I don't think this is true. If the CIA intervention in X had been a huge success, we would have heard all about it. If the CIA were involved in (say) removing

I don't think this is true. If the CIA intervention in X had been a huge success, we would have heard all about it. If the CIA were involved in (say) removing dictator X and that somehow led to democracy and peace how and why would they keep that secret when they don't and can't keep secret when the opposite occurs. Also, just looking at CIA actions we know about (removing democratic leaders for autocrats) it seems very unlikely the CIA has a super secret program doing the exact opposite. Do the two departments take turns or flip a coin to decide whether to give a job to the successful or counterproductive department?!