Jamieson Greer says the escalation was a "natural consequence" of Canada choosing "senseless retaliation" over a near-final trade deal.

Canada struck back at U.S. President Donald Trump on Tuesday with tariffs on about $20 billion worth of U.S. goods. The outcome could resonate far beyond Canada.

Canada struck back at Trump on Tuesday with tariffs on about $20 billion worth of U.S. goods.