Donald Trump tweeted this on August 22, 2018:
What's this all about? Trump's 2018 tweet was prompted by President Cyril Ramaphosa announcing his support for a constitutional amendment that, in some cases, would allow the government to expropriate unused land without compensation. Trump took up the cudgel again a couple of days ago, prompted by an expropriation act finally being passed last month.
The whole thing is super complicated and goes back decades. Land reform was a bedrock tenet of the ANC, but over the years voluntary transfers haven't worked. White people still own more than 70% of the land. So President Ramaphosa has been under a lot of pressure to do something.
In addition, South Africa has a very high crime rate and white farmers in rural areas are murdered all the time. As it happens, this murder rate has declined quite a bit, but it still amounts to about 70 per year—which seems like a lot but is lower than the daily murder rate throughout the whole country. Most of the farm killings are the result of robberies gone bad, and the overall murder rate in South Africa is about four times higher for blacks than whites. Still, this has been a hot button issue for a very long time, so when Trump says South Africa is “treating certain classes of people VERY BADLY," he's explicitly talking about white people.
Is white South African immigrant Elon Musk whispering in Trump's ear about this? I wouldn't be surprised, but he hardly needs to. Trump has been concerned for a long time about whether South Africa's white people are getting a fair shake.