President Donald Trump late Thursday threatened a 35% tariff on goods imported from Canada, a dramatic escalation in an on-again, off-again trade war with America’s northern neighbor and one of its most important trading partners.

The threatened tariff was the latest in Trump’s on-and-off tax on imports from around the world. But among the three largest U.S. trading partners, Trump reached a framework for talks with China and still doesn’t have agreements with Canada or Mexico.