President Donald Trump’s blanket 25% tariffs on Mexico and Canada took effect on Tuesday, an extraordinary action aimed at bringing America’s top trading partners to heel. But it threatens to weaken the North American economy,

President Donald Trump delivered on his threat to hit Canada and Mexico with sweeping import levies, imposing one of the largest increases in US tariffs since the 1930s in a dramatic escalation of a trade war that stands to upend ties with major economic partners.