulter tweeted in June 2017 that the “only real refugees” are “White South African farmers facing genocide.” Breitbart has covered it extensively, as has the Russian government propaganda outlet RT. And, of course, so has Fox News’s Tucker Carlson.

Perhaps it was inevitable, then, that it would make its way to Trump sooner or later.

Except that Trump didn’t just see a segment on Tucker Carlson’s show and quietly call up one of his top foreign policy advisers or a senior intelligence official to ask what the deal was.

That would be understandable — after all, it’s unrealistic to expect any president, let alone a former reality TV show host and real estate mogul, to know everything there is to know about what’s going on in every country.

That’s why presidents have an entire intelligence agency that is solely dedicated to providing them with the absolute best intelligence possible on every foreign policy issue that could ever come up.

Instead, Trump immediately ordered his secretary of state — America’s top diplomat, who is responsible for carrying out US foreign policy around the globe and for running a massive government bureaucracy — to investigate the matter. And then he tweeted it out.

It’s hard to overstate how unprecedented that is: The president of the United States just directed the secretary of state to look into a racist conspiracy theory he saw on Fox News — a conspiracy theory that is a major talking point for white nationalists and neo-Nazis.

Whether or not it’s actually true is irrelevant.

Correction: A previous version of this article described South Africa’s white minority as “Afrikaners.” South Africa’s white minority is actually made up of a combination of both English- and Afrikaans-speaking individuals. The term “Afrikaners” refers only to those who speak Afrikaans. The article has been updated to reflect this.