CNN

 — 

President Donald Trump's blanket 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, including that of the United States, at a time of significant stress.

Trump also doubled the tariff on all Chinese imports to 20% from 10%. Those duties sit atop existing tariffs on hundreds of billions in Chinese goods.

This is a developing story and will be updated.