hi OP. Just a note that this subreddit does not permit discussion of events/conditions within the last 20 years. So, if you're not ok with a revised timeframe of 1965-1995, do consider x-posting to r/AskSocialScience, r/history or a current affairs sub like r/politics.

The end of apartheid in South Africa (since it ended in 1994, this is within the moderated timeframe).

Source in the Department of State archives

By 1990, South Africa was under a global arms embargo (UN resolution 418) as well as trade embargoes from both the US and EEC. However, not being (by far) a specialist on the topic, I will not risk an opinion on the causality link between these sanctions and the end of apartheid.