I remember reading a Larry Bond novel ages ago. Vortex. It deals with an even-more-far-right coup that takes hold of South Africa in the late 1980s, and ends up with a Cuban invasion of the country via Namibia. From what I remember the South Africans used a tactical nuclear weapon against one of the Cuban columns, which resulted in the Cubans retaliating with nerve gas, which ironically ended up hurting Cuba politically more than the nuclear strike hurt the South Africans. It ends up with NATO invading the country.
Obviously that's not real life. The original post doesn't specifically mention the apartheid government; as mentioned in the thread my hunch is that their rocket technology was probably more dangerous than their nuclear technology, because it's politically much more acceptable to sell rocket engineering abroad, it's easier to build rocket plants than refine uranium, and Mossad can't assassinate every South African rocket scientist. Does modern-day Syria have rockets that can reach Turkey?
The Israelis won't assassinate the SA scientists they would be helping them. There was a rumour that the Israelis tested a boosted fission weapon with SA help unfortunately for them the low cloud cover shifted