Surprisingly, exports and imports, tariffs and quotas, and trade deficits and surpluses are central to American foreign relations. Ever since Franklin D. Roosevelt took office during the Great Depression, the United States has linked trade to its long-term diplomatic objectives and national...

It's hard to browse the news without seeing reports of yet another imposition of sanctions by one country on another. The United States has sanctions against more than 30 countries. Russia has repeatedly imposed sanctions against former Soviet republics. China has developed its own approach,...