What to know as President Donald Trump imposes steep new tariffs on imports from Canada, Mexico and China, prompting retaliation and countermeasures.

The president’s trade assault, which makes no distinction between ally and adversary, is an assertion of U.S. dominance with significant risks.

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.

Some of the purported concessions that led to a 30-day pause on the tariffs were things Canada and Mexico had already done before Trump’s threat, but it’s complicated.