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 president said the blanket 35% would be on top of tariffs on certain sectors. That’s higher than the previous 25% rate.

Trump’s move deepens a rift between two North American countries that have suffered a debilitating blow to their decades-old alliance.