Still in Power
This is a clear case of the distinction between “intentions” and “consequences.” Most advocates of sanctions tell us about their intentions, but willfully ignore the consequences. They didn’t remove Saddam Hussein, but did impoverish the people of Iraq. They didn’t remove Fidel Castro, but did give his dictatorship a ready excuse for their failures (the Cuban state trades freely with the rest of the world — just not the US, but they don’t produce much that anyone else wants). They generally don’t work. (Economic sanctions strengthened apartheid in South Africa, but it seems that the sanctions on travel and sports helped to undermine the regime; if so, that is the only major exception of which I can think, and it was not the purely trade sanctions, but the travel and cultural sanctions that seemed to have done the job.)
More analysis (from studies published over a long period of time) here.