OK, several US governments did indeed support Pinochet and the like. I don't want to advocate that, no way, but by doing this they were acting in accordance with the Truman Doctrine - which may have prevented a fair portion of the world from becoming a communist paradise for workers and farmers.
Let's face it, even though many on here, including myself, are very critical of the US and its foreign policy, we should at least acknowledge that back in the times of Pinochet, there was one central danger to freedom: communism. And the Soviet Union was certainly not unhappy with things getting easier for the spread of it when Allende came to power.
However, the American government could certainly have done different and a lot better when it tried to prevent communism from spreading - there are better ways than supporting military, read terrorist, regimes.
As for today's American government: it has yet to show its diplomatic skills. During the 2000 campaign, I remember hearing on CNN that this election would not be about foreign, but domestic issues. Also, they mentioned that people who were seeking a charismatic leader would rather vote Bush; but those who wanted a decent politician would rather opt for Gore. Bearing that in mind, the current polarisation and weak handling of international politics are not really a surprise.
Don't cry because it's over, smile because it happened.