A growing number of countries, including American allies, are striking trade deals as the Trump administration erects a higher fence around its global commerce.

President Donald Trump has once again thrust trade policy into the spotlight, threatening to impose sweeping 25% tariffs on goods from Mexico and Canada. This bold move comes as a shock to many, given the recent ratification of the United States-Mexico-Canada Agreement, which was meant to usher in a new era of North American economic cooperation.

The initial market reaction was relatively mild. Future reactions may not be.