The Guatemalan coup is also a famous example of blowback. Because Arbenz was a progressive left-leaning president, Guatemala attracted left-wing volunteers from all over Latin America who wanted to be a part of this thing, which looked like it could be a model for the rest of the hemisphere.

One of these young idealists was Che Guevarra. Before he became a revolutionary, he was a left-wing doctor with a desire to help the poor and disposessed with his medical skills.

After the coup, he (along with many other young Latin American leftists) concluded there was no way to elect a progressive government that meant anything, because if you did, the U.S. would take it down. Che concluded that the only way to set up a left-wing government in Latin America was to take it and hold it by force--and arm yourself well enough to discourage American intervention.

This is precisely what he did in Cuba and what he tried to do in Congo, Argentina and Bolivia. Likewise, armed leftist revolutionary movements popped up all over Latin America--many manned by the same idealists who had been so disillusioned by the brutal end of the Arbenz experiment. And these leftist armed insurrections were often used as the justification for military governments coming into power (Uruguay and Argentina, for instance) or for military governments turning up the repression levels (in Brazil).

The point is that had the U.S. encouraged democracy in Guatemala in 1954 instead of snuffing it out, the history of Latin America in the '60s, '70s and '80s might have been much more peaceful and democratic. Maybe. The Guatemalan coup was a tragedy for Guatemala and for an entire continent.