(6) He's said he wants to "renegotiate NAFTA" and is opposed to the free trade agreement with Columbia. The affects of such a protectionist trade policy could be the similar to that of the Smoot-Hawley Tariff of 1930.
the biggest danger is actually trade action against China. They hold a lot of our debt (which Obama wants to expand) and if they get ticked off, they may retaliate against taiwan. And then it could get really ugly.