Le Monde has a neat scoop from Wikileaks: Brazil's foreign minister, Celso Amorim once tried to calm the Americans down and explain why Brasilia was not that worried about Hugo Chavez: "He barks but doesn't bite."
Then things almost get worse: in 2004, Brazil tried to get the US to support their sale of Super Tucano trainer/light fighter planes to Venezuela by promising to help the opposition!
Once more with Wikileaks, we learn less about substance than about form, but this one remains a keeper because it confirms that Itamaraty has a much better grip on what needs to be done with Chavez than the American government.
Why? Well, the US wanted to prevent Brazil from selling planes that had no bearing whatsoever on the strategic balance of South America (which is why Brazil was keen on selling them in the first place). Meanwhile, Chavez was getting 24 units of one of Russia's best fighter jets, which is a factor of instability. The more money Chavez invests in small turbo-prop trainer/ground support planes, the less is left for sophisticated weapons. Moreover, a rational policy would want Brazil as tightly involved as possible in Venezuela's military and weapons' technology programs.
Dumber still: Brazil needed US permission because the Super-Tucano uses American technology. By exploiting that fact to constrain Brasilia, the US was basically killing its chances of getting the contract for the major jet acquisition that Brazil has been toying with for years, and on which it should finally decide soon.
Both these details did not seem to register in D.C.
Michael Shifter is really right: the US is not conspiring any more in Latin America. Their policy doesn't seem to be going anywhere in fact: they are just blowing it, time after time.