>> Should the US become an unfriendly power to the rest of the western world, it will find the demand for its currency plummeting, which I don't want to outline is a big issue.

For those who want to return the US to the haydays of manufacturing, the days of cheap steel and people working in mills, a rock-bottom dollar is a necessary first step. To sell widgets, the US dollar needs to be low. And to get workers into low-wage mill jobs the population needs to be hungry.