Raya Salter remembers the yells as a child when she asked her mother to turn up the heat in the winter: “Put on a sweater. Put on two sweaters. Here’s an extra blanket. That’s gonna make it work because the heat is not going up.

But, at the same time, no option is off the table—including restrictions on energy and natural resources. Because of the highly-linked energy systems of the two countries, such a move could wreak significant havoc on the U.

Mark Carney, Canada’s incoming prime minister, is no stranger to crises. Now he faces what is arguably the challenge of a lifetime: President Trump. Matina Stevis-Gridneff, the Canada bureau chief for The New York Times,