I think sanctions are a difficult tool to control. It depends on what you prohibit and how that affects the particular country concerned. If your sanctions are placing too much burden on the innocent people of the country, you have to think again about how they are implemented, and try to target them better against the ruling elite.

In the case of SA, I would say that the main effect of the sanctions was to raise the profile of the situation, and in the end it was the raised public profile that changed the situation.

Bagpuss