China is not in the United States, thus it is abroad. US customs is very clear on that. If you started charging import taxes on chinese goods (which assumes that you do not at present, which I doubt) then the treasury would of course recieve more money, not less.
To import LCD monitors with equipment for recieving television broadcasts (ie LCD TV's) from China into the EU the customs duty is 14%, thus very few assembled TV's are imported from China. Instead Sony, Panasonic and every other TV manufacturer have set up assembly plants in Slovakia and Poland and similar where the duty-free components are assembled and you have one TV. Similar schemes would be one way for the US to earn back some of it's long lost manufacturing base, if they do not already exist.
I have not found a good resource for checking US customs duties, but according to Wikipedia the US and China do not have any free trade agreement, so there should be some duty levied.
To find out EU customs duties you can play with my national customs agency, who in their usual exceedingly friendly manner offer English descriptions as well. They give me plenty of pens every time they visit.
http://taric.tullverket.se/taric/bin/tagAvdelningar.cgi
English under "Spr?k:"