Traders are shocked that a president who said he would place tariffs on countries with whom the U.S. has notable trade deficits has put tariffs on some of those countries. After Canada, Mexico and China, the European Union may be next.

Stocks face the prospect of a global trade war following a sweeping series of tariffs put in place by President Donald Trump.

Nasdaq: Wall Street's main indexes dropped at the open on Monday as fears of a full-blown trade war and its impact on the global economy jolted markets around the world after President Donald Trump levied steep tariffs on Mexico,