The country’s new prime minister, Mark Carney, has been called the “Trump whisperer,” and negotiations have been cordial and professional. But it’s been a wild ride.

President Donald Trump threatened a 35% tariff on some Canadian goods and raised the prospect of increasing levies on most other countries, ramping up his trade rhetoric in comments that weighed on stocks and boosted the US dollar.

Try as it might to appease President Donald Trump, Canada remains a prized target in his trade wars and subject to the whiplash of his changes of heart. But products complying with an existing accord,