"Spreading democracy" is propaganda, everyone knows that. 

It's the US Empire universal mission. All empires must have one. The US go around to overthrow bad dictators that are forcing their good people to behave bad or dumb, if not killing them.  That's the story. No one believes it and still it's the one that will always be told. Empires just can't help themselves. 

The real reasons are always gepolitical. The CIA/SIS move was in the context of Cold War. 

It did kind of backfire? Yes. People make mistakes all the time.