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.

Canada has been a key trading partner and ally of the US for decades. But along with Mexico, it now wears a bull’s eye for Trump in his second stint in the White House as he tries to reorder the global system of largely free trade by slapping tariffs on friends and foes alike to address what he calls unfair trading practices.

OTTAWA — Canada is delaying its plans to slap retaliatory tariffs on U.S. steel and aluminum after President Donald Trump sent a letter extending the deadline for trade negotiations between the two North American neighbors — though he also threatened to impose higher tariffs.