It was effective in Syria last month, after a decade (really several decades) of effort and hundreds of billions of dollars. All you gotta do is infinitely fund and arm ~~terrorists~~ “moderate rebels” and Bob’s your uncle.

What has been effective is the strategy of "make life as hard as possible on Cubans so most Americans will look at Cuba and think communism doesn't work."

Yep, and people think it's silly that North Koreans hate the US that starved them through sanctions, committed genocide, and dropped more tons of bombs on it than the entire Pacific Front.