One important area of foreign trade policy that was not mentioned in the article is the use of trade policy to exact penalties on "bad" countries. Trade sanctions are used to put economic pressure on a country, but only work if it is a multilateral agreement.
These types of sanctions can also become tricky situations for multinational companies to navigate. For example, China's trade restrictions with Taiwan put Boeing in a very tough situation. Boeing is a federal military contractor, and when the U.S government decided that it would sell military vehicles to Taiwan, Boeing was forced to comply or risk losing its U.S. arms contract. On the other hand, China was threatening to cancel Boeing's very lucrative contract and kick them out of the country if the company went through with the sale of military aircraft to Taiwan. I am not sure how this resolved itself, but it must have been a headache for Boeing management.