>>55
According to the free dictionary:
"Intended or serving to subvert, especially intended to overthrow or undermine an established government"
The libertarians are not trying to undermine or overthrow the U.S. government. They are trying to save it from a huge fiscal crisis and possible despotism resulting from a corruption of the principles this nation was founded upon - individualism, freedom, and the constitution/bill of rights.
Government should be small, wise, and frugal. This is all according to the ideals of this nation's creators. The libertarian party wishes to restore government to it's proper place, so the citizens of this nation can run their lives themselves, in freedom.
Bearing this in mind, I think it's safe to say they are one of the most fundamentally "american" parties there is.