The U.S. and Canada are sparring over trade policy. The fact that the two countries are close allies makes the fracas seem all the more nasty. Thankfully, the adversaries agreed to retreat to their respective corners for 30 days,

Trump knows the United States has more leverage over its neighbors than they do over his country. But exploiting that position of strength could cause a historic rupture.

Amid warnings of price increases, Canada moved quickly to retaliate, China said it had planned countermeasures and Mexico said it would soon unveil its response.