U.S. President Donald Trump said on Thursday the United States would impose a 35% tariff on imports from Canada next month and planned to impose blanket tariffs of 15% or 20% on most other trading partners.

In a letter released on his social media platform, Trump told Canadian Prime Minister Mark Carney the new rate would go into effect on Aug. 1 and would go up if Canada retaliated.

The 35% tariff is an increase from the current 25% rate that Trump had assigned to Canada and is a blow to Carney, who was seeking to agree to a trade pact with Washington.