It was a more of a silent proxy war. US and Israel didn’t out front support but they did. Israel even provided rifles that their military still uses. Want to say they assisted them with their nuclear program but I’m not 100% on that.
Israel assisted South Africa with their nuclear program, 100%.
I wouldn't even call the proxy war silent. The Soviets at the time had strong footholds in Mozambique and Angola. Zambia was flirting with socialist policies. Ditto for Zimbabwe that kicked all their cacs out. For the United States, the UK and others, Apartheid was a minor inconvenience compared to the more critical need of ensuring South Africa was supported as a base of the West against the evil Soviets threatening to infiltrate all of Africa. Reagan and Thatcher openly told us what it was: South Africa was a valued partner in the fight against Communism and their Apartheid regime would be supported.
It's no coincidence that the fall of Apartheid accelerated after the fall of the Berlin Wall.