Plus: What's the future of foreign aid after President Donald Trump moves to shut down the U.S. Agency for International Development?

Uncertainty surrounds the trade war touched off by President Trump’s tariffs. But some of the basics are taking shape.

President Donald Trump made good on his promise to impose steep tariffs on America’s three largest trading partners — Canada, China and Mexico — citing a national emergency on the flow of fentanyl and undocumented immigrants into the United States.